Occupational exposure levels observed

Biological monitoring has been used to relate serum and urine chromium levels to occupational exposure levels. A statistically significant (r=0.95, p<0.001) relationship between total chromium exposure and urinary chromium concentrations at the end of the workday were observed in five welders exposed to chromium(VI) compounds. The urinary chromium concentrations of 40-50 pg/L immediately after work... 

Table II. Recently Observed Occupational Exposure Levels Work Place...

Whole blood may contain 1-2 /amalgam fillings and with low fish consumption (Svensson et al., 1987 and 1992 Molin et al., 1990a and 1991 Akesson et al., 1991). In persons with occupational exposure, levels ranging from 20-100/contaminated fish, levels above 500 pg/L have been observed (Birke et al., 1972 Skerfving, 1974). 

As well as the filter-specific maximum concentrations based on the adsorptive capacity, the rates of leakage of the used masks must also be considered. The following restrictions in regard to the occupational exposure levels are to be observed ... 

Data presented in Table 9 compare the Occupational Exposure Level (OEL) for a number of compounds detected in landfill gas and the maximum observed concentration for each. For each compound, the maximum observed concentration exceeds the OEL, in some cases by at least one order of magnitude. 

Haematoxicity, particularly pancytopenia (diminution of all formed elements in the blood), has been observed in both humans and animals following exposure to benzene [12, 13, 196, 198, 224, 242-248]. Benzene-induced pancytopenia and aplastic bone marrow indicate a greater risk to acute myelogenous leukaemia and erythroleukaemia [196]. The effect of increase in red blood cell levels of delta-aminolevulinic acid (a precursor in the haeme biosynthetic pathway) and the effect of decrease in the mean serum complement of the blood occur at benzene occupational exposure levels of 3-15 ppm, and may also have a potential significance [196]. According to a study of the hypofunction of different blood systems, disorders occur at benzene exposure rates of 2-500 ppm [3, 12, 13, 198]. Isolated cases of abnormal blood composition due to minimum exposure levels of 2-3 ppm have been reported from Italy and France [249, 250]. 

Chloracne and related skin problems have been observed in several groups of workers and it was suggested that the ak concentrations of commercial PCBs >0.2 mg/m were associated with this effect (62). It was also reported that after occupational exposure to PCBs was terminated there was a gradual decrease in the severity and number of dermatological problems in the exposed workers, and this paralleled a decrease in thek semm levels of PCBs (61). 

To calculate the safe re-entry interval (REI), the margin of exposure (MOE) must be considered. Worker risk is measured as a margin of exposure and is related to how closely the occupational exposure comes to the no observed adverse effect level (NOAEL, for oxamyl 50 mg kg day ). MOE is defined as... 

Increases in ALAS activity have been observed in lead workers (Meredith et al. 1978). Leukocyte ALAS was stimulated at a PbB level of 87 pg/dL (Meredith et al. 1978), a level at which ALAD activity is already significantly inhibited. ALAD activity correlated inversely with PbB levels in occupationally exposed individuals (Alessio et al. 1976 Wada et al. 1973), as has been seen in subjects with no occupational exposure (Secchi et al. 1974). Erythrocyte ALAD and hepatic ALAD activities were correlated directly with each other and correlated inversely with PbB levels in the range of 12-56 pg/dL (Secchi etal. 1974). 

Histopathological evidence of renal damage has been observed in lead-exposed workers. Renal ultrastructure and function were examined in five men with heavy occupational exposure to lead (Cramer et al. 1974). In addition, renal function was evaluated in two men from whom renal biopsies were not obtained. PbB levels ranged from 71 to 138 pg/dL. Renal function tests were normal in all except for a reduced glomerular filtration rate in one worker. Two subjects with relatively short exposure to lead (6 weeks and 8 months) and PbB levels of 89-129 pg/dL had intranuclear inclusions in the proximal tubules. Renal biopsies from workers with longer periods of lead exposure (4-20 years, PbB levels of 71-138 pg/dL) had diffuse interstitial or peritubular fibrosis. Glomeruli were normal in all subjects. 

In humans, severe cases of acrylonitrile poisoning have resulted in low grade anemia (Wilson 1944 Wilson et al. 1948), but complete recovery was reported. Chronic occupational exposure to low levels of acrylonitrile has not resulted in detectable effects on the hematological system (Sakurai et al. 1978). In intermediate and chronic studies in animals, decreased red cell count, hemoglobin concentration and hematocyte were observed (Bio/dynamics 1980a, 1980b, 1980c Quast et al. 

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