Cross-sectional epidemiological study on neurotoxicity of solvents in paints and lacquers

Summary In a multi-disciplinary retrospective study we examined 105 house painters employed for at least ten years (median 27 years, range 10–36 years). Fifty-three workers from various professions (non-painters), who were matched with regard to age, occupational training and socio-economic status served as the control group. In both groups no cases of a clinically manifest polyneuropathy or encephalopathy were found. The neurophysiological examinations (EEG and NCV-measurement) showed no differences in painters and controls that would indicate adverse effects of organic solvents. There were no cases with neuroradiological findings of a diffuse cerebral atrophy. Furthermore the evaluation of certain brain structures (ventricular diameter, cella media index) of the CAT films did not reveal any significant differences. In the neurobehavioral tests significant differences in the results were only found in the subtests change of personality and short term memory capacity in a subgroup of painters with repeated prenarcotic symptoms at the workplace. Ambient air monitoring measurements at 30 representative work-places showed that the concentrations of the main components of the solvent-mixtures were well below the MAK-values. The results of the Erlangen Painter Study does not confirm former epidemiologic findings from other countries, mainly Denmark. However, there are some aspects, such as minor solvent exposure in German house painters, insufficient diagnostic and etiological procedures as well as mis-classifications which may explain the different experiences.     

Reduced exposure to organic solvents by use of water-based paint systems in car repair shops

Objective The objective of this study was to determine to what extent the substitution of solvent-based paint by water-based paint has reduced potential exposure to organic solvents for spray painters in car repair shops.Methods Full-shift personal air sampling (n=79) was carried out over 3 consecutive days in eight car repair shops. Blood samples on the Monday morning (n=26) and at the end of the shift on the Wednesday (n=26), were analysed for organic solvents by headspace techniques.Results Toluene was the organic solvent detected at the highest geometric mean concentration in air samples when solvent-based paint systems were used (0.8 ppm), whereas xylene was found at the highest level when water-based systems were used (0.25 ppm). Toluene, isopropanol, acetone and butyl acetate were detected at higher concentrations when solvent-based paint was used than when water-based paint was employed. The additive factor, based on Norwegian limit values, was three-times higher for the painters using solvent-based paint (0.15) than for those using water-based paint (0.05). On Wednesday after shift the geometric mean of toluene in blood was significantly higher for the painters using solvent-based paint (0.044 g/ml) than for the painters using water-based paint (0.007 g/ml). There was a significant correlation between toluene in personal air samples and toluene in blood samples taken at the end of the shift on the same day.Conclusions When solvent-based paint systems were used the additive factor for organic solvent exposure was three-times higher than when water-based systems were employed. The exposure levels of the organic solvents were well below the Norwegian limit values. The significant correlation between the toluene concentration in air and blood samples indicated that the uptake of organic solvents was correspondingly reduced. At the levels of organic solvents presently described the risk of acute and chronic health effects caused by organic solvents is low.     

Exposure to organic solvents and personality

OBJECTIVES—Although cognitive and neuropsychological changes have been found after high cumulative exposures to solvents, it is not clear whether such exposures are associated with personality characteristics. To study this two groups of British and Chinese dockyard painters who had been heavily exposed to paint solvents have been investigated.
METHODS—260 Male dockyard painters in the United Kingdom, 539 local community controls, 109 Chinese dockyard painters, and 255 dockyard controls completed the Eysenck personality questionnaire, neuroticism (N) and social conformity or dissimulation (L) scales. The non-parametric Kruskal-Wallis test was used to evaluate differences in scores of personality traits between painters and controls. Adjusted relative risks for painters having high N and L scores were calculated in a Breslow-Cox regression analysis, and exposure-response relations were examined in multivariate logistic regression analysis. Non-parametric Spearman's correlation was used to examine relations between previously determined neuropsychological symptoms and personality.
RESULTS—Both British and Chinese data showed that mean neuroticism scores of painters were significantly higher than controls, whereas scores of social conformity did not differ. Relative risk of being a painter increased significantly with increasing N scores, but L scores showed no such trend. In a case-control analysis, there were significant exposure-response relations for the N score. In the United Kingdom the odds ratios (ORs) (95% confidence interval (95% CI), were 2.03 (0.79 to 5.22) for 1-4 years of exposure, 2.38 (0.82 to 6.91) for 5-9 years, 7.05 (1.27 to 39.25) for 10-14 years, and 1.76 (0.63 to 4.89) for 15-41 years. In the Chinese painters, ORs were 4.66 (1.38 to 15.75) for 2-14 years, 10.03 (2.96 to 34.04) for 15-18 years, and 13.56 (3.78 to 48.59) for 19-43 years. Neuroticism was significantly positively related to neuropsychological symptoms in all subjects. Social conformity showed no association with neuropsychological symptoms in British painters and a negative relation among the Chinese painters.
CONCLUSION—Increasing symptoms suggesting neuroticism seemed to relate to the duration of painting whereas scores for social conformity and dissimulation did not. The relation between exposure time and response suggests that increased neuroticism may be caused by long term occupational exposure to organic solvents.


Keywords: organic solvents; painter; dockyards; personality; neuroticism; social conformity     

Blood retinol and β-carotene levels in rural Guatemalan preschool children

Plasma retinol and -carotene levels were measured in 502 preschool Guatemalan children from five rural hamlets. Their ages ranged from 6 to 78 months (mean: 42.9±19.2 months); 45% males and 55% females. The mean retinol value in the whole group was 0.9±0.4 µmol/1 (range: 0.1 to 8.4 µmol/1). There was no significant difference between sexes in retinol mean values nor in the incidence of retinol values less than 0.7 µmol/1 (22% in males, 18% in females). When grouped by age and community, significant low retinol mean values were found in two hamlets in the youngest age group (12 to 23 months) as compared to the other age-groups (p<0.05). In the other two hamlets, there were no significant differences among retinol means by age-group. The highest prevalence of deficient retinol values by age-group was in the 12 to 23 months group (40%), and decreased as age increased. The mean value for -carotene in the whole group was 0.13±0.18 µmol/1 (range: 0.01 to 2.23 µmol/1). There were no significant differences in -carotene means between sexes in the whole group. Stratifying the -carotene data by age-groups and community, values were significantly higher in the 48–59 months and 72–83 months groups, as compared with the other age groups in two of the communities (p<0.05). Significant differences across communities for -carotene were found only in the 12 to 23 months group.     

Risk factors for high blood lead levels among the general populationin Taiwan

Purpose: Environmental and occupational lead pollution is a common problem in both developing and industrialized countries. The purpose of this study is to evaluate the risk factors for high blood lead levels among the general population in Taiwan. Methods: After multi-stage sampling, we randomly selected 2803 subjects (1471 males and 1332 females) for this study. Univariate and multivariate logistic regression analyses were conducted to evaluate the risk of high blood lead. To control for differences in age and gender, all analyses were with age-adjusted and gender-stratified. Results: Among males, the mean age is 46 years (15 to 85 years), mean and median blood lead levels is 7.3 and 6.3g/dl, respectively. Among females, the mean age is 43 years (15 to 84 years), mean and median blood lead level is 5.7 and 4.8g/dl, respectively. Among males, the history of herbal drug use, drinking water from well or spring sources, and occupational lead exposure are significantly different between relatively high and normal blood lead level subjects. The history of occupational lead exposure, history of herbal drug use, and well or spring sources of drinking water are the major risk factors for high blood lead with odds ratio of 4.62 (95% CI: 2.82–7.55), 3.09 (95% CI: 1.60–5.97), 2.06 (95% CI: 1.13–3.76), and 2.37 (95% CI: 1.39–4.04), respectively. Among females, these characteristics remain important except the sources of drinking water. The history of herbal drug use and occupational lead exposure become the major risk factors for high blood lead with odds ratio of 2.94 (95% CI: 1.26–6.88) and 7.72 (95% CI: 3.51–16.99), respectively. In multivariate logistic regression analyses, we find that the risk factors for high blood lead in both genders include a history of herbal drug use and occupational lead exposure. Among males, the drinking water sources and factories in the neighboring areas are also significant factors for high blood lead. Conclusions: For the goal of reducing prevalence of high blood lead by the year 2000, the improvement and monitoring of the working environment, the careful attention to herbal drug use and the lead-free drinking water sources should be executed as thoroughly as possible to reduce the probability of lead pollution.     

Estimated burden of blood lead levels 5 microg/dl in 1999-2002 and declines from 1988 to 1994

In light of recent data suggesting adverse health effects at blood lead levels (PbB) <10 μg/dl, lowering the current definition of elevated blood lead (10 μg/dl) has been recommended. To ascertain the population level impact of such a change, we calculated the prevalence of PbB 5 μg/dl in 1–21-year-old population in the United States. Furthermore, we characterized changes in PbB between 1988–1994 and 1999–2002.We analyzed data from the National Health and Nutrition Examination Survey (NHANES) III (n=10,755) and NHANES 1999–2002 (n=8013).In 1999–2002, about 91.7% of study children had detectable levels of lead in the blood. Among them, 7.3%, 2.8%, and 1.0% children and adolescents aged 1–5, 6–11, and 12–21 years, respectively, had PbB between 5 and 9.9 μg/dl. This number translates to approximately 2.4 million individuals. Between 1988–1994 and 1999–2002, the geometric mean PbB declined from 2.88 to 1.94 μg/dl in children 1–5 years, 1.80 to 1.36 μg/dl in children 6–11 years, and 1.24–1.02 μg/dl in children and adolescents 12–21 years of age. Also, the prevalence of PbB 5 μg/dl declined from 25.7% to 8.8%, 12.8% to 3.0%, and 7.5% to 1.2% in these age groups, respectively.A substantial proportion of children may be at risk for adverse health effects from lead exposure below 10 μg/dl and a large number of children will be classified as having elevated PbB if 5 μg/dl is considered the threshold. Significant public health resources will have to be mobilized for intervention, screening, and case management of these children.     

Higher Body Fat but Similar Phase Angle Values in Patients with the Classical Form of Congenital Adrenal Hyperplasia in Comparison to a Control Group

This study aimed to compare phase angle (PhA) and bioelectrical impedance vector analysis (BIVA) values between adult patients with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency (CAH21OHD) and a control group. A total of 22 patients (15 women, 22.9 ± 3.7 years) were compared with 17 controls (11 women, 27.0 ± 2.5 years). Body composition was determined by dual-energy X-ray absorptiometry. Bioelectrical impedance was used to calculate PhA, and BIVA was performed using specific software. Student’s t-test and analysis of covariance were used to compare groups. Hedges’ G and partial n² were calculated for the effect estimates. Hotelling’s t² test was used to compare the mean impedance vectors between the groups. The Mahalanobis test was used to determine the distance between confidence ellipses. Patients with CAH21OHD had a higher fat mass percentage than that of the control group (both sexes). There was no significant difference in PhA values between groups (CAH21OHD vs. control) in females (6.9° vs. 6.3°, p = 0.092) and males (8.2° vs. 8.1°, p = 0.849), after adjusting for covariates (age and height). BIVA analysis showed a significant difference in the mean impedance vectors between the female groups (T² = 15.9, D = 1.58, p = 0.003) owing to the higher reactance/height (Δ = 8.5; p < 0.001) of the patients. The PhA did not significantly differ between the groups. Female patients had significantly higher reactance values. However, further studies are needed to determine the usefulness of bioimpedance parameters in evaluating the hydration status and cellular integrity of patients with CAH21OHD.     

Lead exposure in indoor firing ranges

Summary Higher air lead levels (time-weighted average 660, range 112–2238 g/m³) were measured in firing ranges where powder charges were employed than in ranges where air guns were used (4.6, range 1.8–7.2 g/m³); levels in the latter were in turn higher than those in ranges used for archery (0.11, range 0.10–0.13 g/m³) Twenty-two marksmen who used powder charges had significantly increased blood lead levels during the indoor shooting season (before: median 106, range 32–176 g/l; after: 138; range 69–288 g/l; P = 0.0001), while 21 subjects who mainly used air guns displayed no significant increase (before: median 91, range 47–179 g/l; after: 84; range 20–222 g/l). Thirteen archers had significantly lower levels than the pistol shooters before the season (P = 0.006), and showed a significant decrease during the season (before: median 61, range 27–92 g/l; after: 56; range 31–87 g/l; P = 0.04). At the end of the indoor season, there was a significant association between weekly pistol shooting time and blood lead levels.     

HAV and HEV infection in hospitalised hepatitis patients in Alexandria, Egypt

A total of 202 serum and stool samples from acute hepatitis patients attending the Fever Hospital of Alexandria, Egypt, have been studied to reveal markers of hepatitis virus infection. Anti-HAV IgM were detected in 21 out of 202 sera (10.4%), whereas 201 sera (99.5%) had anti-HAV IgG. The first age attack was in the class-age 0–9 years with 64.7% of anti-HAV IgM positive sera. Among 202 patients, anti-hepatitis E IgG (sample/over cut off>1.0) was identified in 90 patients (44.5%). The anti-HEV seropositivity ranged from 17.6% to 60.0% in the different age groups, with the highest level in the class-age 20–29 years. Anti-hepatitis E IgM were identified in 49 patients with the first age attack in the class-age 10–19 years (39.4%). HAV RNA was identified by nested PCR in 7 samples out of 15, whereas HEV RNA was present in 4 out of 75 stool samples. Direct DNA sequence of the latter PCR products confirmed the presence of the HEV genome; comparison of the sequences of the isolates from Egypt with those in data banks revealed the highest homology to the Burma strain. Our data confirm that HAV and HEV are common causes of acute sporadic hepatitis in Alexandria but with different peak age positivity. Occasionally, but not infrequently, dual infections (HAV–HEV and HEV-enteric viruses) were also found. The risk analysis indicates that patients living in rural areas are exposed to a higher risk of hepatitis E infection compared to the urban population, whereas the presence of anti-HEV IgG was significantly associated with consumption of common village water and use of indoor dry pit and oral therapy for schistosomiasis.     

Effects of oxygen concentrations on release of mercury from sediments and accumulation byCeratophyllum demersum andAnodonta grandis

The effects of different oxygen concentrations on the release of mercury from sediments and its subsequent accumulation by the plant,Ceratophyllum demersum, and the clam,Anodonta grandis, were investigated. Clams and plants were subjected to three treatments which were designated as control, treatment 1 and treatment 2. Two of the control replicates had normal oxygen concentrations (x=6.4–6.6 mg.L^–1) while the third had reduced concentration (x=1.8 mg.L^–1)- Oxygen concentrations in treatment 1 were reduced (¯x 1.3–2.0 mg.L^–1) for all three replicates. The three replicates in treatment 2 had normal oxygen concentrations (x=6.7–7.2 mg.L^–1). Mercury was added to the sediments in treatments 1 and 2. The resulting measured mean total mercury concentrations ((g.g^–1 dry weight) in the sediments of the replicates were 0.05–0.09 (controls), 4.42–7.28 (treatment 1) and 3.92–5.90 (treatment 2). The mercury concentration in water ranged between 0.10 g.L^–1 to 0.20 g.L^–1 for the six week period that the clams and plants were exposed to one of the three treatments. The total mercury concentrations in water were significantly lower in controls than in treatment 2. In plants, the mercury concentration was significantly higher in deoxygenated treatment 1 as compared to oxygenated treatment 2 and in controls. No significant difference in mercury concentration occurred between control and treatment 2 plants. Clams in treatments 1 and 2 contained significantly more mercury compared to the controls. Mercury concentrations in treatment 1 clams were also significantly higher than in treatment 2 clams. The mercury concentration in water, plants and clams was not significantly different in oxygenated and deoxygenated controls.     

Health effects of solvent exposure among dockyard painters: mortality and neuropsychological symptoms

OBJECTIVES: To study mortality and prevalence of neuropsychological symptoms among a cohort of painters known to have been heavily exposed to organic solvents. METHODS: A mortality study of 1292 male painters who had worked in a dockyard in Scotland for > or = 1 year between 1950 and 1992 comprised a nested cross sectional study of 953 surviving painters from the cohort and 953 male non-painters randomly selected from the local population and a case-control study of those with high symptom scores. Mortality, symptoms, and risks associated with painting, adjusting for age, education, smoking, alcohol, and personality were measured. RESULTS: The proportional mortality ratio for all cancers was not increased significantly (110 (95% confidence interval (95% CI) 84 to 143), except for a possible excess of deaths from ischaemic heart disease (132, 105 to 164). Standardised mortality ratios were not significantly increased. Among the 260 surviving painters and 539 community controls who responded to the questionnaire there was a significant excess of symptoms among painters; adjusted relative risk (RR) increased significantly with increasing symptom score. These RRs suggested an exposure-response relation; for a high score (12-22) for all symptoms RR was 2.27 (1.20 to 4.30) for 1-4 years of exposure, 2.42 (1.18 to 4.95) for 5-9 years, 2.89 (1.42 to 5.88) for 10-14 years, and 3.41 (1.82 to 6.36) for 15-41 years, compared with controls. In multivariate analyses, painting exposure, and aging were associated with high symptom scores and there was again an increased risk relative to time worked as a painter. CONCLUSION: This study supports the hypothesis that heavy and prolonged exposure to paint solvents leads to neuropsychological ill health.

 

     

Lack of oxidative stress in a selenium deficient area in Ivory Coast

Summary Background Previous studies have described an important selenium deficiency in a mountain region (Glanle) in the west of Ivory Coast. Aim of the study To assess the antioxidant capacity of subjects from a selenium deficient area in Ivory Coast (Glanle region). Methods This study involved 57 subjects, 18 to 69 years old, living in the Glanle region and 56 healthy controls living in the southern coastal region (Bodou). In the Glanle region families consume basically a vegetarian and crude palm oil diet, whereas in the Bodou region, families eat a fish–based diet with principally refined palm oil. Fasting blood samples were collected to assess the following parameters: lipid status (plasma total lipids; total–, HDL and LDL–cholesterol; triglycerides; phospholipids; fatty acid composition), plasma protein status (total protein, albumin, transthyretin, orosomucoid, CRP, transferrin), antioxidant capacity (plasma selenium, uric acid, retinol, –tocopherol and tocotrienols levels, plasma seleno–glutathione peroxidase (GSHPx) activity) and oxidative stress markers (malondialdehyde (MDA) and advanced oxidation protein products (AOPP)). Results The mountain region samples (Glanle) were characterized by significantly lower plasma albumin, total–, HDL– and LDL–cholesterol, retinol and selenium levels, plasma PUFA content and GSHPx activity, but significantly higher alpha–tocopherol index and total tocotrienol level, than controls from the coastal area (Bodou). These results suggest a higher exposure risk to oxidative stress for the mountain region subjects. However, the absence of oxidative damage in this group provides evidence of a selenium independent protection mechanism against oxidative stress. This protection is related to lower plasma LDL cholesterol and PUFA content, and to higher –tocopherol index, and total tocotrienols. Conclusion The long–term consumption of crude palm oil could be considered as an effective protective factor against oxidative stress.     

Balance abilities of different-aged workers in physically demanding jobs

The postural and functional balance abilities of workers in physically demanding jobs were assessed in relation to age and occupation. Postural balance was tested with a force platform, and functional balance was measured during walking on a wooden plank. The subjects, 23–61 years of age, were fire fighters (men, n = 69), construction workers (men, n = 52), nursing staff (women, n = 51), and home care workers (women, n = 66). In the older (50 years) groups the time used for the functional balance test was 3–5 s longer and the velocity moment of the postural balance was 16–30 mm²/s higher than in the groups aged 39 years. Construction workers performed better than fire fighters, and both groups had better functional balance than home care workers and nursing staff. The balance demands of work and deterioration with age should be taken into account when work ability is promoted, especially among older workers in physically demanding jobs.     

Age of partners at first intercourse among Danish males and females

In 1984–1985 a representative sample of 286 Danish women (response rate = 75.3%) and 336 Danish men (response rate = 77.8%), ages 16–20 years, was interviewed about their first sexual intercourse. A cumulative frequency function was constructed and the median age at sexual debut was estimated at 16.8 years for both male and female. Generally the age difference between the partners at first intercourse was only a few years. However, the young women almost never reported their first sexual partner as younger than themselves. A cross-check was made of the information given by two homogeneous subsamples of the 47 young women and 80 young men who had their first sexual intercourse with a partner who was also a debutant. Self-reported age among the males differed significantly from the age of the first sexual partner as stated by the females in these subsamples. Therefore, there is bias in the reporting of age of partner at first intercourse. As the self-reported age at first sexual intercourse by young women agrees with the age of first partner as stated by young men, the bias seems to manifest itself predominantly as a systematic misreporting in the age of male partners of debutant females.This work supported by a research grant from Sygekassernes Helsefond.     

The effect of stress on the onset and progression of Creutzfeldt–Jakob disease: Results of a German pilot case–control study

The association between Creutzfeldt–Jakob disease (CJD) and stressful life events was examined in a pilot case–control study in Germany. The study sample consisted of 37 CJD cases and 37 controls, both groups were frequency-matched for age and sex. In standardised interviews of close relatives of the cases and the controls, all stressful life events were assessed and subsequently grouped into one of the following three subgroups: psychosocial stress events, medical operations with hospitalisation, and other serious medical examinations. A significantly higher proportion of CJD cases experienced stressful life events during the last six months before disease onset than controls (65% vs. 32%, p=0.01), yielding an odds ratio (OR) of 3.85 (95% confidence interval (CI): 1.33–11.30). We found the clearest distinction between cases and controls for the subgroup of medical operations where an OR of 6.97 (95% CI: 0.76–329.20) was observed. Further data indicated that stressful events seem to influence not only the onset of CJD but also the progression of the disease. Although based on a rather small study sample, this pilot case–control investigation suggests evidence that stressful life events in the last six months before disease onset may influence CJD occurrence and may modify the course of disease. This stress hypothesis, which is in line with findings from other epidemiological and experimental studies in CJD, is thus a promising direction for future CJD research as it could enlighten the pathophysiological mechanisms and point towards strategies for the prevention and therapy of CJD.     

Time trends in incidence of cervical cancer in Lithuania from 1983 to 1997

This report examines time trends in both age-specific and age-standardized cervical cancer (ICD9-180) incidence rates among Lithuanian women. The study covers the period from 1983 to 1997. In case of the age-specific rates Poisson regression revealed the controversial results for the different age groups. The incidence rates increased ( > 0) for the women below 50 years and decreased ( < 0) for the women above 50 years. The average annual percentage changes were estimated using the age-drift model. In the age groups from 30 to 49 years old the incidence rate increased by 3.3% per year with the 95% confidence interval (CI) being 2.2–4.4. In the age groups from 50 to 69 years old the incidence rate decreased by 2.9% (95% CI: 1.9–3.8). In case of the age-standardized rates during the last few years some increase was observed, although no strict conclusions could be drawn. This observation together with the results of the age-specific rate studies predicts that in the near future the age-standardized rate will start growing.     

Pilot study on prevalence of color vision dysfunction in long-term solvent-exposed painters

Main purpose of our study was to examine whether painters with long-term exposure to mixtures of organic solvents show slight dysfunctions in color vision ability. The study population consisted of 140 men with chronic exposure to organic solvents from paint and thinners (mean duration of exposure: 26 years). We used the Lanthony Desaturated Panel-D-15 (LDP-D15) to test color vision and calculated the color confusion index (CCI). The results were compared with reference values taken from the literature. Additionally the questionnaire Q18 for solvent related neurotoxic symptoms was applied and its results compared with the CCI. Painters between 25 to 55 years old had higher median CCI values than the respective age group of the references. No statistical significant association between CCI and the actual or chronic solvent exposure was found. The results of the Q18 did also not correlate significantly with the exposure indices. We recommend further studies to explore if the color confusion index is an appropriate indicator of early neurotoxic effects in painters.     

Relationship of air lead and blood lead for workers at an automobile battery factory

Summary Air lead and blood lead data, recorded over a period of 3 years for 972 employees at an automobile battery factory as part of a lead control program, were summarized and statistically analyzed. The air lead values were measured by mobile area samplers for approximately 2 years and then by personal samplers for approximately 1 year. Blood lead analyses were usually performed once a month for most of the workers.The trend in air lead levels was significantly upward in the 1st year and significantly downward in the 2nd year while the trend in blood lead levels was significantly downward in the 1st year and in the 3rd year. There were no other significant trends.To assess the relationship between air lead and blood lead, data were used whenever an air lead obtained by personal sampler was followed within 1 month by a blood lead on the same worker. The variables age, job tenure, and department identity were included in an analysis of covariance. Only air lead and departments were significant, accounting for 9% and 13% of the variance in blood lead, respectively. From these data 95% confidence limits were calculated for predicting blood leads from given air leads for an individual worker. These were 30–68 g/100 ml at 200 g/m³; 25–62 g/ 100 ml at 100 g/m³, and 22–60 g/100 ml at 50 g/m³.     

Blood lead concentrations: Apparent reduction over approximately one decade

Summary Blood lead concentrations of male subjects presenting for preemployment examination during the period 1967–1969 have been compared with those obtained during the period 1978–1980. A statistically significant reduction of the geometric mean value from 20.2 g Pb/100 ml whole blood to 16.6 g Pb/100 ml whole blood has been found.