Occupational poisoning in the current clinical practice

Occupational exposure to chemicals has considerably changed over the years, both qualitatively and quantitatively, in connection with the technological progress, the disappearance of some jobs and the appearance of others, the adoption of better preventive measures with consequent elimination or reduction of some risks, the partial substitution of these latter with new risks. The recent issuing of the legislative decree 25/2002 (which integrates the known legislative decree 626/1994) imposes an accurate assessment of the risks deriving from the increasing number of chemicals utilized in the most disparate productive processes. With this in mind, and in the light of the case record of our institute, we believe useful to pinpoint the clinical aspects of occupational toxicology which are encountered nowadays in the hospital practice. •Some “classical” clinical pictures (e.g., florid saturnism, manifest hydrargyrism, benzene emopathy, sulphocarbonism, n-hexane neuropathy), deriving from chronic exposure to medium-high levels of workplace pollutants, have almost completely disappeared. •On the other hand, the risk of accidental acute poisoning (caused by pesticides, industrial solvents, gases, etc.) mantains its relevance. The victims of such accidents should always be accurately followed up, due to the possibility of long term sequelae (e.g., organophosphate neuropathy, carbon monoxide delayed encephalopathy) that may become evident after a period of apparent recovery. •Long latency, chemical-induced diseases (pneumoconiosis, occupational cancer) due to occupational exposures suffered in the past are still common. Since these illnesses usually reveal themselves several years after the exposure to the chemical hazard has ceased, occupational anamnesis plays a keyrole for their correct diagnostic identification. •The problem of the exposure to carcinogenic agents (e.g., asbestos, benzene, nickel, hexavalent cromium, polycyclic aromatic hydrocarbons) remains particularly relevant where the substitution of such substances in the productive processes is not practically feasible. Etiological diagnosis of occupational cancer is extremely difficult, with obvious implications in the medico-legal setting. •Especially in predisposed subjects, prolonged occupational exposure to low doses of chemicals can induce oligosymptomatic, aspecific clinical pictures (e.g., micromercurialism, subclinical plumbism, “chronic painter syndrome”), which may be misdiagnosed for diseases due to other causes (once again, a careful occupational anamnesis should be collected). Moreover, there is controversial evidence that occupational exposures to microdoses of chemicals participate in the etiopathogenesis of some neurodegenerative disorders (e.g., Parkinson’s disease, Alzheimer disease) which are usually labelled as “idiopathic”. •The threshold limit values (TLVs) currently adopted in the workplaces protect the majority of the exposed subjects, but not all of them. In other words, a minority of workers may be damaged from the exposure levels tolerated by their colleagues. Allergy is the best examplification of this concept. Indeed, skin and respiratory allergopathies are among the occupational diseases most frequently observed nowadays. Additionally, individual xenobiotic metabolism (linked to genetic, physiological and environmental determinants), or the congenital deficiency of some enzymes (such as glucose-6-phosphate dehydrogenase: G6PD), may cause hypersensitivity to specific toxicants (in the case of G6PD deficiency, to the action of hemolytic poisons) (3). Thus, the technical preventive measures and the observance of TLVs should always be flanked by medical interventions (sanitary surveillance, biological monitoring) aimed at protecting the health of every single worker. •Occupational toxicology is tightly linked to environmental medicine: pesticides and industrial chemicals often contaminate the natural environment and enter the food chains. Such perturbations may affect more or less directly the living beings, including humans. This is well examplified by the cases of mercury (fish contamination by methylmercury), benzene (risk of leukemia for the general population) and asbestos (“vicinity” mesothelioma).