Internal lead and cadmium exposure in 6-year-old children from western and eastern Germany

Lead and cadmium levels in blood and deciduous teeth (shed incisors only) of 6-year-old German children were determined in 1991 in a large epidemiological study carried out in rural and urban areas of western Germany (Duisburg, Essen, Gelsenkirchen, Dortmund, Borken) and eastern Germany (Leipzig, Halle, Magdeburg, Osterburg, Gardelegen, Salzwedel). In total, blood lead and cadmium levels of 2311 German children and tooth lead and cadmium levels of 790 German children were analyzed. Blood lead levels were generally low in all study areas with geometric means between 39.3 g/1 and 50.8 g/l in the western German and between 42.3 g/1 and 68.1 g/l in the eastern German study areas. The mean blood lead level of Turkish children (n = 213) living in the western German study areas was 50.1 g/l and thus 5.6 g/1 higher than the overall geometric mean of the western German children. The higher exposure may be explained by a higher oral uptake from food and different living conditions. These children were excluded from multiple regression analysis because they were all living in the western study areas. The mean tooth lead levels ranged between 1.50 and 1.74 g/g in the western and between 1.51 g/g and 2.72 g/g in the eastern study areas. Thus, they show a distribution pattern similar to blood. Blood and tooth lead levels were higher in urban than in rural areas and higher in the eastern German than in the western German study areas. With regard to the blood and tooth cadmium concentrations, no significant differences between the study areas could be found. The mean cadmium levels in blood ranged between 0.12 g/1 and 0.14 g/l and the mean tooth cadmium concentrations between 20.8 ng/g and 27.8 ng/g. Blood and tooth lead and cadmium levels of the eastern and western German children were thus mainly at a relatively low level in all rural and urban study areas. The study demonstrates and confirms that blood and tooth lead levels are influenced by several demographic, social, and environmental variables. The results indicate that there has been a further significant decrease of lead and cadmium exposure in western German children since our last epidemiological study carried out in the same study areas in 1985/1986.     

Exposure to lead and cadmium of children living in different areas of North-West Germany: results of biological monitoring studies 1982–1986

Summary Between 1982 and 1986 several surveys were carried out to determine the levels of lead and cadmium in blood, urine, and shed deciduous teeth (incisors only) of children living in rural, suburban, urban, and industrial areas of North-West Germany. Blood lead (PbB) and blood cadmium (CdB) were measured in about 4000 children. In rural, suburban and urban areas the median PbB levels vary between 5.5 and 7 g/dl, with 98th percentiles varying between 10 and 13 g/dl. The median CdB levels are between 0.1 and 0.2 g/dl, with 95th percentiles between 0.3 and 0.4 g/l. Children from urban areas have significantly higher PbB levels than children from rural and suburban areas. Regarding CdB no differences could be detected. Children living in areas around lead and zinc smelters, particularly those living very close to the smelters, have substantially increased PbB and CdB levels. Children from lead worker families also have substantially increased PbB and CdB levels. The lead levels in shed milk teeth (PbT) were determined in about 3000 children. In rural, suburban and urban areas the median PbT levels are between 2 and 3 g/g, with 95th percentiles between 4 and 7 g/g. Children from urban areas have significantly higher PbT levels than children from rural and suburban areas. The highest PbT levels (on a group basis) are in children from nonferrous smelter areas. The median levels of lead in urine (PbU) are between 6 and 10 g/g creatinine, with 95th percentiles between 20 and 30 g/g creatinine. Children from polluted areas have higher PbU levels than children from less polluted areas. The median levels of cadmium in urine (CdU) are in the order of 0.1 g/g creatinine, with 95th percentiles being in the range of 0.5 and 1.0 g/g creatinine. Girls have higher CdU levels than boys. There are no differences between groups of children from different areas. Children from lead worker families have higher PbU and CdU levels than otherwise comparable children. The results of the present studies indicate a further decrease of PbB in children from North-West Germany since the CEC blood lead campaigns carried out in 1979 and 1981. The decrease of lead exposure also seems to be reflected by a decrease of tooth lead levels.The studies presented in this communication were supported by the Ministry of Work, Health and Social Affairs and the Ministry of Environment and Agriculture of Nordrhein-West-falen, FRG     

Relationship between inhibition of erythrocyte pyrimidine 5′-nucleotidase activity and biological response for porphyrin metabolism in workers occupationally exposed to lead

Summary A rapid determination of erythrocyte pyrimidine 5-nucleotidase (P5N) activity in lead workers was carried out using a high-performance liquid chromatograph (HPLC). The P5N activity had a good negative correlation with the concentration of lead in blood (PbB) ranging from 16 to 96 g/dl (r = -0.82, n = 77). Further, the P5N was compared with other biological parameters: erythrocyte -aminolevulinic acid dehydratase (ALAD) activity, erythrocyte protoporphyrin (PROTO), urinary -aminolevulinic acid (ALA) and urinary coproporphyrin (COPRO).The correlation coefficients between P5N and ALAD, log PROTO, log ALA, and log COPRO were 0.59, –0.72, –0.65, and –0.61, respectively. On the other hand, the normal value of P5N obtained from 72 healthy subjects was 11.9 ± 2.1 units; ol uridine/h/g Hb (mean ± SD), indicating that the lower limit of 95% confidence interval for normal P5N was about 8 units. When P5N was cut off at 8 units in 77 lead workers, the validity (sensitivity + specificity) for PbB 40 g/dl, PbB 60 gg/dl, erythrocyte PROTO 150 g/dl RBC, urinary ALA 6 mg/l, and urinary COPRO 150 g/l was 1.66, 1.76, 1.57, 1.68, and 1.60, respectively. From these results, it was confirmed that the erythrocyte P5N test is suitable for the biological monitoring of exposure to lead in a wide range, and its activity is useful in predicting the disturbance of porphyrin metabolism induced by lead.     

Toxicity of aldicarb and fonofos to the early-life-stage of the fathead minnow

Flow-through early-life-stage (ELS) toxicity tests were conducted with the pesticides aldicarb (Temik^®) and fonofos (Dyfonate^®) to determine their effect on the survival and growth of fathead minnows. Concentrations of 78g/L of aldicarb and 16g/L of fonofos did not affect survival and growth. However, 156g/L of aldicarb and 33g/L of fonofos were lethal to larval-juvenile exposed for 30 days post-hatch. The maximum acceptable toxicant concentration (MATC) of aldicarb and fonofos for the fathead minnow is estimated to be between 78–156g/L and 16–33g/L, respectively. The corresponding chronic values (geometric mean of MATC values) would be 110g/L and 23g/L. Acute toxicity tests gave 96-hr LC50 values of 1370g aldicarb/L and 1090g fonofos/L. The acute-chronic ratio (96-hr LC50/chronic value) is 12 for aldicarb and 47 for fonofos.     

Internal exposure to organic substances in a municipal waste incinerator

Summary Fifty-three persons occupied in a municipal waste incinerator were examined with respect to their internal exposure to organic substances which may be produced during pyrolysis of organic matter. For this purpose the levels of benzene in blood, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in plasma, and mono- (MCPs), di- (DCPs), tri- (TCPs), tetra-(TECPs) and pentachlorophenol (PCP) and hydroxypyrene in urine were determined. For control purposes, 431 men and women were examined. Significantly higher values for the workers were found for the excretion of hydroxypyrene [median (m): 0.24vs 0.11 g/l; non-smokers], 2,4/2,5-DCP (m: 10.5 vs 3.9 g/l) and 2,4,5-TCP (m: 1.2 vs 0.8 g/l) and for the HCB level in plasma (m: 4.4 vs 2.8 g/l). For the concentrations of 4-MCP and 2,3,4,6/2,3,5,6-TECP, the controls had significantly higher concentrations in urine than did the workers in the incineration plant (m: 4-MCP 1.7 vs 1.2; 2,3,4,6/2,3,5,6-TECP: 1.2 vs 0.3 g/l). No significant differences between workers and controls were detected with respect to benzene in blood (m: 0.20 vs 0.28 g/l; non-smokers), 2,4,6-TCP and PCPs in urine (m: 0.85 vs 0.60 and 2.2 vs 2.2 g/l) or the levels of PCB congeners in plasma (m: 138, 153, 180: 5.6 vs 4.1 g/l). The elevated levels of hydroxypyrene, 2,4/2,5-DCP, 2,4,5-TCP and HCB in biological material may be related to the incineration of the waste. These elevations, however, are very small and are of interest more from the environmental than from the occupational point of view.     

Blood styrene concentrations in a “normal” population and in exposed workers 16 hours after the end of the workshift

Summary Blood styrene was measured by a gas chromatography-mass spectrometry method in 81 normal people and in 76 workers exposed to styrene. In the normal subjects, styrene was also tested in alveolar and environmental air. Styrene was found in nearly all (95%) blood samples. Average styrene levels in the normal subjects were 221 ng/1 in blood (Cb), 3 ng/1 in alveolar air (Ca) and 6 ng/1 in environmental air (Ci). Styrene levels did not differ significantly between smokers and non-smokers, 95% of values being below 512 ng/1 in Cb, 7 ng/1 in Ca and 15 ng/l in Ci. In workers with an average exposure to styrene of 204 g/l, at the end of the workshift, mean blood styrene concentration was 1211 g/l. In blood samples collected at the end of the Thursday shift, styrene levels were significantly higher (1590 g/1) than those found at the end of the Monday shift (1068 g/l. A similar difference was found in samples taken the morning after exposure (60 and 119 g/l, respectively). Significant correlations between blood and environmental styrene were found both at the end of the shift and the morning after exposure (r=0.61 and 0.41, respectively). In workers occupationally exposed to styrene, 16 h after the end of the workshift, blood styrene (94 g/l) was significantly higher than that found in the normal subjects (0.22 g/l). The half-life of blood styrene was 3.9 h.     

Toxicity of mercury,copper, nickel,lead, and cobalt to embryos and larvae of zebrafish,Brachydanio rerio

The toxicity of mercury (HgCl₂), copper (CuCl₂: 5 H₂O), nickel (NiSO₄: 6 H₂O), lead (Pb(CH₃COO)₂: 3 H₂O) and cobalt (CoCl₂: 6 H₂O) was studied under standardized conditions in embryos and larvae of the zebrafish,Brachydanio rerio. Exposures were started at the blastula stage (2–4 h after spawning) and the effects on hatching and survival were monitored daily for 16 days. Copper and nickel were more specific inhibitors of hatching than cobalt, lead, and mercury. Nominal no effect concentrations determined from the dose-response relationships (ZEPs, Zero Equivalent Points) for effect on hatching time were 0.05 g Cu/L, 10 g Hg/L, 20 g Pb/L, 40 g Ni/L and 3,840 g Co/L, and those for effect on survival time were 0.25 g Cu/L, 1.2 g Hg/L, 30 g Pb/L, 80 g Ni/L, and 60 g Co/L. The no effect concentrations for Ni, Hg and Pb are consistent with previously reported MATC values for sensitive species of fish. The no effect concentrations for copper are 1–2 orders of magnitude lower than previously reported values. The major reason for the latter discrepancy was considered to be the absence of organics that can complex copper ions in the reconstituted water that we used, which had a hardness of 100 mg/L (as CaCO₃) and a pH of 7.5–7.7. Unexposed controls were started with embryos from different parental zebrafishes and the parental-caused variability in early embryo mortality, median hatching time and median survival time were estimated.     

Behaviour of some indicators of biological effect in female lead workers

Summary The relationships between certain indicators of internal dose and of biological effect were studied in 93 adult women with varying degrees of exposure to lead (PbB levels ranging from 8 to 74 g/ 100 ml). The results were compared with those obtained in a group of 95 males with more of less similar exposure. In both groups a good correlation was found between PbB and ALAD, EP, CPU taken singularly and the trend of the indicators of effect, depending on PbB levels, was similar: the decrease in ALAD values was already clear at PbB levels which do not cause an elevation of EP and the erythrocyte metabolite increased earlier than CPU. Considering the same levels of internal lead load (measured by both PbB and PbU-EDTA) in women, EP values were higher than in the men. No significant difference was established between the two sexes regarding ALAD and CPU values, when considered at the same PbB levels. Validity of ALAD and EP in the females, as already shown in our previous studies on males, was moderate in predicting PbB levels 40 g/100 ml, while it clearly improved at PbB levels 50–60 g/ 100 ml. This indicates that for screening women of child-bearing age the two indicators of effect must be used with caution, since a value of 40 g/100 ml has been proposed as the permissible PbB limit.Abbreviations PbB blood lead (g/100 ml) - PbU-EDTA amount of chelatable lead excreted with 24 hours urine after administration of CaNa₂ EDTA (1 g intravenously) - ALAD -aminolevulinic acid dehydratase activity of erythrocytes (mU/ml RBC) - EP erythrocyte protoporphyrin (g/100 ml RBC) - ALAU urinary -aminolevulinic acid (mg/1) - CPU urinary coproporphyrin (g/1)     

Short-term exposure of zooplankton to the synthetic pyrethroid,fenvalerate, and its effects on rates of filtration and assimilation of the alga,Chlamydomonas reinhardii

In acute tests of toxicity, two cladocerans,Daphnia galeata mendotae andCeriodaphnia lacustris, and the calanoid,Diaptomus oregonensis, were more sensitive to fenvalerate thanDaphnia magna, the organism used in standard laboratory bioassays. The 48-hr EC₅₀s for each species/stage in order of increasing sensitivity were adultD. magna — 2.52 g/L;D. magna (48-hr old) — 0.83 g/L; adultD. galeata mendotae — 0.29 g/L; adultC. lacustris — 0.21 g/L;D. galeata mendotae (48-hr old) — 0.16 g/L; adultDiaptomus oregonensis — –0.12 g/L. No toxicity was observed when these organisms were exposed to a range of concentrations of the emulsifiable concentrate without fenvalerate (the EC blank).Rates of filtration of the¹⁴C-labelled alga,Chlamydomonas reinhardii byD. galeata mendotae, C. lacustris andD. oregonensis were decreased significantly at sublethal concentrations of fenvalerate after only 24-hr exposure.Ceriodaphnia lacustris showed the greatest sensitivity with rates of filtration significantly decreased at 0.01 g fenvalerate/ L. Concentrations of fenvalerate 0.05 g/L resulted in decreased rates of filtration byD. galeata mendotae. A concentration of 0.10 g fenvalerate/ L caused rates of filtration to increase inD. oregonensis. whereas 0.05 and 0.5 g/L resulted in a decrease in these rates.Rates of assimilation of algae byD. galeata mendotae, C. lacustris andD. oregonensis exposed to similar concentrations of fenvalerate were decreased at concentrations 0.05 g fenvalerate/L. Changes in rates of assimilation were not as sensitive a parameter of toxicity as changes in rates of filtration. The EC blank had no significant effects on rates of filtration or assimilation for all three species.     

Peroxidase-catalyzed oxidation of chlorophenols to polychlorinated dibenzo-p-dioxins and dibenzofurans

Chlorophenols are transformedin vitro to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) by peroxidase-catalyzed oxidations. This is demonstrated with bovine lactoperoxidase as well as horseradish peroxidase, and with 3,4,5- and 2,4,5-trichlorophenol (TrCP). The yield of total PCDD/Fs with lactoperoxidase was 11 g per g 345-TrCP and 10 g per g 245-TrCP, of which 2,3,7,8-substituted PCDD/Fs constituted 8.5 and 2.2 g/g, respectively, corresponding to 0.85 and 1.2 g/g of Nordic TCDD-equivalents.     

Biological and environmental monitoring of occupational exposure of pharmaceutical plant workers to methotrexate

Summary The exposure of 11 pharmaceutical plant workers to methotrexate (MTX) was studied. Personal air samples were taken during the different manufacturing processes: drug compounding, vial filling, and tablet preparation. The uptake of MTX was established by the determination of MTX in urine. MTX was analyzed using the fluorescence polarization immunoassay (FPIA), a method that is frequently used for monitoring serum levels in patients treated with MTX. The FPIA method was modified in such a way that MTX could be measured quickly and efficiently in air and urine samples. MTX was detected in air samples of all workers except for those involved in the vial filling process (range: 0.8–182 g/m³; median: 10 g/m³). The highest concentrations were observed for workers weighing MTX (118 and 182 g/m³). MTX was detected in urine samples of all workers. The mean cumulative MTX excretion over 72–96 h was 13.4 g MTX-equivalents (range: 6.1–24 g MTX-equiva g MTX-equivalents (range: 6.1–24 g MTX-equivalents). lents). A significantly lower background level of 10.2 g A significantly lower background level of 10.2 g MTX-equivalents was measured in urine of 30 control persons (range: 4.9–21 g MTX-equivalents).     

Effects of tributyltin on survival,growth, morphometry,and RNA-DNA ratio of larval striped bass,Morone saxatilis

Effects of tributyltin (TBT) on survival, growth, morphometry, and RNA-DNA ratio in larval striped bass(Morone saxatilis) were assessed in three experiments. In Experiment I, 13 day old larvae were exposed to 0, 0.067, 0.766, or 2.284 g TBT/L for 6 days. All larvae exposed to 2.284 /L died by day 5; exposure to 0.766 g/L significantly reduced survival relative to controls (59.8% vs. 81.8%). Significant, concentration-dependent decreases in body depth occurred in larvae exposed to 0.067 and 0.766 g/L. In Experiment II, all 16 day old larvae exposed to 1.498 g/L died by day 6. Survival, weight, and morphometry parameters were not significantly different in larvae exposed to 0, 0.052, or 0.444 g/L for 7 days. In Experiment III, survival was similar in 21 day old larvae exposed to 0, 0.055, 0.218, or 0.514 /L for 7 days. Notochord length and dry weight decreased significantly in larvae exposed to 0.514 g/L. Weight and morphometry parameters were more sensitive indicators of sublethal stress than RNA-DNA ratio. Maximum TBT concentrations reported in Chesapeake Bay marinas are likely to cause increased larval mortality. Longer-term studies are needed to assess effects at <0.050 g/L, which may be more representative of habitat conditions.     

Some hygienic observations from the glass industry

Summary Metallic compounds and other agents used in the manufacturing of glass are probably responsible for the cancer risks observed for glassworkers, especially glassblowers. Few hygienic observations have been reported from the art glass industry. Three glassworks were therefore studied with regard to air concentrations of lead, arsenic, nickel and manganese. The hygienic conditions of the blow-pipes were investigated at these glassworks and another two with regard to inside deposits of slag containing lead, arsenic, manganese and nickel as possible transporters that cause oral exposure. Atomic absorption spectrophotometry was used for the analyses. Apart from lead, the metal concentrations in the air were around the detection limit. Glassworks producing heavy crystal glass usually had higher concentrations of lead in the air than the semi-crystal glassworks. Seven out of 12 samples from heavy crystal glassworks exceeded the Swedish threshold limit of 50 g/m³, while only four out of 28 samples from the semi-crystal glassworks exceeded this limit. Regarding metals in the slag from inside the blow-pipes, the concentrations (geometrical means) of lead and nickel were higher in the heavy crystal glassworks (6.9 g lead/mg slag, and 5.0 g nickel/mg slag versus 0.7 g lead/mg slag and 0.6 g nickel/mg slag in semi-crystal glassworks, respectively). The concentration of arsenic was similarly low in the pipes from all the glassworks ( 0.30 g/mg slag) and the concentration of manganese was only slightly higher in heavy crystal glassworks (5.4 g/mg slag versus 3.6 g/mg slag in semi-crystal glassworks).     

Chronic toxicity and bioaccumulation of 2,5,2′,5′- and 3,4,3′,4′-tetrachlorobiphenyl and Aroclor® 1242 in the amphipodHyalella azteca

The addition of 100 (g/L of Aroclor^® 1242 (A1242) or 2,5,2,5-tetrachlorobiphenyl (TeCB) during 10 week chronic toxicity tests withHyalella azteca resulted in complete mortality. There were no effects on survival, growth, or reproduction after addition of 30 g/L. Toxic effects were observed at tissue levels of between 30 and 180 g/g on a wet weight basis, and tissue levels appear to be a better indicator of toxicity than levels in water. No toxic effects were observed after additions of up to 2,700 g/L of the coplanar congener 3,4,3,4-TeCB.H. azteca has the ability to avoid accumulating in excess of 140 g/g 3,4,3,4-TeCB. The amount taken up was proportional to the amount added in water up to 100 g/L, but was constant at higher additions, possibly accounting for its relatively low toxicity. The low toxicity of the coplanar congener, as compared to the non-coplanar 2,5,2,5-TeCB, is in direct contrast to the high toxicity of coplanar PCB congeners to mammals and may be associated with slower rates of aromatic hydrocarbon metabolism in amphipods. Polychlorinated biphenyl levels measured in amphipods from Lake Ontario are approximately 100-fold below levels associated with toxicity inH. azteca, but are above levels which, through biomagnification up the food chain, lead to salmonid residues in excess of 2 g/g, a tolerance limit for human consumption.     

An effect of erythrocyte protoporphyrin on blood manganese in lead-exposed children and adults

Summary In one study in 2- and 3-year-old children (geom. average 143 g Pb/1) and in two studies in workers (geom. average 483 pg Pb/1 and 323 g Pb/1) manganese in blood levels increased with blood lead and with free erythrocyte porphyrin (FEP). The zero-order correlation between PbB and MnB disappeared when FEP was kept constant. The conclusion is drawn that the increase of MnB with increasing PbB is probably not due to simultaneous exposure, neither to direct interaction between Pb and Mn, but mediated through a relationship between Mn and porphyrin in erythrocytes.This study was supported by a grant from the Dutch Prevention Fund     

Development of a Sublethal Test to Determine the Effects of Copper and Lead on Scleractinian Coral Larvae

A new sublethal toxicity test was developed in this study to measure the effect of copper and lead on the motility of coral larvae. Larval motility was significantly affected by copper and lead doses immediately after dosing. The copper EC₅₀ values for motility of Goniastrea aspera brain coral larvae (12 h, 21 g/L; 24 h, 16 g/L; 48 h, 22 g/L) were much lower than the copper LC₅₀ values for G. aspera larval survival (6 h, 260 g/L, and 24 h, 121 g/L, for 5-day-old larvae and 6 h, 248 g/L, and 24 h, 136.64 g/L, for 6-day-old larvae) during the early part of the experiments. However, at later times, the LC₅₀ values (48 h, 40 g/L, for 5-day-old larvae and 48- h, 87 g/L, for 6-day-old larvae) were similar to the EC₅₀ values for larval motility. The lead 72-h EC₅₀ value for G. aspera larval motility (2900 g/L) was much lower than the lead 72-h LC₅₀ value for larval survival (9890 g/L). The results show that larval motility can be a useful parameter to measure in order to determine the sublethal effects of trace metals on coral larvae.     

The effects of poly chlorinated biphenyls and methylmercury,singly and in combination on mink. II: Reproduction and kit development

Adult ranch-bred mink (Mustela vison) were fed diets containing either 0, 1.0 g/g polychlorinated biphenyls (PCB) (Aroclor^® 1254), 1.0 g/g methylmercury (MeHg), a combination of 1.0 g/g PCB plus 1.0 g/g MeHg, or 0.5 g/g PCB plus 0.5 g/g MeHg. Fertility of adult male mink, percentage of females whelped or number of kits born per female were not affected by the treatments. However, growth rate of kits nursed by mothers exposed to 1.0 g/g PCB was significantly reduced. There was a synergistic effect of PCB and MeHg which reduced kit survival in groups receiving both chemicals simultaneously. Kit survival to weaning in the control, 0.5 g/g PCB/MeHg, and 1.0 g/g PCB/MeHg groups was 72.0%, 62.7% and 35.8%, respectively. The results suggest that growth and survival of mink kits are adversely affected at dietary levels of PCB and MeHg currently present in some environments.     

Increase in the amount of erythrocyte δ-aminolevulinic acid dehydratase in workers with moderate lead exposure

Summary The amount of ALA-D in human erythrocytes was determined directly by radioimmunoassay or calculated from the restored activity assayed in the presence of zinc and dithiothreitol, and a good correlation was observed between the RIA-based and the restored activity-based amounts.The RIA-based amount of ALA-D in the blood of 10 normal individuals (blood lead levels of 5.6 ± 2.3 g/100 ml: mean ± SD) and 19 lead-exposed workers (blood lead levels of 41.2 ± 10.2 g/100 ml) was 54.1 ± 11.8 g/ml blood and 92.3 ± 20.6 g/ml blood, respectively, indicating an apparent increase of the enzyme amount in lead-exposed workers.A significant increase in the amount of erythrocyte ALA-D calculated from the restored activity in lead-exposed workers was observed even in the low blood lead level of 10–20 g/100 ml, resulting in the range of blood lead level 20–40 g/100 ml. No significant difference was observed in hematocrit and hemoglobin content between lead-exposed and non-exposed groups. These observations suggested that the increase of erythrocyte ALA-D in lead exposure was not due to anemia, which might result in the increase of young erythrocytes in peripheral blood.This increase in the amount of ALA-D in human erythrocytes might be a result of the function to overcome the inhibition of the enzyme in bone marrow cells during lead exposure, and these findings may throw light on the danger to human health of low-level lead toxicity.Abbreviations ALA-D -Aminolevulinic acid dehydratase or 5-Amnoevulinic acid hydro-lyase, EC 4.2.1.24 - ALA -Aminolevulinic acid - Rc Reticulocyte - RIA Radioimmunoassay - DTT Dithiothreitol Supported in parts by Science Research Fund of the Ministry of Education, Science and Culture of Japan and by Research Grant of Fujiwara Foundation of Kyoto University     

High medical consultation rates of lead workers after industrial dispute over lead effects

Summary Medical consultation rates were compared between a group of lead workers (346 males) and two groups of non-lead workers (317 and 329 males) in a newspaper company where a serious industrial dispute took place over health effects of lead three years before this study. The comparison was also made within the group of lead workers. Maximal blood lead concentrations (PbBs) ranged from 0.1 mol/kg to 3.6 mol/kg (74 g/ 100 g) with an average of 1.3 mol/kg in the past three years. Ages averaged 35 years in lead workers, and 34 and 30 years in non-lead workers, the ranges being 19-55 years in all.The consultation rate of lead workers was significantly higher than that of both the non-lead workers (P<0.001), when the number of workers who consulted physicians or dentists once or more for a year per 100 workers (general consultation rate) was compared. Disease-specific consultation rates were also higher in lead workers for seven categories of diseases and injuries such as hypertensive disease and peptic ulcers.When lead workers were divided into three groups by PbB or erythrocytes delta-aminolevulinic acid dehydratase (ALAD) levels, however, no significantly high rate was found in the higher PbB groups nor lower ALAD groups in terms of general and disease-specific consultation rates.It was concluded that the industrial dispute might have been a major cause of the high consultation rate of lead workers.     

Toxicity of microencapsulated permethrin to selected nontarget aquatic invertebrates

Microencapsulated permethrin (penncapthrin) was evaluated under laboratory conditions for its toxicity toward several nontarget aquatic invertebrates. Average LC50 estimates for selected lotic invertebrates, based on a one hour dosing regime, were: 2.71 mg/L forSimulium vittatum, 4.59 mg/L forHydropsyche spp., and 13.41 mg/L forIsonychia bicolor. In acute static tests withDaphnia magna, there was no significant difference (p0.05) between the toxicity of penncapthrin at 96 h (LC50 range: 6.80–22.5 g/L) and the EC formulation at 72 h (LC50 range: 0.6–21 g/L). Comparatively, the toxicity of microencapsulated methyl parathion (penncap-m) was not significantly different from that of penncapthrin towardD. magna, the former having LC50 estimates ranging form 0.3–12.25 g/L. LC50 estimates associated withDaphnia pulex ranged from 19 to 131 g/L. The toxicity of penncapthrin and penncap-m towardD. pulex was difficult to determine because of frequent control mortality due to food deprivation resulting from the need to run tests for longer than 48 h. In successful tests, LC50 estimates ranged from 19 to 28 g/L for penncapthrin and 0.08 to 25 g/L for penncap-m after 72 h exposure. In long term toxicity tests, 95% of D. magna at 1 g/L, 44% at 10 g/L, and 20% at 15 g/L survived after 39 days exposure. Less than 15% ofD. pulex survived over the same concentration range following 32 days exposure. Despite some drawbacks, long-term toxicity tests were more appropriate than short-term tests for evaluating microencapsulated sticides because of reduced variability in LC50 estimates and lower control mortality.