ExposureofthefetustohighlevelsofmercuryinuteromayleadtoMinamatadisease,characterizedbycerebralpalsy,deafness,andblindness.
Arsenicisnaturallyfoundinsoilandwaterandisacomponentofsomewoodpreservativesandherbicides.ExcessarsenicinterfereswithmitochondrialoxidativephosphorylationandcausestoxiceffectsintheGItract,CNS,andcardiovascularsystem;long-termexposurecausespolyneuropathy,skinlesionsandcarcinomas.
Cadmiumfromnickel-cadmiumbatteriesandchemicalfertilizerscancontaminatesoil.Excesscadmiumcausesobstructivelungdiseaseandkidneydamage.
More than 10 million occupational injuries occur annually in the United States, and approximately 65,000 people die as a consequence of occupational injuries and illnesses. Industrial exposures to toxic agents are as varied as the industries themselves. They range from merely annoying irritations of respiratory airways by formaldehyde or ammonia fumes, to lung cancers arising from exposure to asbestos, arsenic, or uranium. Human diseases associated with occupational exposures are listed in
Table 8.2 . In addition to toxic metals (already discussed), other important agents that contribute to environmental diseases include the following:
Organic solvents are widely used in huge quantities worldwide. Some, such as chloroform and carbon tetrachloride, are found in degreasing and dry cleaning agents and paint removers. Acute exposure to high levels of vapors from these agents can cause dizziness and confusion, leading to CNS depression and even coma. Lower levels may cause liver and kidney toxicity. Occupational exposure of rubber workers to benzene and 1,3-butadiene increases the risk of leukemia. Benzene is oxidized to an epoxide through hepatic CYP2E1, a component of the P-450 enzyme system already mentioned. The epoxide and other metabolites disrupt progenitor cell differentiation in the bone marrow, and may lead to marrow aplasia and acute myeloid leukemia.
Polycyclic hydrocarbons are released during the combustion of coal and gas, particularly at the high temperatures used in steel foundries, and also are present in tar and soot. (Pott identified soot as the cause of scrotal cancers in chimney sweeps in 1775, as mentioned in Chapter 6). Polycyclic hydrocarbons are among the most potent carcinogens, and industrial exposures have been implicated in the causation of lung and bladder cancer.
Organochlorines (and halogenated organic compounds in general) are synthetic products that resist degradation and are lipophilic. Important organochlorines used http://ebooksmedicine.net
Table 8.2 Human Diseases Associated With Occupational Exposures
CardiovascularsystemHeartdiseaseCO,lead,solvents,cobalt,cadmium
UrinarysystemToxicityMercury,lead,glycolethers,solventsBladdercancerNaphthylamines,4-aminobiphenyl,benzidine,rubberproducts
HematopoieticsystemLeukemiaBenzene,radon,uranium
SkinFolliculitisandacneiformdermatosisPolychlorinatedbiphenyls,dioxins,herbicidesCancerUltravioletradiation