Poisoning occupational monitoring

Occupational pesticide poisonings have been considered a serious problem in Costa Rica for many years (e.g. Thrupp, 1989). The number of registered poisoning cases can be assumed to be lower than the actual number of poisonings as monitoring is based on voluntary information provided by poison victims and physicians. 

Diquat and paraquat are quaternary ammonium compounds largely used as contact herbicides and crop desiccants. When systemic absorption occurs, paraquat and diquat are rapidly distributed into the body. Paraquat primarily accumulates in the lungs and kidneys, while the highest diquat concentrations have been found in the gastrointestinal tract, liver, and kidneys (WHO, 1984). Urine is the principal route of excretion for both diquat and paraquat, which are primarily eliminated as unmodified compounds. Occupationally exposed workers can be monitored by measuring paraquat and diquat concentrations in urine samples (Table 6). Blood concentrations are useful to monitor acute poisoning cases. 

OPs have been in use for several decades as important chemicals for the control of crop pests. With their chemical and biochemical reactions, OPs have been well established as extremely poisonous chemicals. This classification is due to the inhibition of the marker enzyme ChE, which is produced in the liver. Blood enzymes provide an estimate of tissue enzyme activity. After acute exposure to OPs or a nerve agent, the erythrocyte enzyme activity most closely reflects the activity of the tissue enzyme. Once the OPs inhibit the tissue enzyme, it cannot hydrolyze ACh, and the accumulation stimulates the affected organ. Based on the manner of exposure (dose and duration) to different OPs, a series of toxicity signs and symptoms set in the organism, leading to death. These are important aspects to be closely monitored among pest control operators and occupational workers exposed to OPs. 

Dimethylacetamide is used as a solvent in the manufacture of plastics and as a paint remover. Occupational poisoning and hepatotoxicity to extreme eoneentrations of dimethylacetamide (DMA) are reported in the medical literature. Deereases in hepatie clearance measures and alterations in hepatic transaminases with hepatomegaly have been reported at lower doses.Like dimethylformamide, DMA is readily absorbed through the skin. Chronic exposures in workers exposed to low air concentrations of DMA of less than 3 ppm and with biological monitoring assessments to measure dosages by dermal absorption demonstrated little evidence of hepatotoxicity by clinical chemistries. "... 

This document outlines the medical monitoring program as defined by the occupational safety and health standard for inorganic lead. It reviews the adverse health effects of lead poisoning and describes the important elements of the history and physical examinations as they relate to these adverse effects. Finally, the appropriate laboratory testing for evaluating lead exposure and toxicity is presented. 

Measurements of blood Pb levels have been traditionally regarded as the best indicator of the risk of Pb poisoning and the most meaningful in monitoring workers exposed to Pb. Manifest symptoms of Pb toxicity in the occupationally exposed worker reirely occur at blood Pb levels below 80 [xg/dL. In a survey of 26 industrial operations conducted by the National Academy of Sciences, 10-35% of occupationally exposed workers had blood... 

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