The study of the adverse effects of chemicals on the body.
Toxicologists z
Trained to examine the nature of the adverse effects of toxins and to assess the probability of their occurrence.
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Types of Toxicologists – Descriptive – Mechanistic – Regulatory
Routes of Exposure z
Inhalation-Most important for occupational settings.
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Ingestion-Most important route with small children.
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Absorption-Can be greater route then inhalation.
Possible Toxicological Effects Allergy-sensitization z Cancer z Central nervous system effects z Organ damage (liver, kidney) z Skin damage z Blood damage z Reproductive difficulties z
Vocabulary z
Poisons
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Tolerance
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Dose
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Dose-Response
Poisons z
Any agent capable of producing a deleterious response in a biologic system.
Poisons z
All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy. Paracelsus
Tolerance z
Decreased responsiveness to the toxic effect of a chemical resulting from prior exposure to the chemical or related chemical. By: – Decreased amount reaching target site or, – Reduced responsiveness of the tissue to the chemical.
Dose
z Used
to express the amount of exposure to a chemical.
Dose-Response z
Describes the response of an individual to varying doses of a chemical.
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Characterizes the distribution of responses to different doses in a population of individuals
Indices of Dose-Response z
LD50 -- Lethal dose for 50% of the population tested. (measured in mg/kg)
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TD50 -- Therapeutic dose
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ED50 -- Effective dose
Vocabulary Continued z
Potency
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Acute
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Chronic
Vocabulary Continued z
Carcinogens
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Teratogens
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Mutagens
Vocabulary continued z
Risk
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Risk Assessment
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Risk Management
Risk z
Risk-the probability that a substance will harm under specific conditions.
Risk Considerations z z z z z z z
Beneficial vs. Harmful aspects Effect immediate vs. Effect delayed No alternatives vs. Many alternatives Voluntary vs. Involuntary Exposure essential vs. Nonessential Affects Average people vs. Sensitive Know risk vs. Unknown risk
Risk Considerations z z z z z
Common (comfortable) vs. Dreaded Occupational vs. Nonoccupational Used as Intended vs. Misused Consequences Reversible vs. Irreversible Adult vs. Child
Occupational Risk Management z
Primary considerations used in occupational settings: – Voluntary vs. Involuntary – Affects Average People vs. Sensitive – Beneficial vs. Harmful
Toxicology of 3 Known Hazards z
Tobacco
z
Asbestos
z
Lead
Tobacco z z
Plant which grows in a wide range of soils, making it a good money making crop. Contains more over 4,000 chemical compounds. Including: – Nicotine – Tar – Cyanide – Produces carbon monoxide
– Ingestion • Residual from cigarettes swallowed • Smokeless tobaccos
Physiological Effects of Tobacco Addiction z Cancer z Chronic bronchitis z Worsened allergic conditions z Emphysema z Heart disease z Teratogen z
Tobacco z
As an addictive substance – As addictive as heroine and cocaine. – 75% of adolescence are still smoking daily seven to nine years later. – Young people do not believe they will become addicted.
Tobacco z
As a carcinogen – Small amounts of DNA-reactive carcinogens; however acts as an enhancing factor or promoter. – Promoters facilitate growth of a latent or already existing cancer cell into a tumor.
Tobacco z
Identified in the following cancers: – Lung – Esophageal – Bladder – Pancreatic – Liver
Tobacco z
Role in emphysema – Chemicals cause damage to the tiny airsacs in the lungs resulting in broken sacs and scarring reducing the bodies ability to exchange oxygen and carbon dioxide. – Eventually this will lead to death.
Tobacco z
Role in asthma and chronic bronchitis: – Immediately attacks lung tissue causing respiratory irritation and increased immune activity. – Results in chronic coughing and reduced breathing or asthma from tissue damage.
Tobacco z
Role as a teratogen: – Smoking elevates maternal blood levels of carboxyhemaglobin. – Carboxyhemaglobin is amplified in fatal blood. – Results in spontaneous abortions, stillbirths, premature births and low birth weight.
Tobacco z
Role in passive smoking: – Side stream – Exhaled smoke – Hazards
Asbestos z
Naturally occurring mineral which comes in two forms: – Serpentine: • Chrysotile
– Amphibole: • Amosite • Crocidolite
Asbestos z
Sources – Occupational • Insulating materials • Acoustical materials • other building materials – Flooring – gaskets – roofing
Diseases: – Asbestosis – Lung cancer – Mesothelioma
Asbestos z
Asbestosis: – Scarring of the lungs. – Due to immune response of macrophages. – Reduces breathing capacity. – Irreversible. – Severe cases lead to death.
Asbestos z
Lung Cancer – Exposed people 5 times more likely – Synergistic effect with cigarette smoking • 50 times more likely to develop cancer
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Mesothelioma – Cancer of the lining around the lungs – Only associated with asbestos exposure – Always fatal
Lead z
Lead is a naturally occurring metal used in: – Paints – Glazes – Solders – Gasoline
Carcinogenic Effects: – Some implications – Association remains uncertain
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Other Effects: – Effects on other body systems and organs
Facts z
Tobacco
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Asbestos
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Lead
Discussion z
What risk factors are considered for use or avoidance (control) of the three materials discussed. – Voluntary vs. Involuntary – Occupational vs. Nonoccupational – Benefits vs. Harm
Discussion – Risks known vs. Unkown – Adult vs. Child – Many alternitives vs. Few or none
