Lead: ongoing public and occupational health ... - Oxford Journals

Journal of Public Health | Vol. 34, No. 2, pp. 176 –182 | doi:10.1093/pubmed/fdr077 | Advance Access Publication 27 September 2011

Lead: ongoing public and occupational health issues in vulnerable populations: a case study I. Kar-Purkayastha1, S. Balasegaram2, D. Sen3, A.J. Rehman4, P.I. Dargan5, D. Johnston2, A. Raynal3, D.M. Wood5, A. Abrahams2, R. Kamanyire1, V. Murray1, R. Cordery2 1

Centre for Radiation, Chemicals and Environmental Hazards London, Health Protection Agency, London SW1W 9SZ, UK North East and North Central London Health Protection Unit, Health Protection Agency, London SW1W 9SZ, UK 3 Health and Safety Executive, Bootle, Merseyside, UK 4 Medical and Occupational Health Services, 117a Harley Street, London W1G 6AT, UK 5 Guy’s and St Thomas’NHS Foundation Trust and King’s Health Partners, London SE1 9RT, UK Address correspondence to I. Kar-Purkayastha, E-mail: [email protected] 2

A B S T R AC T Background Lead has been recognized increasingly as a public health risk, although with the introduction of wide-ranging occupational and public health measures, levels of blood lead in the general population of the UK and other developed nations have been in decline in recent years. Nonetheless, cases of lead poisoning still occur. Methods We report on a large cluster of exposed lead workers and their families, including several children. The focus of the occupational and public health investigations was to identify the different groups at risk and the pathways by which potential exposures were taking place. Results Lead in the workplace was found to account for the raised blood lead levels amongst the workers with exposure occurring as a result of insufficient demarcation between ‘clean’ and ‘dirty’ areas, and from contamination of personal belongings with lead. Furthermore, there was evidence of para-occupational exposure of family members. Conclusions The successful control of lead in this case required multidisciplinary working. Efforts included extensive workplace controls, along with the education and care of workers and their families, though complicated by lack of familiarity with the UK health service amongst the affected groups, language barriers, underlying low levels of literacy and high mobility. Keywords occupational diseases, public health, social determinants

Introduction I. Kar-Purkayastha, Specialist Registrar Public Health Medicine

Lead is recognized as a public health hazard. Although clinical features are often not seen in adults at blood lead concentrations below 40 mg dl21, subclinical effects at lower concentrations may occur particularly in cognition and within the cardiovascular and renal systems.1 – 4 In children, cognitive deficits have been demonstrated at concentrations as low as 2 mg dl21 and recent evidence suggests that there is no minimum safe level of exposure in children.5 – 8 Today, lead remains widely distributed in the environment due to industrial emissions as well as prior use of lead in fuels, paint and water pipes.1,9 The introduction of wide-

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S. Balasegaram, Consultant in Health Protection D. Sen, Consultant & Honorary Senior Lecturer in Occupational Medicine A.J. Rehman, Consultant in Occupational Medicine P.I. Dargan, Consultant Clinical Toxicologist D. Johnston, Foundation Year Doctor, Public Health Medicine A. Raynal, Consultant in Occupational Medicine D.M. Wood, Consultant Clinical Toxicologist A. Abrahams, Health Protection Nurse Specialist R. Kamanyire, Unit Head, Centre for Radiation, Chemicals and Environmental Hazards London V. Murray, Unit Head, Extreme Events and Health Protection Section R. Cordery, Consultant in Health Protection

# The Author 2011, Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved.

L E A D : O N G O I N G P U B L I C A N D O C C U PAT IO N A L H E A LT H I S S U E S

ranging occupational and public health measures has seen a decline in levels of blood lead in the general population of the UK10,11 and other developed nations such as the USA in recent years.12 – 15 Nonetheless, cases of lead poisoning still occur in the UK16 – 18 and in the USA.19 Worldwide, recent outbreaks have been seen in China20 and Nigeria.21 Amongst UK adults, cases occur predominantly in an occupational context; amongst children, exposure is commonly from household sources such as lead in household dust, soil and flaking lead-based paints.22,23 Lead uptake resulting from second-hand exposure amongst family members of those working with lead, i.e. para-occupational exposure, has also been recognized for some time.24 – 28 In the UK, the legal responsibility for preventing workrelated ill health in occupational settings is shared, depending upon the setting, between the Health and Safety Executive (HSE) and the Local Authority. The Control of Lead at Work Regulations 2002 requires employers to manage lead exposure caused through work and in the workplace. The responsibility for the health of the general public currently lies with the local Primary Care Trust (PCT) and the Health Protection Agency (HPA). This paper describes a cluster of lead toxicity in employees at a UK metal recycling plant, with secondary cases amongst household contacts, explores the difficulties in investigation and management of such cases and demonstrates the importance of a multidisciplinary approach.

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work clothes—although work overalls were issued and laundered by the company, employees were found to be taking dirty overalls home to be washed and significant lead contamination of some of the employees’ personal belongings were found in the main changing room, suggesting that these were in direct contact with lead contaminated surfaces. Thus, exposure pathways for lead dust to be transported into employees’ homes were identified and necessitated further public health action. Clinical The occupational health assessment involved blood lead measurements in 92 employees involved in the de-sheathing of lead encased telephone cables. Ninety workers were found to have a blood lead level (BLL) of .10 mg dl21, of whom 25 (over a quarter) were classed as Category E, mandating suspension from work and further exposure under Regulations.29 (In adult males, Category E corresponds to a BLL of 60 mg dl21.and over.) Two distinct at-risk groups were identified: (i) workers at the plant and (ii) their household contacts. Subsequent investigation and management required joint working between the HPA and the HSE, along with clinical toxicologists, occupational health services, the local council and PCT. Table 1 gives a timeline for the investigation. The occupational health assessment was initially delayed by the Employer in finding a suitable HSE appointed doctor (as required under the lead regulations) to carry out the statutory medical surveillance of workers on site.

Occupational health Investigation

The initial workplace-based investigation was prompted by a routine HSE visit to the site where telephone cables were being recycled using a relatively simple process in which lead-lined copper cables were being split and separated. All processes were ‘cold’, i.e. no heat was involved to generate lead fumes, and the main risk to health was from the dust generated. However, the HSE visit identified unsafe work practices and the company was requested to obtain occupational health input. Findings

Environmental The two principal HSE concerns were: the lack of clear demarcation between ‘clean’ and ‘dirty’ areas—employees were eating, smoking and drinking in parts of the site that were contaminated, thus potentially ingesting lead; and lack of clear protocol with respect to changing into and out of

Public health Investigation

Staff from the local Health Protection Unit (HPU) and the Centre for Radiation, Chemicals and Environmental Hazards (CRCE) London, both within the HPA, undertook an initial site visit of the metal recycling plant and their inspection confirmed previous HSE findings that pathways did exist for lead dust to be transported into employees’ homes but also that there were no other obvious routes of exposure for the wider public. The sequential public health investigation that followed included the clinical assessment and biological monitoring of family and household members; and environmental investigation at the home of the affected family. Assessment of household contacts The local HPU and PCT organized the clinical assessment through a health questionnaire and serological screening of

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J O U RN A L O F P U B L I C H E A LTH

Table 1 Timeline charting progress across the two complimentary aspects of the investigation Date (2009)

Stage

April

HSE site visit to metal recycling plant

Key outcomes

Lead agency

Unsafe work practices identified and occupational health input

HSE

requested Control measures instituted and advice given on minimizing further lead exposure July August

Occupational health assessment of

90 of 92 workers deployed in the recycling of metal found to have

workers

elevated blood lead levels (BLL)

Health/HSE

Clinical toxicology review of workers with

Chelation therapy given to symptomatic patients

NHS Acute Trust

highest blood lead concentrations September

HPA site visit to metal recycling plant

Occupational

Specialty Clinic Confirmation of existence of potential exposure pathways for

HPA

household members, possibility of para-occupational exposure and need for screening families October/

Organization of clinics for assessment of

Identified three children with raised BLL of whom two had levels

November

high-risk family members with blood

sufficiently high to require paediatric follow-up

HPA and PCT

testing October

Home visit to child’s home

No alternative sources of lead identified

HPA and EHD of LA

Ongoing

Further screening of workers

Difficulties in controlling BLLs in a few workers, despite control

HSE/Occupational

measures being instituted. Ongoing HSE input to correct this

Health

families and household contacts of workers in clinics held at a community health-care facility. Invitations were restricted to contacts meeting the assessment criteria, i.e. those deemed at highest risk of and from exposure. These were vulnerable household contacts of workers who had a BLL of .60 mg dl21 and were symptomatic; contacts considered vulnerable included young women of child-bearing age, pregnant women and children. For the first round of screening, 14 individuals were invited to participate. Figure 1 shows how contacts were selected and participated in screening in the first round. It was intended that screening would be extended to a wider group if there was evidence of secondary exposure in this highest risk group. Environmental investigation in the home The environmental assessment was carried out by the local HPU and the Environmental Health Department (EHD). A comprehensive assessment of potential sources of lead within the home was made using a tailored questionnaire developed by CRCE.30 A thorough visual inspection of the property was carried out and multiple environmental samples were taken. Findings

Population characteristics The affected workers and their families were from one European immigrant group and many were not registered

with local general practitioners (GPs). They were a mobile, temporary population, some only visiting the UK, but other spending longer periods in households with multiple families. Most of the clinic attendees were unable to speak English; information sheets and consent forms were translated and an interpreter was present at each session. Findings from the different stages of the public health investigations are described below. Assessment of family and household members Of those eligible, only nine attended for assessment in the first round of screening. These individuals did not show any clinical evidence of lead toxicity. However, blood tests showed that three children from two separate households had BLLs above the population norm. The current UK reference range for lead is ,10 mg dl21 and the population norm is 1 –2 mg dl21, so it was felt that two of the three children with levels of 5 and 11 mg dl21, respectively, had significant lead exposure and were referred for paediatric assessment. These assessments did not show any evidence of adverse clinical features related to lead. Environmental investigation in the home The HPU and local EHD organized a visit to the home of the child with the BLL of 11 mg dl21. The child was 7 months old at the time of the investigation, had been born in the UK and had not lived


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Employees n=92 Employees with BLL 50–60 mg dl–1 (action taken–monitor BLL) n=24

Employees with BLL >60 mg dl–1* (action taken: suspension) n=25

Employees with BLL between 10 mg dl–1 and 50 mg dl–1 (no further monitoring) n=43

Employees with lead poisoning (BLL >60 mg dl–1 and symptomatic n=6 (out of 25)

26 household contacts meeting assessment criteria

13 children 13 adult females

3 no longer resident in the UK

8 reside in London: Screen

7 no longer resident in the UK

6 reside in London: Screen

2 unable to locate 4 children attended for first round of screening

5 adult females attended for first round of screening

Fig. 1 Selection and participation of household contacts in the first round of assessment and screening. *BLL . 60 mg dl21 is the level at which adult males are suspended from work; specific thresholds are in place for females and under 18s.

anywhere besides their current address. The house was a small terraced house with 11 occupants. It was well maintained and no additional sources of lead in the home were identified. At the time of the investigation, the child’s father was working as a painter, though he had been working at the recycling plant until 1 month prior to the home visit. Whilst at the plant, he wore home clothes to work, changed at work and changed back into his home clothes to come home. He would then shower at home when he came in. He brought his work clothes home to be washed, once per week but always carried them home in a dedicated bag. Analysis of environmental samples from the home showed that dust from the vacuum cleaner contained a significantly

raised lead content which supports the hypothesis that lead dust was being brought into the home on the employee’s person.

Actions taken Based on the findings of the occupational and public health investigations, the workplace was confirmed as the location at which control measures were necessary in order to prevent both first-hand and second-hand exposure to lead. As a first measure in the control of the hazard, a new workplace protocol was instituted. This consisted of rigid separation of the workplace into ‘clean’ and ‘dirty’ zones,

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stepped change from home clothes to work clothes. A drinks machine was available for use in the ‘dirty’ area, with disposable cups but only accessible after hands had been washed; other than that no eating or smoking was allowed within the ‘dirty’ zone and employees were required to decontaminate (thorough washing of hands and arms) and change into a clean set of ‘work’ clothes prior to transferring out of the ‘dirty’ areas. Eating was permitted only in the ‘clean’ canteen area. Despite these initial measures, ongoing monitoring showed only a very slow decline in blood lead levels. Over the following months, a number of further measures were put into place: upgrading of washing facilities and decontamination protocol to full shower instead of washing of arms and hands; use of extractor fans in the warehouse; re-deployment of workers and for those with the highest BLLs suspension from activities with potential further exposure to lead; and implementation of a continuous programme of health education. It was not until a new ventilation system had been in place for a few months, however, with automation of part of the lead stripping process that blood lead levels were seen to stabilize and take a downward trend. These findings combined with evidence of second-hand exposure within households have necessitated the extension of the investigation. Both the occupational health and public health monitoring are likely to continue for the foreseeable future and have included further efforts to identify and screen at risk contacts including those who did not attend for the first round.

Discussion Main finding of this study

Ninety workers involved in the recycling of cables at a UK metal recycling plant were found to have BLL of .10 mg dl21, 25 with levels exceeding the legal occupational limit and therefore warranting suspension from work.29 The HSE site visit identified the potential for paraoccupational exposure. The subsequent clinical assessment and screening of high-risk household contacts identified three children with elevated BLLs, one of whom, a 7-month-old infant, had a BLL indicating significant lead exposure. No additional sources of lead exposure were identified. However, analysis of environmental samples from within the infant’s home showed that dust from the vacuum cleaner contained a significantly raised lead content. Although the family had taken measures to prevent exposure to the

father’s work clothes, based on findings from the home visit and workplace assessments, para-occupational exposure remained the most plausible explanation for elevated BLL in the child. By the time of the public health investigation, the baby’s father had already changed employment and was no longer working with lead. However, ongoing occupational health surveillance at the plant showed that amongst remaining employees, blood lead levels were very slow to respond to the hygiene measures that were being implemented. A likely contributing factor, later identified, was the communication of messages around the importance of hygiene-related behaviours: whilst health educational materials were being translated into appropriate languages, this did not take into account the underlying levels of literacy which were often low. What is already known on this topic

Cases of secondary exposure from occupational sources have been previously described in the literature.24 – 28 Children are particularly vulnerable due to increased dose relative to body weight, greater gut absorption and potentially irreversible developmental effects. The historically accepted threshold of toxicity is 10 mg dl21. However, a growing body of evidence suggests that cognitive deficits may occur even at lower levels in children with long-term effects on educational achievement.5 – 7 Lead exposure has also been positively associated with markers of lower socio-economic status such as low income.31,32 Risk factors for exposure to lead in the home include: living in older poorly maintained housing stock;14,31 living near industrial sites; and living in homes where there may be para-occupational exposure to lead (manual labour, construction work).24,25 In the USA, the highest prevalence of raised BLLs is seen amongst non-Hispanic black American children compared with other ethnic groups.12 What this study adds

The convergence of multiple vulnerabilities resulted in the cluster described in this paper: the affected individuals were all recent migrants involved in recycling and construction work and therefore at potentially greater risk of exposure to heavy metals, few had registered with GPs and many were unaware that as EU citizens, they were eligible. Workplace advocacy was needed to secure support from male family heads and further to encourage registration of workers and their household contacts with GPs and to undergo screening. Additional resources were required for translation and interpretation. Controlling exposure to lead in the workplace setting may be extremely difficult and, as was seen in this case,


communication difficulties, particularly written communication with non-English speaking workers, may be compounded by underlying low levels of literacy. Finally, this case highlighted the responsibilities of the various agencies for health in different contexts and the value of multiagency coordination, with the need for access through the workplace to recruit households for screening. This study also highlights an area where the need for more concerted public health action should be considered. In the UK, there are no surveillance mechanisms currently in place by which we can confidently describe the distribution of elevated BLLs in the population. This is particularly pertinent in view of the strong associations with deprivation, other markers of lower educational achievement and being from minority groups. It is possible that the childhood incidence of raised BLLs in these groups is higher than that detected in the general population. In the USA, the Centers for Disease Control (CDC) recommend that all children enrolled in Medicaid and those identified as being at risk on the basis of state or local criteria be offered BLL testing by their healthcare providers.6 No such targeted screening programme exists in the UK, nor is any screening routinely offered to families at risk of para-occupational as seen in this case. Whilst the UK Health and Safety legislation seeks to protect the worker by controlling the hazard at source, there may be a case for additional screening of contacts. At the time of the investigation, no comparison was made of blood lead levels between household contacts of the affected workers and families living in the vicinity of the recycling plant or with families living further away (the general population). However, further epidemiological study of the prevalence of elevated BLLs in the UK children is currently being undertaken by the British Paediatric Surveillance Unit33 and may in future provide a useful epidemiological baseline, as well as informing screening decisions, in particular whether screening should target certain groups such as children with developmental and behavioural problems, as has been suggested by some authors.34

Limitations of this study

One of the major limitations was that the uptake rate for screening amongst household contacts was low. As the households tended to be large with frequent migration to and from the country of origin, some contacts could not be reached. Whilst an occupational source seemed most likely, possible alternative sources of lead exposure had to be investigated. As the workers were all from the same country, there was a possibility that the exposure had occurred prior to their

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arrival in the UK; secondly, many of the workers lived in large households, sometimes with more than one family in one house, which made the possibility of a common household, rather than workplace source, a real possibility.

Conclusions Lead is a well-known toxin; in children, exposure even at low levels can cause cognitive deficits, thus there is no safe minimum level of exposure in children. In the UK and many other developed countries, levels of lead in the environment have been declining due to public health measures such as the introduction of unleaded petrol. Nonetheless, cases still occur, often occupationally caused but then transferred second-hand to vulnerable groups including women, children and those from more deprived socio-economic groups. In the UK, there is no routine public screening for lead toxicity. However, targeted screening programmes do exist in the USA and have been called for in the UK in select groups such as in children with developmental and behavioural problems. This case highlights that another group at risk are children with possible para-occupational exposure. Whilst the current epidemiology of lead toxicity in the UK is not well characterized, the BPSU study will shed some light on this in the paediatric population and we recommend that clinicians and public health practitioners be aware of this potential threat to health. This paper highlights the difficulties of undertaking public health actions in a mobile, temporary population from one ethnic migrant group, with language barriers to overcome and many not registered with local GPs. As noted previously, this is not a new problem but is becoming more of an issue particularly with the expansion of the European Union and an increase in occupational migrants.35 The authors conclude that a successful outcome can only be achieved through good communication and collaboration between all agencies.

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