Setting the Scene

MOH/S/IMR/47.05 (JL)

Environmental Health Focus Managing the Environment for Health in the AsiaPacific

Volume 2, Number 2 2004

ISSN: 1675-3941

ACKNOWLEDGEMENTS We would like to record our thanks to Mr. James Arthur Ireland and Mrs. Robyn Longhurst for their invaluable advice and assistance in ensuring the succesful publication of this journal.

Environmental Health Focus Managing the Environment for Health in the AsiaPacific Volume 2, Number 2 2004

This EH Focus serves an Environmental Health Research Information Clearinghouse function. It aims to develop environmental management for health with the following purposes: • • • • •

To promote Environmental Health (EH) research and development within Malaysia and the AsiaPacific; To translate research outcomes to EH policy makers, EH practitioners, community leaders and researchers; To engage stakeholders locally, nationally and regionally in Environmental Health Action Planing (EHAP); To equip these stakeholders as environmental managers for health in Malaysia and the AsiaPacific; To render national, regional and community life sustainable.

A Joint Publication of the Environmental Health Research Centre, Institute for Medical Research, Malaysia. supported by Centre of Environmental Health Development WHO Collaborating Centre for Environmental Health, University of Western Sydney, Australia. About the cover Children - copyright ©Ben Chi, 2002 Batu Caves - copyright © www.tropicalisland.com Malaysia palms, Boat - courtesy of Project Trust Six banded Wrasse - copyright © Zafer Kizilkaya Kinabatangan river, Orangutan, Rhinoceros hornbill, Rafflesia, Dayak man copyright © Vladimir Dinets

Editorial Policy and Contacts Environmental Health Focus Managing the Environment for Health in the AsiaPacific Volume 2, Number 2, 2004 © Copyright Environmental Health Focus 2003 ISSN : 1675-3941 All editorial communications to:

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iv

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v

Contents In this Focus Setting the Scene 7

How EH Focus promotes interaction

Ne ws & V ie ws News iews 8

Strengthening Environmental Health in Malaysia – Linking Medical Geology to Health and the Environment

Fea tur e Ar tic les on future EH issues eatur ture ticles 11

Assessing Cancer Risks from Chemical Carcinogens

21

Medical Geology: An Emerging Discipline

Abstr acts Abstracts

vi

29

Ergosterol as an Indicator of Mould Growth on Building Materials

30

Can We Use Fixed Ambient Air Monitors to Estimate Population Long-term Exposure to Air Pollutants? The Case of Spatial Variability in the Genotox ER Study


News & Views Strengthening Environmental Health in Malaysia – Linking Medical Geology to Health and the Environment Joy Jacqueline Pereira, 2Stephen Ambu, 3Saim Suratman and 4Hamzah Mohamad

1

Introduction Medical Geology is a rapidly growing discipline that compliments environmental health in dealing with the impacts of geological materials and processes on humans, animals and plants (Finkelman et al., this volume). The discipline links geologists directly to medical, dental and veterinary specialists and indirectly to botanists and zoologists. Research on medical geology is integrative in nature, embracing disciplines as diverse as mineralogy and geochemistry to epidemiology and pathology. The focus is on relationships between human and animal health and rocks, soil and water. Medical Geology has the potential to help address a range of health problems including emerging diseases. The paper commences with an overview of international developments in the field of medical geology. This is followed by a brief description of the first workshop held in Malaysia to introduce medical geology. Salient points from the discussion on research and capacity building needs in Malaysia has also been documented. These include the types of research required, challenges related to data and potential collaborations and linkages to facilitate access to instruments and capacity building for research.

International Developments in Medical Geology The importance of geological factors on health, and the general lack of understanding the importance of geology in such relationships, led the Commission on Geological Sciences for Environmental Planning (COGEOENVIRONMENT) of the International Union of Geological Sciences (IUGS) to establish the International

Working Group on Medical Geology in 1996 (Selinus 2004). The Working Group was directed from the Geological Survey of Sweden (SGU), with the primary aim of increasing awareness of this issue among scientists, medical specialists, and the general public. In 2000 the United Nations Educational, Scientific and Cultural Organization (UNESCO) recognised the need for increased awareness and supported IGCP Project #454 on Medical Geology. The primary aim of the Project was to bring together, at the global scale, scientists working in this field in developing countries with their colleagues in other parts of the world stressing the importance of geoscientific factors that affect the health of humans and animals. In 2003-2004, the International Council of Scientific Unions (ICSU) also sponsored international short courses in this subject, in collaboration with SGU, United States Geological Survey (USGS) and the US Armed Forces of Pathology (AFIP). Through these initiatives, for the first time, leading scientists from developing countries came together in a truly international and inter-disciplinary way (involving geoscientists, physicians and veterinarians) to identify and tackle real problems of geoenvironment and health. Capacity building workshops and training courses have been held in over 60 countries world-wide (see http:// www.medicalgeology.org/ for further information). A book has been published by Oxford Press based on the proceedings of a Medical Geology Conference organised in Uppsala, Sweden in September 2000. In addition, national groups have been established to strengthen information dissemination and create synergies for research and policy advocacy in addressing issues related to medical geology. These significant achievements resulted in the International Working Group on Medical Geology being given Special Initiative status by the IUGS, operating directly under the

Senior Research Fellow/Associate Professor, Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia 2 Past Head, Environmental Health Research Centre, Institute for Medical Research Malaysia (IMR) 3 Senior Geologist, Minerals and Geoscience Department Malaysia 4 Professor, Geology Programme, Universiti Kebangsaan Malaysia 1

8


Strengthening EH in Malaysia

Executive. However, interest in Medical Geology is continuing to expand worldwide at an increasingly rapid rate and a formal structure is necessary to respond effectively to new opportunities, disseminate information efficiently to interested parties, and make critical decisions that will benefit the discipline. Thus, with support from the IUGS, a new association was developed in 2004, the International Medical Geology Association (IMGA). As part of its activities, the IMGA will play an important role in the establishment of the first Centre for Medical Geology in China. The second center is under discussion in South Africa.

Medical Geology in Malaysia Medical Geology was first introduced in Malaysia at the Workshop on Medical Geology: Metals, Health and the Environment, held at the Institute for Medical Research Malaysia (IMR) in Kuala Lumpur on 8th and 9th December 2003. The Workshop was convened by the Institute for Environment and Development (LESTARI) of Universiti Kebangsaan Malaysia, the Environmental Health Research Centre (EHRC), the Minerals and Geoscience Department Malaysia (JMG), and COGEOENVIRONMENT. It was jointly sponsored by the U.S. Armed Forces Institute of Pathology (AFIP), US Geological Survey (USGS), Geological Survey of Sweden (SGU), International Union of Geological Sciences (IUGS), International Medical Geology Association (IMGA), United Nations Educational, Scientific and Cultural Organization (UNESCO), International Geological Correlation Programme IGCP#454 and International Council of Scientific Unions (ICSU). About 40 professionals comprising practitioners and researchers from various government departments attended the Workshop. Among these were hydrogeologists, geochemists, chemists, soil scientists, biologists, environmental scientists, toxicologists, parasitologists, epidemiologist, public health engineers and other medical researchers. The Workshop was led by Directors of the newly established International Medical Geology Association, Dr. Olle Selinus of the SGU, Dr. Robert B. Finkelman of the USGS and Dr. Jose A. Centeno of the AFIP. The most recent information on the relationships between toxic metal ions, trace elements, and their impacts on environmental and public health issues were discussed. The scientific topics included environmental toxicology, environmental pathology, geochemistry, geoenvironmental epidemiology, extent, patterns and consequences of exposures to toxic metal ions in the general environment, biological risk assessment, modern trends in metal analysis and updates on the geology, toxicology and


pathology of metal ion and dust exposures. On completion of the Workshop, the participants obtained information on the types of evidence available about geological sources and processes and manifestations of exposures to toxic metal species. They also obtained an elementary understanding of environmental toxicology, epidemiology and medical geology as applied to the study of toxic metal species and trace elements.

Research and Capacity Building Needs for Malaysia The Workshop concluded with a Panel Discussion on the issues, needs and opportunities for medical geology and human health in Malaysia. The objective was to identify research needs as well as potential collaborations and linkages for this purpose. The Panelists were Dr. Stephen Ambu from IMR, Dr. Saim Suratman from JMG and Prof. Hamzah Mohamad from UKM. Each Panelist presented his viewpoint and this was followed by a lively enthusiastic discussion. Issues related to the extractive and food processing industries were highlighted (Hamzah 2003). In the case of the extractive industries, there is a need to investigate the geochemistry and toxicology of dust from rock quarries. In addition, the impact of gold mining, which is associated with high levels of arsenic and mercury, on the surrounding streams, soils and river life forms should also be investigated. In both cases, a clinical study of the surrounding population should be conducted. Building materials in the Klang Valley are derived from granitic rocks and sand, which contain minerals such as xenotime and monazite that are radioactive in nature. An investigation of the baseline and exposure levels of radioactivity in the population may also be in order. With respect to the food processing industry, the health impacts of using artificially fortified water and natural minerals in traditional food processing needs to be investigated. Preliminary results indicate high levels of heavy metals in products using such materials. The JMG collects and conducts chemical analyses of groundwater as part of their mandate. The groundwater data reveals high levels of arsenic, iron, calcium, copper and nitrate in some parts of the country. It was recommended that research be conducted to investigate the impact of such levels on the population, particularly where groundwater is the principal source of drinking water. The meeting was also informed of the drinking water database available at Engineering Services Division, Ministry of Health (MOH).

9

News & Views

Another aspect of interest was the geochemical database available at the JMG. Over the past decade, the JMG has accumulated much geochemical data as part of their mineral exploration activities. Such information, in particular the soil geochemistry, is very useful to determine areas with anomalous levels of heavy metals. Soil geochemical maps are very useful to identify problematic zones, so that research can be conducted to assess their implications, with respect to uptake through crops and cattle. The need to study the spatial distribution of diseases among the population in the effort to identify and isolate its principle cause was also highlighted. The dengue disease surveillance system developed by the Public Health Faculty of UKM Hospital, in conjunction with several collaborators, was cited as an example. One of the major challenges in Malaysia is difficulty in obtaining data in an appropriate format. Data is collected on a routine basis at national, state and local levels, sometimes as part of enforcement activities. This is particularly true for data on water quality and health related matters. Unfortunately, the collection of such data is not coordinated and there is no common approach to data management. The problem of poor documentation is compounded by routine transfer of officers in charge of such data. In addition, data collected by some institutions have to be bought, and this sometimes impedes research activities, particularly in universities. The discussion also focused on the availability of instruments and capacity building for research in medical geology. Participants were informed that the AFIP welcomes international collaborations and this could be one way to address problems related to non-availability of instruments. Access to training, instruments, internships and grants for research would also be available with the imminent establishment of a Centre for Medical Geology in China, with support from the US Government. The goal of the proposed Centre is to find practical solutions to a wide range of environmental health problems. In addition to training and technical support, the anticipated benefits of such a Centre would include developing experience with environmental health issues and establishing early warning systems for emerging diseases. The discussion ended with a call to establish a National Committee for medical geology in Malaysia. It was proposed that the proposed Committee oversee research needs and collaboration to strengthen capacity in this discipline in the country. The three local institutions that organised the Workshop were requested to take the lead in this matter.

10

The three institutions have since met and are planning follow-up activities.

Conclusions Research opportunities for medical geology are abundant in Malaysia given its importance to public health and well being. Such opportunities encompass issues related to the extractive and food processing industries, elevated levels of heavy metals in groundwater and soil, and its implications on the population, crop and cattle. Notwithstanding this, there are many challenges to be addressed, particularly with respect to data availability, resources and capacity. In this context, potential collaborations and linkages can be established to facilitate access and mobilise resources.

Acknowledgements The authors wish to thank the Directors and staff of the IMR, JMG and LESTARI for their support in the organisation of the workshop. The support of the Directors of the newly established International Medical Geology Association (IMGA) is also gratefully acknowledged.

References 1.

Finkelman, R.B., Centeno, J.A., Selinus, O. and Pereira, J.J. 2004. Medical Geology: An Emerging Discipline. Environmental Health Focus – Managing the Environment for Health in the Asia Pacific (this issue).

2.

Hamzah Mohamad 2003. Research Opportunities and Needs on Environmental Toxicology, Medical Geology and Human Health: Malaysian Perspective. Presentation at the Workshop on Medical Geology: Metals, Health and the Environment, Institute for Medical Research Malaysia, Kuala Lumpur. 8th and 9th December 2003.

3.

Selinus, O. 2004. IUGS Initiative on Medical Geology, 2000-2004. Report prepared for the Inaugural Meeting of the IUGS Commission on Geoscience for Environmental Management (GEM). Florence, Italy, 18-19 August 2004.

4.

Skinner, H.C.W. and Berger, A. R. (Eds.) 2003. Geology and Health – Closing the Gap. Oxford University Press, New York. 179 pp.


Feature Articles on future EH issues

Assessing Cancer Risks from Chemical Carcinogens Jamal Hisham Hashim and 2Zailina Hashim

1

Abstract The recent revelation that the cumulative lifetime cancer risk of 1 in 5.5 persons for Peninsular Malaysians invoked serious questions as to the risk factors involved for these cancers. Besides genetics, diet and behavior, the environment can also contribute towards the risk factors for cancers. However, the roles of the environment and the carcinogens that it harbors in contributing towards human cancers have not been clearly defined and assessed. There are two types of risk assessment. Qualitative risk assessment merely characterizes or compares the hazard of a chemical relative to others. Quantitative risk assessment is a methodological approach in which the toxicities of a chemical are identified, characterized, analyzed for dose-response relationships, and the data generated are applied to a mathematical model to produce a numeric estimate representing a guideline or decision concerning allowable exposure. Risk assessment comprises the four steps of hazard identification, exposure assessment, dose-response assessment and risk characterization. It acts as a bridge between scientific research and risk management. There are several uses for cancer risk assessment. Firstly, it may be used for setting exposure guideline for carcinogens in the environment. Secondly, cancer risk assessment can be used to assess the risk of cancer from exposure to potential pollutants from a proposed project or activity. Thirdly, cancer risk assessment is useful in protecting consumers against chemical carcinogens in the environment. It is obvious that we can no longer ignore the threat from chemical carcinogens. Since most scientists do not prescribe to a threshold dose for chemical carcinogens which would allow the setting of risk-free standards, risk assessment becomes a powerful tool for prescribing an

acceptable or tolerable risk pertaining to human exposure to chemical carcinogens.

Introduction The recent revelation that the cumulative lifetime risk of cancer is 18% or 1 in 5.5 persons for Peninsular Malaysians in the First Report of the National Cancer Registry has invoked serious questions as to the risk factors involved for these cancers (Lim et al., 2003). In the industrialized world, it is estimated that as high as 30 to 50 % of the population will develop some form of cancer during their lifetime (Hope and Fischman, 1997). Besides genetics, diet and behavior, the environment can also contribute towards the risk factors for cancers. Various authors have attributed 70 to 80 % of cases of human cancers to environmental causes (Fischman et al., 1990). However, the role of the environment and the carcinogens that it harbors in contributing towards human cancers has not been clearly defined and assessed. Therefore, the effort to control chemical carcinogens in the environment has been done mainly as a preventive measure to reduce human exposure to these chemicals, rather than as a concerted effort to minimize cancer risks from the exposure to acceptable levels. This is evident when we consider that most of our ambient environmental standards and guidelines are for protection against non-carcinogenic health effects. Cancer arises from a single abnormal cell which replicates itself through repeated divisions to form a large clone of tumor cells. The initial stage in the development of the abnormal cell appears to result from an alteration or mutation

Environmental Health Unit, Department of Community Health, Faculty of Medicine, Universiti Kebangsaan Malaysia, Malaysia. 2 Environmental and Occupational Health Unit, Department of Community Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Malaysia. 1


11

Feature Articles

in the genetic material, deoxyribonucleic acid (DNA). Mutation may occur spontaneously or it may be caused by exogenous factors such as exposure to chemical carcinogens or radiation. Whether a tumor will develop or not will depend on factors such the efficiency of the cell repair mechanism, the presence of endogenous or exogenous agents that foster or inhibit tumor development, and the effectiveness of the immune system (Hope and Fischman, 1997).

Definition of Risk Let us look at risk in greater detail. We defined risk earlier as the probability of exposure of individuals, populations, or ecosystems to toxic substances or to hazardous conditions. More specifically, risk is the probability that an adverse event will occur and the consequences of the adverse event (The Presidential/Congressional Commission on Risk Assessment and Management, 1997). An adverse event can be an accident, an injury, a disease or mortality due to a specific cause. Risk can be lowered by reducing one or more of the components of risk: the probability that hazardous conditions will exist or that toxic substances will be released into the environment; the probability of exposure of people or ecosystems to hazardous conditions or to toxic substances in the environment; and the severity of consequences, that is, the number of injuries or fatalities per event (Louvar and Louvar, 1998). Table 1 presents the risk of mortality for Malaysians due to various causes in 1998, based on statistics from the Department of Statistics, Malaysia. It shows that the highest risk of mortality is from cardiovascular disease, where almost 6 out of every 10,000 persons died from the cause. Noncommunicable diseases like cardiovascular disease and cancers pose a higher risk of mortality to Malaysians than communicable diseases like pneumonia and tuberculosis. The lifetime (70 years) risk level of one in a million or 10-6 is normally accepted universally as the acceptable risk level for mortality or fatal disease like cancer. This translates into an annual risk level of 1.4 x 10-8 or 1 to 2 persons in every 100 million population. This acceptable risk level is lower than the annual risk for all events listed in Table 1.

Acceptable Risk As events or activities in life are never risk-free, society must identify a level of risk they consider as acceptable or tolerable. Government agencies and the courts sometimes refer to this acceptable risk as reasonable risk. Acceptable risk is a societal acceptance of a level of risk, which those who are being

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Table 1: Individual risk of mortality in Malaysia due to various causes in 1998 1 Caus e of M ortality

Individual Ris k

Cardiovascular disease

5.7 x 10-4

Cancers

2.2 x 10-4

Motor vehicle accidents

1.7 x 10-4

Septicaemia

1.4 x 10-4

Pneumonia

8.7 x 10-5

Kidney disease

4.8 x 10-5

Chronic obstructive pulmonary disease

4 . 6 x 10 - 5

Liver disease

3 . 6 x 10 - 5

Diabetes mellitus

3.4 x 10-5

Tuberculosis

2 . 7 x 10 - 5

Drowning

2.5 x 10-5

Falls

2.0 x 10-5

Asthma

1.9 x 10-5

Suicide

1.3 x 10-5

DOE's tolerable risk limit for fatal accident among workers

1.0 x 10-5

Meningitis

9.6 x 10-6

Homicide

9.0 x 10-6

Fires & flames

7.1 x 10-6

Accidental poisoning

4.2 x 10-6

Accidents due to firearms & explosive

4.0 x 10-6

Dengue fever

2.1 x 10-6

Railways accidents

2.1 x 10-6

Electrocution

1.7 x 10-6

Natural disasters

1.7 x 10-6

Machinery accidents

1.3 x 10-6

Viral hepatitis

1.2 x 10-6

DOE's tolerable risk limit for fatal accident among public

1.0 x 10-6

Malaria

9.3 x 10-7

Cholera

9 . 3 x 10 - 7

Struck by falling objects

8.9 x 10-7

Gas poisoning in homes

9.3 x 10-8

Air transport accidents

9.3 x 10-8

Water transport accidents Lifetime acceptable risk level of 10

4 . 7 x 10 - 8 -6

1.4 x 10-8

Adapted from Department of Statistics, Malaysia 1999. Vit al St at ist ics Malaysia. Estimated mid- year population in 1998 was 21,466,031.

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Assessing cancer risks from chemical carcinogens

subjected to the risk, consider as tolerable or as something they can live with comfortably. Thus, acceptable risk may vary from society to society or from community to community. A consensus on acceptable risk should be reached by comparing costs, benefits and alternative risks, especially those that have previously been accepted as tolerable (Louvar and Louvar, 1998). Therefore, a community which tends to benefit from a particular project or activity in their neighborhood such as employment opportunity, will be willing to accept a higher level of risk from that project, as compared to a community which does not seem to benefit much. The one in a million or 10-6 acceptable risk level for a potentially fatal event such as cancer is a societal guideline rather than a norm. The Food and Drug Administration (FDA) in the United States was the first government agency to use risk assessment to make regulatory decisions. They first proposed a method for the regulation of carcinogenic drugs used in foodproducing animals in 1973 with an acceptable lifetime risk level of 10-8. Later, this acceptable risk level was revised to 10-6. The United States Environmental Protection Agency (USEPA) does not make any definitive stand on the

Table 2: Equivalent one in a million risk of mortality Caus e of M ortality

Quantity to re ach one in a millionris k le ve l

Motor vehicle accident 1

2 days

Falling

18 days

1

Drowning 1

15 days

Fire 1

51 days

Electrocution 1

215 days

Air Trip (radiation) 2

10 hours

Diet sodas (saccharin) 2

40 cans

Peanut butter (aflatoxin) 2

6 pounds

Smoking 2

2 cigarettes

Adapted from the Department of Statistics, Malaysia 1999. Vital Statistics Malaysia. Estimated mid- year population in 1998 was 2 1, 4 6 6 , 0 3 1. 2 Gratt, 1996.

1


acceptable risk level. However, with respect to cleanup of hazardous waste sites, the agency requires a cleanup that would bring the level of public risk to below 10-6 (Hallenbeck, 1993). Table 2 is a compilation of the length of time or the amount of a substance required to reach the one in a million risk of mortality in Malaysia.

Non-Threshold Dose Response for Cancer Risk With most toxic effects of chemicals, there are doses or exposures below which no adverse effect is observed. This is usually termed as the threshold dose which is normally classified as the ‘no observed adverse effect level’ (NOAEL) or the ‘lowest observed adverse effect level’ (LOAEL) in toxicological studies. The threshold dose normally relates to a non-carcinogenic health effect of a specific chemical, and it forms the basis for the promulgation of environmental standards and guidelines. There is a controversy on whether such a threshold dose exists for a chemical carcinogen. A non-threshold or zero threshold dose-response relationship is used to evaluate toxicants which are known or assumed to convey some risk of adverse response at any dose above zero. Non-threshold toxicants include genotoxic carcinogens and genotoxic developmental toxicants (Hallenbeck, 1993). Given the assumption that a single mutation of the DNA in a single cell can set the stage for tumor development, it is thus theoretically possible that a single molecule of a chemical carcinogen can lead to cancer. This means that any exposure to a chemical carcinogen dose, no matter how small, can translate into cancer. Thus, a threshold dose may not exist for a chemical carcinogen, which subsequently means that the risk of developing cancer following an exposure to a chemical carcinogen can never be zero. However, there are those who argue that the no threshold concept is illogical as the likelihood that a molecule will reach its target cell is lowered with small doses; the carcinogen may react with other cellular nucleophiles such as proteins; the liver may rapidly metabolize the carcinogen; and there is a functional DNA repair mechanism.

Risk Analysis and Assessment of Carcinogens Before we can discuss the issue of assessing cancer risk, we first have to define some risk-related terms. A hazard refers to the source of a risk. A carcinogen is a cancer hazard to human health, but it does not pose a cancer risk unless someone is exposed to it. Thus, risk is the probability of

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Feature Articles

exposure of individuals, populations, or ecosystems to toxic substances or to hazardous conditions (Louvar and Louvar, 1998). In this article, we are concerned with assessing cancer risks from chemical carcinogens, and this may be achieved through risk analysis. The objective of risk analysis is to provide a scientific framework to help decision makers and other concerned individuals make informed decisions that will ultimately solve or mitigate health and environmental problems (Cohrssen and Covello, 1989). Risk analysis comprises risk assessment, risk management and risk communication. Risk assessment is a methodological approach in which the toxicities of a chemical are identified, characterized, analyzed for dose-response relationships, and the data generated are applied to a mathematical model to produce a numeric estimate representing a guideline or decision concerning allowable exposure. Risk assessment comprises the four steps of hazard identification, exposure assessment, dose-response assessment and risk characterization (James, 1985). Risk assessment acts as a bridge between scientific research and risk management (Sexton, 1995). While scientists are more concerned with scientific research, policy makers are more interested in risk management (Figure 1). Unfortunately, scientists and policy makers are usually incommunicative because they do not seem to be speaking the same language. Journal publications and scientific reports are usually incomprehensible to policy makers, and they are unable to interpret the health risks associated with health hazards reported by scientists. Risk assessment can provide a common platform for both scientists and policy makers to deliberate on the same issue and to communicate the right information back and forth. In Malaysia, the authors believes that the introduction of risk assessment into the environmental health impact assessment (EHIA) exercise of the environmental impact assessment (EIA) procedure, has effectively facilitated this bridging process. Risk assessment provides one of the critical inputs into risk management which is a decision-making tool to help us control and manage health risks. Without risk assessment, the decision-making process in risk management will have minimal scientific inputs and will be based mainly on socioeconomic, political, legal and engineering considerations. Figure 2 is the authors’ proposal for a possible interface between risk assessment and risk management for both chemical carcinogens and non-carcinogens in our environment. As cancer risk assessment can now be carried out objectively and quantitatively, its poor representation in risk management will introduce unnecessary uncertainties

14

into the decision-making process.

Uses for Cancer Risk Assessment There are several circumstances where cancer risk assessment can be a useful tool. Firstly, it may be used for setting exposure guidelines for carcinogens in the environment. Figure 2 shows the flowchart for environmental health risk assessment and management for both carcinogens and noncarcinogens. As there is no threshold dose level for carcinogens, a threshold-based standard associated with zero risk cannot be established. Calculated cancer risk must therefore be compared to an acceptable risk level. Therefore, the allowable ambient exposure level for a carcinogen must be based on the acceptable cancer risk level it will pose to the exposed population. This allowable ambient exposure level can then be used to set an allowable emission or effluent standard for the carcinogen from a particular polluting source. What is still commonly practiced in many countries is the opposite of what is being suggested above. Normally, an emission or effluent standard is set based on the most appropriate or best available pollution control technology, and the resulting pollutant ambient level is then monitored and assessed for its ecological toxicity and human health outcomes. The problem with this pollutant control approach is that the emission or effluent standard may not be associated with an acceptable cancer risk level in the exposed population. For example, a highly stringent emission or effluent standard may not make much sense when the risk of cancer is negligible due to the absence of a human population downwind or downstream of the polluting source. Yet, most countries have a uniform emission and effluent standards as well as ambient guidelines to fit all environmental scenarios. Secondly, cancer risk assessment can be used to assess the risk of cancer from exposure to potential pollutants from a proposed project or activity. In Malaysia, this is being carried out through EHIA which is part of the EIA process. EHIA has managed to extrapolate the impacts on environmental components such as air and water to impacts on human health including cancer. Thirdly, cancer risk assessment is useful in protecting consumers against chemical carcinogens in the environment. For example, there have been concerns raised on possible cancer incidences from consumers’ exposures to benzene from the refueling of unleaded gasoline at the gas pumps and to formaldehyde from the off-gassing of office furniture and carpets. Probable cancer risks from such consumers’ exposure may be computed and assessed based on certain



Science Policy Judgments

Science Facts

Policy Values

RESEARCH NEEDS AND PRIORITIES

Risk Management Scientific Research • • • • • •

Epidemiology Clinical Studies Animal Toxicology Cell/tissue Experiments Computational Methods Monitoring/Surveillance

Risk Assessment Dose-Response Assessment

Research Needs

No action Economic issues

Risk Characterisation

Hazard Identification

Legal issues Social issues

Exposure Assessment

Political issues Engineering issues

D E C I S I O N S

Information programs Economic incentives Ambient standards Control Devices Emission limitations Ban

SCIENTIFIC INFORMATION AND UNDERSTANDING

Research • •

Develops factual basis Explicitly considers personal and societal values


Risk Assessment • •

Estimates magnitude, likelihood and uncertainty of risk Requires scientific judgments and policy choices

Risk Management • • •

Integrates risk assessment with other issues Determines acceptability of risk and appropriate responses Emphasises values in selection of policy options

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Feature Articles

Figure 2: Inerface between risk assessment and risk management 1. IDENTIFY ENVIRONMENTAL HAZARD

2. COLLECT TOXICOLOGICAL DATA ON HAZARD

YES YES

ARE THERE ANY DOSE-RESPONSE INFORMATION ON HAZARD?

NO

CAN NEW TOXICOLOGICAL DATA BE GENERATED?

NO

IS THERE A SUBSTITUTE CHEMICAL? NO

YES

3. BAN CHEMICAL

4. DETERMINE CONCENTRATION OF CHEMICAL IN ENVIRONMENTAL MEDIA

5. CALCULATE CHRONIC DAILY INTAKE (CDI) FROM AIR, FOOD,WATER, SOIL, ETC.

IS CHEMICAL A CARCINOGEN ?

7. FORMULATE & REGULATE ENVIRONMENTAL STANDARDS

NO

6. OBTAIN REFERENCE DOSE (RfD) & CALCULATE HAZARD INDEX (HI) FOR

YES YES 10. OBTAIN SLOPE FACTOR FOR CHEMICAL

IS HI ≥ 1 NO 8. CONTINUE TO MONITOR CHEMICAL

11. CALCULATE CANCER RISK FROM CDI & SF

IS CANCER RISK ACCEPTABLE?

9. CONTROL EMISSION & RELEASE OF CHEMICAL

NO

CANCER RISK IS NOT ACCEPTABLE

12. CONTROL EMISSION & RELEASE OF CHEMICAL

YES CANCER RISK IS ACCEPTABLE

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13. CONTINUE TO MONITOR CHEMICAL



assumptions. Subsequently, measures can be taken to protect consumers by minimizing these risks to acceptable levels.

Qualitative Risk Assessment There are two types of risk assessment. The first is qualitative risk assessment which merely characterizes or compares the hazard of a chemical relative to others. It defines the hazard in only qualitative terms such as a mutagen, a teratogen, or a carcinogen, which connotes certain risks or safety procedures, and as such may not necessarily require a numerical assessment of risk. It relies more on the hazard identification and exposure assessment steps, and risk characterization is merely subjective and qualitative.

Quantitative Risk Assessment Quantitative risk assessment is an attempt to introduce science into the regulatory policy on carcinogens. By the late 1970s, pressures to regulate carcinogens were high. Often the data upon which such regulation was based comes solely from animal carcinogenicity studies. To allow scientists to extrapolate from these high-dose animal data to the more likely low-dose human exposure scenarios, mathematical models were developed. These paved the way for the evolvement of the field of quantitative risk assessment into what it is today (Gots, 1993). As defined earlier, quantitative risk assessment is a methodological approach in which the toxicities of a chemical are identified, characterized, analyzed for dose-response relationships, and the data generated are applied to a mathematical model to produce a numeric estimate representing a guideline or decision concerning allowable exposure. Quantitative cancer risk assessment has since developed into a widely applied and effective methodology for objective decision making concerning the regulation of carcinogens in our environment. General guidelines on the conduct of environmental risk assessment has been outlined by the Department of Health and Ageing and enHealth Council (2002) of Australia. Gratt (1996) for example, provides an extensive account on the applications of quantitative cancer risk assessment in the regulation of toxic air pollutants.

Cancer Risk Assessment Procedure According to the National Academy of Sciences, there are 4 steps in the risk assessment process for both carcinogens and non-carcinogens (Figure 1). These are hazard


identification, dose-response assessment, exposure assessment and risk characterization. The hazard identification step, which is the first step in risk assessment, examines the capacity of an agent to cause adverse health effects in humans and other animals. It is a qualitative description based on the type and quality of the data; complementary information such as structure-activity analysis, genetic toxicity and pharmacokinetic; and the weight of evidence from these various sources (USEPA, 1995). Another approach which the authors would like to propose is the identification of the types of environmental agents or hazards which can be characterized as either biological, chemical or physical hazards; recognition of hazard sources or reservoirs; understanding the modes of hazard release from reservoir, transmission in the environment, and entry into the human host; describing the toxicity characteristics of hazards; and susceptibility of the host. These are illustrated by Figure 3 which shows the agent transmission pathway in environmental health, as suggested by the authors. In the context of cancer risk, the agent reservoir is pollutant sources such as thermal power plant or solid waste incinerator; the modes of release are industrial effluents and emissions; the modes of agent transmission are either direct contact or vehicle-transmitted; modes of entry are either through inhalation, ingestion or skin absorption; and the chronic health effect is cancer. Hazard identification for chemical carcinogens includes identifying specific forms of the chemicals which are carcinogenic. For example, chromium (VI) is carcinogenic while chromium (III) is not. The International Agency for Research on Cancer (IARC) evaluated 885 agents for their carcinogenicity to humans. These include chemicals, groups of chemicals, complex mixtures, occupational exposures, cultural habits, biological and physical agents. IARC classify these agents into 5 groups as Groups 1, 2A, 2B, 3 and 4. Of these, Groups 1, 2A and 2B which comprise 388 agents are generally recognized as human carcinogens. The second step in risk assessment is dose-response assessment. It extracts information from the dose-response relationship for a particular chemical. A dose-response relationship or curve describes the graphical relationship between increasing dose (in mg/kg.day) of a chemical and its corresponding increase in the incidence (in percent) of an adverse response in groups of test animals or exposed human individuals. On a logarithmic dose scale, this curve is for the most part linear. A chemical carcinogen can have both a noncarcinogenic as well as a carcinogenic dose-response

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Figure 3: Agent transmission pathway in environmental health

AGENT RESERVOIR * (EG. ANIMALS, HUMANS & POLLUTANT SOURCES) MODES OF RELEASE * (EG. INSECT BITES, FECES, INDUSTRIAL EFFLUENTS & EMISSIONS) AGENT * (BIOLOGICAL, CHEMICAL & PHYSICAL)

MODES OF AGENT TRANSMISSION

VECTORBORNE * (EG. MOSQUITOES, FLIES & FLEAS)

DIRECT CONTACT (EG. VENEREAL & SKIN DISEASES)

VEHICLE-TRANSMITTED * (EG. AIR, WATER, FOOD, SOIL & FOMITES)

MODE OF ENTRY (EG. INHALATION, INGESTION, SKIN ABSORPTION & INSECT BITES) INTRINSIC FACTORS (EG. AGE, SEX, ETHNICITY, GENETIC & IMMUNITY)

HEALTHY HUMAN HOST *

EXTRINSIC FACTORS * (EG. PERSONAL HYGIENE, HABIT, NUTRITION & OCCUPATION)

UNHEALTHY HUMAN HOST

ACUTE HEALTH EFFECTS (EG. COMMUNICABLE DISEASES)

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CHRONIC HEALTH EFFECTS (EG. NONCOMMUNICABLE DISEASES)



relationship. For example, a non-carcinogenic response for arsenic would be skin hyperpigmentation and keratosis, while a carcinogenic response would be skin cancer. Both these dose-response relationships for arsenic were generated from human data. The carcinogenic dose-response relationship for a chemical carcinogen describes the carcinogenic risk per unit of exposure dose. This carcinogenic risk of a chemical carcinogen is given by its cancer potency factor or slope factor (SF). The slope factor is the slope of the dose-response curve and its unit is in (mg/kg.day)-1. Thus, the steeper the slope, the larger is the slope factor, and the greater is the cancer potency of the chemical carcinogen. For example, chromium (VI) with an inhalation slope factor of 41 (mg/ kg.day)-1 is a more potent lung carcinogen than cadmium with an inhalation slope factor of 6.1 (mg/kg.day)-1. Chloroform, with an inhalation slope factor of 0.08 (mg/ kg.day)-1 is a more potent liver carcinogen through inhalation exposure than it is a kidney carcinogen through ingestion exposure with an oral slope factor of 0.006 (mg/kg.day)-1 (Louvar and Louvar, 1998). The third step in risk assessment is exposure assessment. Exposure is the condition of a chemical or physical agent in contact with an organism (Gratt, 1996). Exposure assessment estimates the dose or the quantity of the risk agent or hazard received by individuals or the environment (Louvar and Louvar, 1998). It is important to realize that without exposure to or contact with the chemical carcinogen, there is no cancer risk. Therefore, the risk of acquiring cancer is dependant upon the potency of the carcinogen as described by its slope factor, and the dose of exposure to the carcinogen. Exposure dose to a chemical carcinogen is usually assessed over a lifetime. Chronic daily intake (CDI) or lifetime average daily dose (LADD) is the average daily intake of a toxicant by the human body that is averaged over a lifetime exposure duration of 70 years. CDI can be calculated using mathematical modeling based on parameters such as concentration of the carcinogen in the environmental media (air, water, soil or food), daily body intake rate (eg. 20 m3 per day for air and 2 L per day for water), frequency of exposure (eg. 365 days per year for inhalation exposure), duration of exposure (70 years for lifetime exposure), body weight (70 kg for an average adult male), and averaging time (70 years for chronic or carcinogenic effect). The unit for CDI is in mg/kg.day. Risk characterization is the final step in risk assessment. It is actually a summary of the first three steps of risk assessment. For cancer risk assessment, risk characterization is achieved


by multiplying the CDI with the slope factor. As the unit for CDI is in mg/kg.day and that for the slope factor is in (mg/ kg.day)-1, the two units will cancel out. The risk outcome is then expressed as a probability that is unitless. As discussed earlier, the universally proposed lifetime acceptable cancer risk level for the general public is taken as 10-6.

Conclusion It is still uncertain, to what extent chemical carcinogens presently contribute to the incidence of cancers in humans. It is even more uncertain as to the role they may have in the occurrence of human cancers in the future. Whatever their role may be, it is obvious that we can no longer ignore the threat from chemical carcinogens in our environment. As the cost of cancer treatment and management is becoming more and more inhibitive even in the developed countries, it seems irresponsible for society not to make an earnest attempt to prevent or at least limit the proliferation of the disease. Since most scientists do not prescribe to a threshold dose for chemical carcinogens which would allow the setting of risk-free standards, risk assessment becomes a powerful tool for prescribing an acceptable or tolerable risk pertaining to human exposure to chemical carcinogens. However, risk assessment is an evolving applied science that requires the integration of knowledge and skills from various disciplines like chemistry, mathematics, physics, physiology, toxicology, medicine, engineering, ecology and hydrology. This remains the greatest challenge to risk assessors across the globe.

References 1.

Cohrssen , J.J. and Covello, V.T. (1989). Risk Analysis : A Guide to Principles and Methods for Analyzing Health and Environmental Risks. The National Technical Information Service, Springfield.

2.

Department of Health and Ageing and enHealth Council. 2002. Environmental health Risk Assessment : Guidelines for Assessing Human Health Risks from Environmental Hazards. Commenwealth of Australia, Canberra.

3.

Department of Statistics, Malaysia. 1999. Vital Statistics Malaysia 1999.

4.

Fischman, M.L., Cadman, E.C. and Desmond, S. (1990). In: J. LaDou (Ed.). Occupational Medicine. Appleton and Lange, Norwalk, Connecticut.

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5.

Gots, R.E. (1993). Toxic Risk : Science, Regulation, and Perception. Lewis Publishers, Boca Raton.

6.

Gratt, L.B. (1996). Air Toxic Risk Assessment and Management : Public Health Risk from Normal Operations. Van Nostrand Reinhold, New York.

7.

Hallenbeck, W.H. (1993). Quantitative Risk Assessment for Environmental and Occupational Health. Lewis Publishers, Boca Raton.

8.

Hope, S.R., Fischman, M.L. (1997). Occupational cancer. In: J. LaDou (Ed.). Occupational and Environmental Medicine. Appleton and Lange, Stamford, Connecticut.

9.

IARC (International Agency for Research on Cancer). List of IARC evaluations. http:// monograph.iarc.fr/monoeval/grlist.html (accessed on 10 September 2003).

10.

James, R.C. (1985). Risk Assessment. In William, P.L. and Burson, J.L. Industrial Toxicology. Van Nostrand Reinhold, New York.

11.

Lim, G.C.C., Yahaya, H. and Lim, T.O. (Eds.) 2003. The First Report of the National Cancer Registry. National Cancer Registry, Malaysia, Kuala Lumpur.

12.

Louvar, J.F. and Louvar B.D. (1998). Health and Environmental Risk Analysis : Fundamentals with Applications. Prentice Hall, Upper Saddle River.

13.

Sexton, K. (1995). Science and policy in regulatory decision making : Getting the facts right about hazardous air pollutants. Environmental Health Perspective, 103, Suppl. 6 : 213-221.

14.

The Presidential/Congressional Commission on Risk Assessment and Risk Management. 1997. Framework for Environmental Health Risk Management, Final Report, Volume 1.

15.

USEPA. (1995). Guidance for Risk Characterization. US Environmental Protection Agency Science Policy Council, Washington.

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Medical Geology: An Emerging Discipline Robert B. Finkelman1, Jose A. Centeno2, Olle Selinus3, Joy Jacqueline Pereira4

Introduction Emerging diseases can present the medical community with many difficult problems. However, emerging disciplines may offer the medical community new opportunities to address a range of health problems including emerging diseases. One such emerging discipline is Medical Geology. Medical Geology is a rapidly growing discipline that has the potential of helping the medical community in the Asia Pacific Region and elsewhere to pursue a wide range of environmental health issues. In this article we provide an overview of some of the health problems being addressed by practitioners of this emerging discipline.

Background Silverman (1997) defined environmental health as the impact of environmental degradation on human populations. Medical Geology can be considered as a compliment of environmental health dealing with the impacts of geologic materials and processes (that is, the natural environment) on animal and human health. Medical Geology attempts to bring together geoscientists and medical/public health researchers to address health problems caused by or exacerbated by geologic materials such as trace elements, rocks, minerals, water, and geologic processes such as volcanic eruptions, earthquakes and dust. Medical geology is not strictly an emerging discipline but rather a re-emerging discipline. The relationship between geologic materials such as rocks and minerals and human health has been known for centuries. Ancient Chinese, Egyptian, Islamic, and Greek texts describe the many therapeutic applications of various rocks and minerals and many health problems that they may cause. More than 2,000

years ago Chinese texts describe 46 different minerals that were used for medicinal purposes. Arsenic minerals for example, orphiment (As2S2) and realgar (As2S3), were extensively featured in the materia medica of ancient cultures. Health effects associated with the use of these minerals were described by Hippocrates (460-377B.C.) as "… as corrosive, burning of the skin, with severe pain…" There have been many pioneering collaborations on environmental health issues between geoscientists and medical scientists (Bencko and Vostal, 1999; Cronin and Sharp, 2002; Centeno et al., 2002), but these studies have largely been driven by the interests and enthusiasm of individual scientists. What is different and exciting is that Medical Geology is now receiving institutional support from many organizations in many countries. Practitioners of Medical Geology have five principal responsibilities.

•

To identify geochemical anomalies in soils, sediments, and water that may impact on health.

•

To identify the environmental causes of known health problems and, in collaboration with biomedical/public health researchers, seek solutions to prevent or minimize these problems.

•

To evaluate the beneficial health affects of geologic materials and process.

•

To reassure the public when there are unwarranted environmental health concerns deriving from geologic materials or processes.

•

To forge links between developed and developing countries to find solutions for environmental health problems.

US Geological Survey, Reston, VA, USA US Armed Forces Institute of Pathology, Washington, DC 20306-6000 USA 3 Geological Survey of Sweden, Uppsala, Sweden 4 Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, Malaysia 1 2


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Among the environmental health problems that geologists are working with the medical community to address are: exposure to toxic levels of trace essential and non-essential elements such as arsenic and mercury; trace element deficiencies; exposure to natural dusts and to radioactivity; naturally occurring organic compounds in drinking water; volcanic emissions, etc. Geoscientists have also developed an array of tools and databases that can be used by the environmental health community to address vectorborne diseases, to model pollution dispersion in surface and ground water, and can be applied to some aspects of industrial pollution and occupational health problems.

Trace Element Exposure: Deficiency and Toxicity Trace elements play essential roles in the normal metabolism and physiological functions of animals and humans. Of these, some 22 elements are known or suspected to be "essential" for humans and other animals. Some are required in fairly large amounts (e.g., grams per kilogram of diet), and are therefore referred to as "macronutrients"; others are required in much smaller amounts (e.g., microgram-to-milligrams per kilogram of diet and are referred as "micronutrients". Sixteen elements are established as being essential for good health. Some (calcium, phosphorus, magnesium, and fluoride) are

required for structural functions in bone and membranes; some (sodium, potassium, and chloride) are required for the maintenance of water and electrolyte balance in cells; some (zinc, copper, selenium, manganese, and molybdenum) are essential constituents of enzymes or serve as carriers (iron) for ligands essential in metabolism; and some serve as essential components of a hormone (iodine) or hormonelike factor (chromium). Because these are all critical life functions, the tissue levels of many "nutritionally essential elements" tend to be regulated within certain ranges, which are highly dependent on several physiological processes, chiefly by homeostatic control of enteric absorption, tissue storage and/or excretion. Changes in these physiological processes may exacerbate the effects of short-term dietary deficiencies or excesses of trace elements. The sources of trace elements are varied. Food derived from soils is a major, significant route; however, other sources such as the deliberate eating of soil (geophagia) and water supplies may also contribute to dietary intake of trace elements. Diseases due to trace element deficiencies as well as excesses have been described for example, for iodine, copper, zinc, selenium, molybdenum, manganese, iron, calcium, arsenic, and cadmium. Endemic distributions of diseases directly related to the geographic patterns of soil deficiencies in selenium and iodine have been described in at least two general cases, the juvenile cardiomyopathy "Keshan

Figure 1: Photos demonstrating cases with severe muscular abnormalities associated with selenium deficiency in China (Kashin-Beck disease). These photographs were taken by Prof. Dr. Wang Zhilun (China) a leading researcher on selenium deficiency disorders.

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Medical ecology

Disease"and the iodine deficiency diseases goiter and myxedematous cretinism, respectively. In the following paragraphs, examples of adversed health effects due to trace element deficiencies and excesses will be described. Environmental chronic exposure to non-essential elements such as arsenic will also be described. Diseases due to Trace Element Deficiences: The connection between geologic materials and trace element deficiency can clearly be shown for iodine. Iodine Deficiency Disorders (IDD) include goiter (enlargement of the thyroid gland), cretinism (mental retardation with physical deformities), reduced IQ, miscarriages, and birth defects. In ancient China, Greece and Egypt as well as among the Incas, people affected by goiter, were given sea weed to provide the needed iodine. Goiter is still a serious disease in many parts of the world. China alone has 425 million people (40 % of the world's population) at risk of IDD. In all, more than a billion people, mostly living in the developing countries, are at risk of IDD. In all the places where the risk of IDD is high, the content of iodine in drinking water is very low because of low concentrations of iodine in bedrock. Selenium is an essential trace element having antioxidant protective functions as well as redox and thyroid hormone regulation properties. However, selenium deficiency (due to soils low in selenium), has been shown to cause severe physiological impairment and organ damage such as a juvenile cardiomyopathy (Keshan disease) and muscular abnormalities in adults (Kaschin-Beck disease) (see Figure 1). In the 1960s scientists suspected that the disease was of geological origin

and in the 1970s the probable solution was found. The disease was always located in areas with low selenium soils. The use of selenium in prevention and treatment of the disease was a great success. Toxicity of Essential and Non-essential Elements. Toxicity effects from exposure to excess amount of trace elements have been also described as due, in part, to natural geological sources. One of the most studied trace elements in this regard has been fluorine. Fluoride (F-), the ionic form of fluorine, can stimulate bone formation and it also has been demonstrated to reduce dental caries at doses of at least 0.7 mg/L in drinking water. However, excess fluoride exposure can cause fluorosis of the enamel (mottling of the teeth) and bone (skeletal fluorosis). Health effects from chronic exposure to non essential metals and metalloids such as arsenic have been also described as an area of research on Medical Geology. Arsenic and arsenic containing compounds are human carcinogens (IARC, 1987). Exposure to arsenic may occur through several anthropogenic sources, including mining, pesticide, pharmaceutical, glass and microelectronics, but the most prevalent sources of exposure today has been by natural sources. Exposure to arsenic occurs via the oral route (ingestion), inhalation, dermal contact and the parenteral route to some extent. Drinking water contamination by arsenic remains a major public health problem. Acute and chronic arsenic exposure via drinking water has been reported in many countries of the world, where a large proportion of drinking water is contaminated with high concentrations of

Figure 2: Photos showing arsenic-induced lesions of the skin. From left to right: Keratoric (ulceration) lesions of the foot, leg and hands. Photos: JA Centeno.


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arsenic. General health effects that are associated with arsenic exposure include cardiovascular and peripheral vascular disease, developmental anomalies, neurologic and neurobehavioural disorders, diabetes, hearing loss, portal fibrosis, hematologic disorders (anemia, leukopenia and eosinophilia) and multiple cancers: significantly higher standardized mortality rates and cumulative mortality rates for cancers of the skin, lung, liver, urinary bladder, kidney, and colon in many areas of arsenic pollution (Centeno et al., 2002; Centeno et al., 2002; Tchounwou, 2003) (Figure 2). Global Implications and Medical Geology Examples of Chronic Arsenic and Fluorine Poisoning. In Bangladesh, India, China, Taiwan, Vietnam, Mexico, and elsewhere, high levels of arsenic in drinking water have caused serious health problems for many millions of people (Kinniburgh and Smedley, 2001). Geoscientists from several countries are working with public health officials to seek solutions to these problems. By studying the geological and hydrological environment, geoscientists are trying to determine the source rocks from which the arsenic is being leached into the ground water. They are also trying to determine the conditions under which the arsenic is being mobilized. For example, is the arsenic being desorbed and dissolved from iron oxide minerals by anerobic oxygendeficient) groundwater or is the arsenic derived from the dissolution of arsenic-bearing sulfide minerals such as pyrite by oxygenated waters? The answers to these questions will allow the public health communities around the world identify aquifers with similar characteristics and more accurately determine which populations may be at risk from arsenic exposure. In China, geoscientists are working with the medical community to seek solutions to arsenic and fluorine poisoning caused by residential burning of mineralized coal and briquettes. Chronic arsenic poisoning affects least 3,000 people in Guizhou Province, P.R. China. Those affected exhibit typical symptoms of arsenic poisoning including hyperpigmentation (flushed appearance, freckles), hyperkeratosis (scaly lesions on the skin, generally concentrated on the hands and feet; Fig. 2), Bowen's disease (dark, horny, precancerous lesions of the skin. Chili peppers dried over open coal-burning stoves may be a principal vector for the arsenic poisoning. Fresh chili peppers have less than one part-per-million (ppm) arsenic. In contrast, chili peppers dried over high-arsenic coal fires can have more than 500 ppm arsenic. Significant amounts of arsenic may also come from other tainted foods, ingestion of dust (samples of kitchen dust contained as much as 3,000 ppm arsenic), and from inhalation of indoor air polluted by arsenic derived from coal combustion. The arsenic content of drinking water samples

24

does not appear to be an important factor. Detailed chemical and mineralogical characterization of the arsenic-bearing coal samples from this region (Belkin and coworkers, 1997) indicate arsenic concentrations as high as 35,000 ppm! Typically coals have less than 20 ppm arsenic and coals from Malaysia have less that 5 ppm arsenic (USGS unpublished data). Although there were a wide variety of As-bearing mineral phases in the coal samples, much of the arsenic was bound to the organic component of the coal. This observation was important for two reasons. Firstly, because the arsenic was in the organic matrix, traditional methods of reducing arsenic, such as physical removal of heavy minerals, primarily as-bearing pyrite, would not be effective. Secondly, because the visually observable pyrite in the coal was not a reliable indicator of the arsenic content, the villagers had no way of predicting the arsenic content of the coals that they mined or purchased. To overcome these problems a field test kit for arsenic was developed (Belkin et al., 2003). This kit gives the villagers the opportunity to analyze the coal in the field and identify the dangerous higharsenic samples as well as the safer low-arsenic coals. The health problems caused by fluorine volatilized during domestic coal use are far more extensive than those caused by arsenic. More than 10 million people in Guizhou Province and surrounding areas suffer from various forms of fluorosis. Typical symptoms of fluorosis include mottling of tooth enamel (dental fluorosis) and various forms of skeletal fluorosis including osteosclerosis, limited movement of the joints, and outward manifestations such as knock-knees, bow legs, and spinal curvature. Fluorosis combined with nutritional deficiencies in children can result in severe bone deformation. The etiology of fluorosis is similar to that of arseniasis in that the disease is derived from foods dried over coal-burning stoves. Adsorption of fluorine by corn dried over unvented ovens burning high (>200 ppm) fluorine coal is the probable cause of the extensive dental and skeletal fluorosis in southwest China. The problem is compounded by the use of clay as a binder for making briquettes. The clay used is a high-fluorine (mean value of 903 ppm) residue formed by intense leaching of a limestone substrate. Geophagia is also of concern in medical geology. Geophagy or geophagia can be defined as the deliberate ingestion of soil, a practice that is common among members of the animal kingdom, including certain human populations. Soil may be eaten from the ground but in many situations there is a cultural preference for soil from special sources such as termite


Medical ecology

mounds. Geophagia is considered by many nutritionists to be either a learned habitual response in which clays and soil minerals are specifically ingested to reduce the toxicity of various dietary components or as an in-built response to nutritional deficiencies resulting from a poor diet. Geophagy is attaining renewed and serious interest within the scientific research community. One particularly interesting case of high element exposure is "sickness country" in Australia. This area in the Kakadu region of the Australian Outback has been known by the aborigines as an area that will cause sickness. Hence the area is regarded by the aborigines as taboo and should not be entered. Geochemical researchers may have found the reason for the sickness. The bedrock in the region consists of granites and volcanic rocks. These rock types contain elevated amounts of certain elements. The "sickness country" contains localized areas of unusually high natural levels of thorium, uranium, arsenic, mercury, fluorine, and radon in groundwater and drinking water. The aborigines had also used ochre as color pigment in painting. The ochre was shown to contain extremely high contents of uranium, lead, arsenic, and mercury. The naturally high levels of toxic elements in the land and water systems thus constitute a health hazard recognized eons ago by the local people. There can also be potentially hazardous exposure to natural gases such as radon. Geology is the most important factor controlling the source and distribution of radon. Relatively high levels of radon emissions are associated with particular types of bedrock and unconsolidated deposits, for example some, but not all, granites, phosphatic rocks, and shales rich in organic materials. The release of radon from rocks and soils is controlled largely by the types of minerals in which uranium and radium occur. Radon levels in outdoor air, indoor air, soil air, and ground water can be very different. Radon released from rocks and soils is quickly diluted in the atmosphere. Concentrations in the open air are normally very low and probably do not present a hazard. Radon that enters poorly ventilated buildings, caves, mines, and tunnels can reach dangerously high concentrations.

Naturally Occuring Organic Compounds in Drinking Water Balkan endemic nephropathy (BEN) is an irreversible kidney disease of unknown origin, geographically confined to several rural regions of Bosnia, Bulgaria, Croatia, Romania, and Serbia. The disease occurs only in rural areas, in villages


located in alluvial valleys of tributaries of the lower Danube River. It is estimated that several thousand people in the affected countries are currently suffering from BEN and that thousands more will be diagnosed with BEN in the next few years. Many factors have been proposed as etiological agents for BEN, including: bacteria and viruses, heavy metals, radioactive compounds, trace element imbalances in the soil, chromosomal aberrations, mycotoxins, plant toxins, and industrial pollution (Tatu et al., 1998). Recent field and laboratory investigations support an environmental etiology for the disease, with a prime role played by the geological background of the endemic settlements (Feder et al., 1991; Tatu et al., 1998; Orem et al., 1999). In this regard, there is a growing body of evidence suggesting the involvement of toxic organic compounds present in the drinking water of the endemic areas. These compounds are believed to be leached by groundwater from low rank Pliocene lignite deposits, and transported into shallow household wells or village springs. Analysis of well and spring water samples collected from BEN endemic areas contain a greater number of aliphatic and aromatic compounds, and in much higher abundance (>10x), compared to water samples from nonendemic sites. Many of the organic compounds found in the endemic area water samples were also observed in water extracts of Pliocene lignites, suggesting a possible connection between leachable organics from the coal and organics in the water samples. The population of villages in the endemic areas uses well/ spring water almost exclusively for drinking and cooking, and is therefore potentially exposed to any toxic organic compounds in the water. The presumably low levels of toxic organic compounds present would likely favor relatively slow development of the disease over a time interval of 10 to 30 years or more. The frequent association of BEN with upper urinary tract (urothelial) tumors suggests the action of both nephrotoxic and carcinogenic factors, possibly representing different classes of toxic organic substances derived from the Pliocene lignites. Pliocene lignites are some of the youngest coals in the Balkans and are relatively unmetamorphosed in the endemic areas. They retain many of the complex organic compounds contained in the decaying plant precursors (Feder et al., 1991; Orem et al., 1999), and many kinds of potentially toxic organic compounds may be leached from them. In the Pliocene lignite hypothesis for BEN etiology, however, other factors besides the presence of low rank coals must also be in play. The hypothesis also implies many or all of

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the following circumstances: the right hydrologic conditions for leaching and transport of the toxic organic compounds from the coal to the wells, a rural population largely dependent on untreated well water, a population with a relatively long life span (BEN commonly becomes manifest in people in their 40s and 50s), a relatively settled population for long exposure to the source of nephrotoxic/carcinogenic substances, and a competent and established medical network for recognition of the problem and proper, systematic, diagnosis. It may be that BEN is a multifactorial disease, with toxic organics from coal being one necessary factor in the disease etiology. The challenge to researchers is to integrate studies among disparate scientific disciplines (medicine,

epidemiology, geology, hydrology, geochemistry) in order to develop a reasoned conceptual model of the disease etiology of BEN.

Naturally Occuring Dusts Exposure to mineral dusts can cause a wide range of respiratory problems. These exposures can be due to local conditions such as the dusts generated by mining hard rocks or coal, use of fine-grained mineral matter in sand-blasting, and formation of smoke plumes from fires (both natural and man-made). Dust exposure can affect broad regions such as the dust stirred up by earthquakes in the arid regions of the southwestern U.S. and northern Mexico. This dust carries spores of a fungus (coccidiomycosis immetus) that causes

Figure 3: This satellite image shows a dust cloud from North Africa moving across the Atlantic Ocean, over northern South America and then over the Caribbean and the southern U.S. These dust storms occur several times a year resulting in increased incidence of asthma and allergies in the Caribbean region. The dust is not exclusively fine mineral grains. Researchers have found more than 140 different organisms hitchhiking from Africa to the Western Hemisphere.

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Valley Fever, a serious respiratory problem that can lead to fatigue, cough, fever, rash, including damage to internal organs and tissues such as skin, bones, and joints. Dust exposure can even take on global dimensions. Ash ejected form volcanic eruptions can travel many times around the world and recent satellite images have shown wind blown dust picked up from the Sahara and Gobi deserts blown halfway around the world. Of greatest concern for effects upon human health are the finer particles of the respirble (inhalable) dusts. On this regard, considerable work is beung conducted in identifying dust particles derived from soils, sediments and weathered rock surfaces. Asbestos is a term that represents a diverse group of minerals that have several common properties; they separate into long thin fiber, are heat resistant, and are chemically inert. In the 1980s it was recognized that exposure to respirable asbestos fibers can cause severe health problems such as mesothelioma, lung cancer, and asbestosis. Many mines producing commercial asbestos were closed and a concerted effort was made to remove asbestos from schools, work places, and public buildings. Unfortunately, the problem did not end there. Recently, it was found that small amounts of asbestos associated with commercial deposits of vermiculite, a micaceous mineral used for insulation, packaging, kitty litter, and other applications, had caused significant health problems in the mining community of Libby, Montana, USA (Van Gosen and others, 2002). Lung abnormalities (such as pleural thickening or scarring) occurred in about 18 percent of the adults tested.

Conclusions Medical Geology should be considered as a component of Malaysia's National Health Action Plan (NEHAP; Pillay et al., 2003). Pillay et al. state that "Environmental health is the science of protecting human health from the damaging effects of physical, chemical and biological agents in the environment. This science strives to identify harmful agents, determining exposures relating to deteriorating health conditions and to develop sound principles, strategies, programs and approaches to eliminate or minimize health risks." Medical Geology has the same objectives but focuses on the naturally occurring physical and chemical agents in the environment. Thus, for NEHAP to be most effective the Malaysian geoscience community should be included as one of the key players or agencies involved in environmental health activities.


References 1.

Belkin, H.E., Zheng, B., Zhou, D., and Finkelman, R.B., 1997, Preliminary results on the Geochemistry and Mineralogy of Arsenic in Mineralized Coals from Endemic Arsenosis in Guizhou Province, P.R. China: Proceedings of the Fourteenth Annual International Pittsburgh Coal Conference and Workshop. CD-ROM p. 1-20.

2.

Belkin, H. E., Kroll, D., Zhou, D.-X., Finkelman, R. B., and Zheng, B., 2003, Field test kit to identify arsenic-rich coals hazardous to human health. Abstract in Natural Science and Public Health Prescription for a Better Environment. U.S. Geological Survey Open-file Report 03-097. Unpaginated.

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27

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28


Abstracts

Can We Use Fixed Ambient Air Monitors to Estimate Population Long-term Exposure to Air Pollutants? The Case of Spatial Variability in the Genotox ER Study Éléna Nerriere1, Denis Zmirou-Navier1, Olivier Blanchard2, Isabelle Momas3, Joël Ladner4, Yvon Le Moullec5, Marie-Blanche Personnaz6, Philippe Lameloise7, Véronique Delmas8, Alain Target9 and Hélène Desqueyroux10 INSERM, Faculté de Médecine, School of Medicine, 9 avenue de la Forêt de Haye, BP 184-54 505 Vandoeuvre-les-Nancy Cedex, France 2 INERIS, Parc Technologique ALATA, 60 550 Verneuil-en-Halatte, France 3 Faculté de Pharmacie Paris 5, 4 avenue de l’Observatoire, 75 006 Paris, France 4 Département d’Epidémiologie et Santé Publique, CHU, 76000 Rouen, France 5 Laboratoire d’Hygiène de la ville de Paris, 11 rue George Eastman, 75 013 Paris, France 6 ASCOPARG, 44 avenue Marcellin Berthelot, BP 2734, 38 037 Grenoble Cedex 2, France 7 AIRPARIF, 7 rue Crillon, 75 004 Paris, France 8 Air Normand, 21 avenue de la Porte des Champs, 76 000 Rouen, France 9 ASPA, 5, rue de Madrid, 67309 Schiltigheim Cedex, France 10 ADEME, 27 rue Louis Vicat, 75 737 Paris Cedex 15, France 1

Abstract: Associations between average total personal exposures to PM2.5, PM10, and NO2 and concomitant outdoor concentrations were assessed within the framework of the Genotox ER study. It was carried out in four French metropolitan areas (Grenoble, Paris, Rouen, and Strasbourg) with the participation, in each site, of 60–90 nonsmoking volunteers composed of two groups of equal size (adults and children) who carried the personal Harvard Chempass multipollutant sampler during 48 h along two different seasons (“hot” and “cold”). In each center, volunteers were selected so as to live (home and work/ school) in three different urban sectors contrasted in terms of air pollution (one highly exposed to traffic emissions, one influenced by local industrial sources, and a background urban environment). In parallel to personal exposure measurements, a fixed ambient air monitoring station surveyed the same pollutants in each local sector. A linear regression model was accommodated where the dependent pollutant-specific variable was the difference, for each subject, between the average ambient air concentrations over 48 h and the personal exposure over the same period. The explanatory variables were the metropolitan areas, the three urban sectors, season, and age group. While average exposures to particles were underestimated by outdoor monitors, in almost all cities, seasons, and age groups, differences were lower for NO2 and, in general, in the other direction. Relationships between average total personal exposures and ambient air levels varied across metropolitan areas and local urban sectors. These results suggest that using ambient air concentrations to assess average exposure of populations, in epidemiological studies of long-term effects or in a risk assessment setting, calls for some caution. Comparison of personal exposures to PM or NO2 with ambient air levels is inherently disturbed by indoor sources and activities patterns. Discrepancies between measurement devices and local and regional sources of pollution may also strongly influence how the ambient air concentrations relate to population exposure. Much attention should be given to the selection of the most appropriate monitoring sites according to the study objectives. Keywords: PM2.5; PM10; NO2; Personal exposure; Ambient air quality monitoring

Original Source: Environmental Research Vol. 97, Issue 1 (2005) 32 - 42.. 30


Information for Authors

The purpose of the Environmental Health Focus (EH Focus) includes promoting research and development, translating research outcomes, engaging and equipping stakeholders both locally and regionally in the Environmental Health Action Planning (EHAP) purpose, and to achieve sustainable living within Malaysia and Asia Pacific. The EH Focus aims to engage a broad spectrum of people in dialogue. Thus, it applies both formal and informal and technical styles. The Editor will seek authors’ cooperation to insert endnotes in technical papers to broaden their readability.

Instruction to Authors The EH Focus is published twice per year, with two issues per volume, in March and October each year. The EH Focus accepts articles, research papers, news and views in relation to environmental health which have not been published previously. All articles submitted will be sent for refereeing and the decision of the editorial board as to the suitability of the article for publishing will be final. Neither the Editorial Board nor the Publisher accepts responsibility for the views and statements of authors in the paper. Manuscripts in English should be submitted in soft copy (preferably MS Word) with the hardcopy of the article send by mail. Manuscripts should be typewritten on A4 size paper and double-spacing throughout. Articles for Feature Articles, Technical Notes, research papers and literature reviews must be accompanied by abstracts of not more than 300 words in English. Supplementary abstract in author’s national language could be published above the English version if there is a request. Figures and tables should be submitted in original electronic form (e.g. MS Excel for table). References List all references at the end of the paper, following the Harvard system of referencing, as shown in the following examples. a)

Books Pescod, M.B. (1989). Environmental Engineering. Wiley. London. pp 123-124. Pescod, M.B. and Mara, D. (1987). Sewage Treatment. In Pescod, M.B. (Ed), Water and Wastewater Treatment. Wiley. London. pp 135-155.

b)

Journal Wakeman, R.A. (1989). Ultrasonic Cleaning of Membrane Processes. Journal of Membrane Science, 3(2):34-41.

c)

Conference Papers Suleyman, A.M. (1999). Use of Morringa Oleifera as Coagulant in Water Treatment. Proceedings of the International Conference on Water Treatment. Sarawak, Malaysia, pp 139-145.

Listing of authors should be in the following sequence, i.e. primary author, major contributor and supporting authors.

Think Globally... EH Focus is designed to engage our global neighbourhood in managing the environment for health in the AsiaPacific. This is not just a journal – it is a public conversation! The publishers invite you to interact on these pages to shape Environmental Health Action Planning (EHAP) in our region. We need to capture the big picture and look at it together, charting a sustainable future for our countries. Regional, national and local partnerships are the way to promote change and build our common destiny. You are invited to contribute as a way of starting our global conversation. Then let’s talk to the rest of the world!

You have a choice of interacting in these ways: • Publishing scene-setting articles to promote interaction between stakeholders. • Exchanging news and views. • Sharing feature articles to probe the future and challenge each other to think. • Being neighbourly by sharing success stories in case studies from local communites and with collaborating agencies. • Expressing opinions to shape EHAP thinking around Policy, Practice, Communitites and Research. • Keeping us abreast of your research with technical notes. • Offering research papers to which editors will add explanatory endnotes for non-technical readers. • Reviewing the literature in books and periodicals.

...Act Locally

Healthy communities are places where: • children are nurtured in body and mind • people work and age with dignity • environments support learning and leisure • ecological balance is a source of pride Adapted from WHO Yanuca Island Declaration (1995)