Levels of lead in breast milk and their relation to maternal blood and bone lead levels at one month postpartum

Despite the many well-recognized benefits of breast-feeding for both mothers and infants, detectable levels of lead in breast milk have been documented in population studies of women with no current environmental or occupational exposures. Mobilization of maternal bone lead stores has been suggested as a potential endogenous source of lead in breast milk. We measured lead in breast milk to quantify the relation between maternal blood and bone lead levels and breast-feeding status (exclusive vs. partial) among 310 lactating women in Mexico City, Mexico, at 1 month postpartum. Umbilical cord and maternal blood samples were collected at delivery. Maternal breast milk, blood, and bone lead levels were obtained at 1 month postpartum. Levels of lead in breast milk ranged from 0.21 to 8.02 microg/L (ppb), with a geometric mean (GM) of 1.1 microg/L; blood lead ranged from 1.8 to 29.9 microg/dL (GM = 8.4 microg/dL); bone lead ranged from < 1 to 67.2 microg/g bone mineral (patella) and from < 1 to 76.6 microg/g bone mineral (tibia) at 1 month postpartum. Breast milk lead was significantly correlated with umbilical cord lead [Spearman correlation coefficient (rS) = 0.36, p < 0.0001] and maternal blood lead (rS= 0.38, p < 0.0001) at delivery and with maternal blood lead (rS = 0.42, p < 0.0001) and patella lead (rS= 0.15, p < 0.01) at 1 month postpartum. Mother's age, years living in Mexico City, and use of lead-glazed ceramics, all predictive of cumulative lead exposure, were not significant predictors of breast milk lead levels. Adjusting for parity, daily dietary calcium intake (milligrams), infant weight change (grams), and breast-feeding status (exclusive or partial lactation), the estimated effect of an interquartile range (IQR) increase in blood lead (5.0 microg/dL) was associated with a 33% increase in breast milk lead [95% confidence interval (CI), 24 to 43%], whereas an IQR increase in patella lead (20 microg/g) was associated with a 14% increase in breast milk lead (95% CI, 5 to 25%). An IQR increase in tibia lead (12.0 microg/g) was associated with a 5% increase in breast milk lead (95% CI, -3% to 14%). Our results indicate that even among a population of women with relatively high lifetime exposure to lead, levels of lead in breast milk are low, influenced both by current lead exposure and by redistribution of bone lead accumulated from past environmental exposures.     

Determinants of bone and blood lead levels among minorities living in the Boston area

We measured blood and bone lead levels among minority individuals who live in some of Boston's neighborhoods with high minority representation. Compared with samples of predominantly white subjects we had studied before, the 84 volunteers in this study (33:67 male:female ratio; 31-72 years of age) had similar educational, occupational, and smoking profiles and mean blood, tibia, and patella lead levels (3 microg/dL, 11.9 microg/g, and 14.2 microg/g, respectively) that were also similar. The slopes of the univariate regressions of blood, tibia, and patella lead versus age were 0.10 microg/dL/year (p < 0.001), 0.45 microg/g/year (p < 0.001), and 0.73 microg/g/year (p < 0.001), respectively. Analyses of smoothing curves and regression lines for tibia and patella lead suggested an inflection point at 55 years of age, with slopes for subjects greater than or equal to 55 years of age that were not only steeper than those of younger subjects but also substantially steeper than those observed for individuals > 55 years of age in studies of predominantly white participants. This apparent racial disparity at older ages may be related to differences in historic occupational and/or environmental exposures, or possibly the lower rates of bone turnover that are known to occur in postmenopausal black women. The higher levels of lead accumulation seen in this age group are of concern because such levels have been shown in other studies to predict elevated risks of chronic disease such as hypertension and cognitive dysfunction. Additional research on bone lead levels in minorities and their socioeconomic and racial determinants is needed.     

Lead exposure and amyotrophic lateral sclerosis

BACKGROUND: Previous interview-based studies have suggested that exposure to neurotoxicants including metals might be related to ALS. METHODS: We evaluated the relation of lead exposure to ALS, using both biological measures and interviews, in a case-control study conducted in New England from 1993 to 1996. Cases (N = 109) were recruited at two hospitals in Boston, MA. Population controls (N = 256) identified by random-digit dialing were frequency-matched to cases by age, sex, and region of residence within New England. RESULTS: Risk of ALS was associated with self-reported occupational exposure to lead (odds ratio [OR] = 1.9; 95% confidence interval [CI] = 1.1-3.3), with a dose response for lifetime days of lead exposure. Blood and bone lead levels were measured in most cases (N = 107) and in a subset of controls (N = 41). Risk of ALS was associated with elevations in both blood and bone lead levels. ORs were 1.9 (95% CI = 1.4-2.6) for each microg/dl increase in blood lead, 3.6 (95% CI = 0.6-20.6) for each unit increase in log-transformed patella lead, and 2.3 (95% CI = 0.4-14.5) for each unit increase in log-transformed tibia lead. CONCLUSIONS: These results are consistent with previous reports and suggest a potential role for lead exposure in the etiology of ALS.     

Predictors of plasma lead among lithographic print shop workers in Mexico City

BACKGROUND: Plasma lead is considered a biological marker that reflects the fraction of lead in blood that is toxicologically available. We examined the relationship between plasma lead and other biomarkers of lead exposure in 69 lithographic print shop workers. METHODS: Lead was measured in plasma and whole blood (by inductively coupled plasma-magnetic sector mass spectrometry), in bone (by 109Cd X-ray fluorescence), and in hand wipes and occupational air samples. Personal hygiene habits at work were surveyed. RESULTS: Mean age was 47 years and 86% (n=59) were men. Mean lead levels were 0.3 microg/L in plasma, 11.9 microg/dL in blood, 46.7 microg/g in patella, and 27.6 microg/g in tibia. Taken together, two multivariate linear models explained 57% of variability in plasma lead levels. Predictors for the first model were lead in patella (beta = 0.006), blood (beta = 0.008), and hygiene index (beta = -0.11). Predictors for the second model were lead in tibia (beta = 0.008), blood (beta = 0.008), and hygiene index (beta = -0.13). CONCLUSIONS: This study demonstrates that accumulated bone stores and hygiene habits are both significant independent predictors of plasma lead levels in active workers at this print shop.     

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.     

The delta-aminolevulinic acid dehydratase (ALAD) polymorphism and bone and blood lead levels in community-exposed men: the Normative Aging Study

Recent research has indicated that a polymorphic variant of delta-aminolevulinic acid dehydratase (ALAD) may influence an individual's level of lead in bone and blood and, as a result, may also influence an individual's susceptibility to lead toxicity. In this study, we investigated whether this ALAD polymorphism is associated with altered levels of lead in bone and blood among 726 middle-aged and elderly men who had community (nonoccupational) exposures to lead. We measured levels of blood and bone lead by graphite furnace atomic absorption spectroscopy and a K X-ray fluorescence (KXRF) instrument, respectively. We determined the ALAD MspI polymorphism in exon 4 by a polymerase chain reaction restriction fragment length polymorphism (RFLP). Of the 726 subjects, 7 (1%) and 111 (15%) were, respectively, homozygous and heterozygous for the variant allele. The mean (SD) of blood lead (micrograms per deciliter), cortical bone (tibia) lead (micrograms per gram), and trabecular bone (patella) lead (micrograms per gram) were 6.2 (4.1), 22.1 (13.5), and 31.9 (19.5) in subjects who did not have the variant allele (ALAD 1-1), and 5.7 (4.2), 21.2 (10.9), and 30.4 (17.2) in the combined subjects who were either heterozygous or homozygous for the variant allele (ALAD 1-2 and ALAD 2-2). In multivariate linear regression models that controlled for age, education, smoking, alcohol ingestion, and vitamin D intake, the ALAD 1-1 genotype was associated with cortical bone lead levels that were 2.55 microg/g [95% confidence interval (CI) 0.05-5.05] higher than those of the variant allele carriers. We found no significant differences by genotype with respect to lead levels in trabecular bone or blood. In stratified analyses and a multivariate regression model that tested for interaction, the relationship of trabecular bone lead to blood lead appeared to be significantly modified by ALAD genotype, with variant allele carriers having higher blood lead levels, but only when trabecular bone lead levels exceeded 60 microg/g. These results suggest that the variant ALAD-2 allele modifies lead kinetics possibly by decreasing lead uptake into cortical bone and increasing the mobilization of lead from trabecular bone.     

Lead exposure biomarkers and mini-mental status exam scores in older men

BACKGROUND: Lead is neurotoxic; yet, whether cognitive decline in older persons is associated with lead exposure is unknown. We studied whether lead exposure biomarkers are associated with cognitive test scores, as well as the modifying effects of age on the lead-cognition relationship. METHODS: Lead exposure biomarkers and Mini-Mental Status Exam (MMSE) scores were measured among subjects in the Normative Aging Study. Multiple linear and logistic regression analyses were performed to examine the cross-sectional association of these 2 variables. RESULTS: We found an odds ratio (OR) of 2.1 for MMSE <24 with an increase from the lowest to the highest quartile of patella lead levels (95% confidence interval [CI] = 1.1 to 4.1). From the lowest to the highest quartile of blood lead the OR for low MMSE was 3.4 (CI = 1.6 to 6.2). There was an interaction between lead biomarkers and age. Among subjects in the lowest quartile of patella lead levels, MMSE score decreased by 0.03 points per year (CI = -0.07 to 0.005), whereas in the highest quartile, MMSE score decreased by 0.13 points per year (CI = -0.19 to -0.07). Similar interactions were found between blood lead levels and age. CONCLUSIONS: Increased levels of lead in bone and blood are inversely associated with cognitive performance among older men. Lead exposure might accelerate age-associated cognitive decline.     

Bone lead levels and blood pressure endpoints: a meta-analysis

BACKGROUND: Previous reviews have shown increases in blood pressure and hypertension associated with increases in lead levels in blood. We performed a meta-analysis of the association of bone lead levels with systolic blood pressure, diastolic blood pressure, and hypertension using published data. METHODS: We searched Medline, Embase, and Toxline for epidemiologic studies on bone lead levels and blood pressure endpoints. We used inverse-variance weighted random-effects models to summarize the association of tibia or patella lead levels with blood pressure endpoints. RESULTS: We summarized data from 3 prospective studies and 5 cross-sectional studies. All studies measured lead levels in tibia bone and 3 studies measured lead levels in patella. For a 10 microg/g increase in tibia lead, the cross-sectional summary increases in blood pressure were 0.26 mm Hg for systolic (95% confidence interval = 0.02 to 0.50) and 0.02 mm Hg for diastolic (-0.15 to 0.19). The summary odds ratio for hypertension was 1.04 (1.01 to 1.07). For a 10 microg/g increase in patella lead, the summary odds ratio for hypertension was 1.04 (0.96 to 1.12). CONCLUSION: Systolic blood pressure and hypertension risk were associated with lead levels in tibia bone, but the magnitude of the summary estimates was small. These summary estimates, however, were based on published data and we could not evaluate nonlinear dose-response relationships, the relative contribution of bone and blood lead levels, or the influence of differences in study populations. A more detailed characterization of the association of bone lead levels and blood pressure endpoints would require a pooled analysis of individual participant data from existing studies.     

Prenatal low-level lead exposure and developmental delay of infants at age 6 months (Krakow inner city study)

The purpose of the study was to assess the neurocognitive status of 6-month-old infants whose mothers were exposed to low but varying amounts of lead during pregnancy. Lead levels in the cord blood were used to assess environmental exposure and the Fagan Test of Infant Intelligence (FTII) assessed visual recognition memory (VRM). The cohort consisted of 452 infants of mothers who gave birth to babies at 33-42 weeks of gestation between January 2001 and March 2003. The overall mean lead level in the cord blood was 1.42 microg/dl (95% CI: 1.35-1.48). We found that VRM scores in 6 month olds were inversely related to lead cord blood levels (Spearman correlation coefficient -0.16, p=0.007). The infants scored lower by 1.5 points with an increase by one unit (1 microg/dl) of lead concentration in cord blood. In the lower exposed infants (1.67 microg/dl) the mean Fagan score was 61.0 (95% CI: 60.3-61.7) and that in the higher exposed group (>1.67 microg/dl) was 58.4 (95% CI: 57.3-59.7). The difference of 2.5 points was significant at the p=0.0005 level. The estimated risk of scoring the high-risk group of developmental delay (FTII classification 3) due to higher lead blood levels was two-fold greater (OR=2.33, 95% CI: 1.32-4.11) than for lower lead blood levels after adjusting for potential confounders (gestational age, gender of the child and maternal education). As the risk of the deficit in VRM score (Fagan group 3) in exposed infants attributable to Pb prenatal exposure was about 50%, a large portion of cases with developmental delay could be prevented by reducing maternal blood lead level below 1.67 microg/dl. Although the negative predictive value of the chosen screening criterion (above 1.67 microg/dl) was relatively high (89%) its positive predictive value was too low (22%), so that the screening program based on the chosen cord blood lead criterion was recommended.     

Associations of bone mineral density and lead levels in blood, tibia, and patella in urban-dwelling women

OBJECTIVE: The objective of this study was to evaluate the relations between bone mineral density (BMD) and lead in blood, tibia, and patella and to investigate how BMD modifies these lead biomarkers in older women. DESIGN: In this study, we used cross-sectional analysis. PARTICIPANTS: We studied 112 women, 50-70 years of age, including both whites and African Americans, residing in Baltimore, Maryland. MEASUREMENTS: We measured lumbar spine BMD, blood and bone lead by dual energy X-ray absorptiometry, anodic stripping voltammetry, and (109)Cd-induced K-shell X-ray fluorescence, respectively. We measured vitamin D receptor and apolipoprotein E (APOE) genotypes using standard methods. RESULTS: Mean (+/- SD) BMD and lead levels in blood, tibia, and patella were 1.02+/-0.16 g/cm(2), 3.3+/-2.2 microg/dL, 19.7+/-13.2 microg/g, and 5.7+/-15.3 microg/g, respectively. In adjusted analysis, higher BMD was associated with higher tibia lead levels (p=0.03). BMD was not associated with lead levels in blood or patella. There was evidence of significant effect modification by BMD on relations of physical activity with blood lead levels and by APOE genotype on relations of BMD with tibia lead levels. There was no evidence that BMD modified relations between tibia lead or patella lead and blood lead levels. CONCLUSIONS: We believe that BMD represents the capacity of bone that can store lead, by substitution for calcium, and thus the findings may have relevance for effect-size estimates in persons with higher BMD. RELEVANCE TO CLINICAL PRACTICE: The results have implications for changes in lead kinetics with aging, and thus the related risk of health effects associated with substantial early- and midlife lead exposure in older persons.     

The influence of bone and blood lead on plasma lead levels in environmentally exposed adults.

There is concern that previously accumulated bone lead stores may constitute an internal source of exposure, particularly during periods of increased bone mineral loss (e.g., pregnancy, lactation, and menopause). Furthermore, the contribution of lead mobilized from bone to plasma may not be adequately reflected by whole-blood lead levels. This possibility is especially alarming because plasma is the main circulatory compartment of lead that is available to cross cell membranes and deposit in soft tissues. We studied 26 residents of Mexico City who had no history of occupational lead exposure. Two samples of venous blood were collected from each individual. One sample was analyzed by inductively coupled plasma-magnetic sector mass spectrometry for whole-blood lead levels. The other sample was centrifuged to separate plasma, which was then isolated and analyzed for lead content by the same analytical technique. Bone lead levels in the tibia and patella were determined with a spot-source 109Cd K-X-ray fluorescence instrument. Mean lead concentrations were 0.54 microg/l in plasma, 119 microg/l in whole blood, and 23.27 and 11.71 microg/g bone mineral in the patella and tibia, respectively. The plasma-to-whole-blood lead concentration ratios ranged from 0.27% to 0.70%. Whole-blood lead level was highly correlated with plasma lead level and accounted for 95% of the variability of plasma lead concentrations. Patella and tibia lead levels were also highly correlated with plasma lead levels. The bivariate regression coefficients of patella and tibia on plasma lead were 0.034 (p<0. 001) and 0.053 (p<0.001), respectively. In a multivariate regression model of plasma lead levels that included whole-blood lead, patella lead level remained an independent predictor of plasma lead level (ss = 0.007, p<0.001). Our data suggest that although whole-blood lead levels are highly correlated with plasma lead levels, lead levels in bone (particularly trabecular bone) exert an additional independent influence on plasma lead levels. It will be important to determine whether the degree of this influence increases during times of heightened bone turnover (e.g., pregnancy and lactation).     

Maternal occupational risk factors for oral clefts. Occupational Exposure and Congenital Malformation Working Group

OBJECTIVES: This study investigated the role of maternal exposures at work during pregnancy in the occurrence of oral clefts. METHODS: The occupational exposures of 851 women (100 mothers of babies with oral clefts and 751 mothers of healthy referents) who worked during the first trimester of pregnancy were studied. All the women were part of a multicenter European case-referent study conducted using 6 congenital malformation registers between 1989 and 1992. In each center, the mother's occupational history, obtained from an interview, was reviewed by industrial hygienists who were blinded to the subject's status and who assessed the presence of chemicals and the probability of exposure. Odds ratios (OR) were estimated by a multivariate analysis including maternal occupation or occupational exposures during the first trimester of pregnancy and possible confounding factors such as center of recruitment, maternal age, urbanization, socioeconomic status, and country of origin. RESULTS: After adjustment for confounding factors, cleft palate only was significantly associated with maternal occupation in services such as hairdressing [OR 5.1, 95% confidence interval (95% CI) 1.0-26.0] and housekeeping (OR 2.8, 95% CI 1.1-7.2). The analysis suggests that the following occupational exposures are associated with orofacial clefts: aliphatic aldehydes (OR 2.1, 95% CI 0.8-5.9) and glycol ethers (OR 1.7, 95% CI 0.9-3.3) for cleft lip with or without cleft palate and lead compounds (OR 4.0, 95% CI 1.3-12.2), biocides (OR 2.5, 95% CI 1.0-6.0), antineoplastic drugs (OR 5.0, 95% CI 0.8-34.0), trichloroethylene (OR 6.7, 95% CI 0.9-49.7), and aliphatic acids (OR 6.0, 95% CI 1.5-22.8) for cleft palate only. CONCLUSIONS: Due to the limited number of subjects, these results must be interpreted with caution. However, they point out some chemicals already known or suspected as reproductive toxins.     

Content of lead in human hair from people with various exposure levels in Lithuania

A study has been performed to estimate if hair lead (Pb) can be used assessing environmental and occupational exposure to the metal. From 1994-1997, 622 ceramic plant employees, 520 randomly selected controls from Kaunas without occupational exposure to Pb aged 18-64 years, and 380 10-13 year old children living in Kaunas participated in this study. The concentration of Pb in the hair samples was measured by atomic absorption spectrometry. The geometric mean of Pb in the hair of workers occupationally exposed to Pb was significantly higher than that in persons not exposed to the metal (7.6 microg/g, 95% CI = 6.5-8.7 for exposed workers, 3.2 microg/g, 95% CI = 2.8-3.6 for not exposed workers and 2.6 microg/g, 95% CI = 2.4-2.9 for randomly selected controls, p < 0.05). Pb content in hair of boys and girls was 2.9 microg/g (95% CI = 2.6-3.3) and 3.1 microg/g (95% CI = 2.6-3.6), respectively. Lead in hair was not related to gender. Multiple regression analysis in adults with age as a continuous variable showed a positive relationship between Pb in hair and age. Also different exposure levels were significantly related to Pb in hair. In men, a positive association was found between Pb in hair and smoking. The data obtained suggest that human hair could be used to identify lead exposure in epidemiological surveys.     

Bone, blood and semen lead in men with environmental and moderate occupational exposure

Lead (Pb) in blood, bone, and semen was measured in 162 to 186 environmentally exposed men from Mexico City, aged 19- 48. Semen Pb was measured by inductively coupled plasma mass spectrometry, blood Pb by atomic absorption spectrometry and bone Pb by K X-ray fluorescence. Mean Pb levels in blood, semen, tibia (cortical) and patella (trabecular) bone were 12 microg/dl, 2.7 microg/l, 13 microg/g, and 20 microg/g, respectively. Semen Pb was determined by blood Pb and patella Pb. Determinants of higher tibia Pb were age, living near industry in which Pb is used, and a high occupational Pb exposure index. Higher patella Pb was predicted by age, higher traffic density near home, a high index of occupational exposure to Pb and a greater number of cigarettes smoked per day in the year prior to the study. Blood and bone Pb results are consistent with findings in other populations. Semen results provide new information on the semen-bone Pb relationship. Bone, especially trabecular one, proved to be a significant endogenous lead source for blood and semen burdens in reproductive aged men.     

Proton magnetic resonance spectroscopic evidence of glial effects of cumulative lead exposure in the adult human hippocampus

BACKGROUND: Exposure to lead is known to have adverse effects on cognition in several different populations. Little is known about the underlying structural and functional correlates of such exposure in humans. OBJECTIVES: We assessed the association between cumulative exposure to lead and levels of different brain metabolite ratios in vivo using magnetic resonance spectroscopy (MRS). METHODS: We performed MRS on 15 men selected from the lowest quintile of patella bone lead within the Department of Veterans Affairs' Normative Aging Study (NAS) and 16 from the highest to assess in the hippocampal levels of the metabolites N-acetylaspartate, myoinositol, and choline, each expressed as a ratio with creatine. Bone lead concentrations-indicators of cumulative lead exposure-were previously measured using K-X-ray fluorescence spectroscopy. MRS was performed on the men from 2002 to 2004. RESULTS: A 20-microg/g bone and 15-microg/g bone higher patella and tibia bone lead concentration--the respective interquartile ranges within the whole NAS--were associated with a 0.04 [95% confidence interval (CI), 0.00-0.08; p = 0.04] and 0.04 (95% CI, 0.00-0.08; p = 0.07) higher myoinositol-to-creatine ratio in the hippocampus. After accounting for patella bone lead declines over time, analyses adjusted for age showed that the effect of a 20-microg/g bone higher patella bone lead level doubled (0.09; 95% CI, 0.01-0.17; p = 0.03). CONCLUSIONS: Cumulative lead exposure is associated with an increase in the myinositol-to-creatine ratio. These data suggest that, as assessed with MRS, glial effects may be more sensitive than neuronal effects as an indicator of cumulative exposure to lead in adults.     

Environmental lead level and pregnancy-induced hypertension

Previous studies have suggested that environmental lead exposure increases the risk of hypertension in the general population. In this article, the authors used the 1998 linked birth/infant death database of the United States to examine the association between environmental lead level and the occurrence of pregnancy-induced hypertension (PIH). Yearly summaries of environmental lead levels were abstracted from the US Environmental Protection Agency's air pollution databases, and linked with birth/infant death records by state codes. Generalized estimating equations (GEEs) were used to evaluate the odds ratios of PIH associated with environmental lead measured at ecological levels, with adjustment for maternal age, race, education level, marital status, parity, and adequacy of prenatal care measured at individual levels, stratified by maternal cigarette smoking. A total of 2,994,072 women pregnant in 1998 were included in this study. With the first quartile of lead level as the reference group, the odds ratio for PIH among all study subjects in the second quartile of seasonal average lead level at conception was 1.07 (95% CI: 1.05-1.08), and odds ratios in the third and fourth quartiles were 1.22 (95% CI: 1.20-1.25) and 1.16 (95% CI: 1.15-1.18), respectively. The odds ratios for the second, third, and fourth quartiles of seasonal average lead level at birth were 1.07 (95% CI: 1.05-1.09), 1.21 (95% CI: 1.19-1.23), and 1.15 (95% CI: 1.13-1.17), respectively. The risk of PIH increased by 4% per 0.05 μg/m³ increase in seasonal average lead level at conception and birth, in both smokers and nonsmokers. These results suggest that higher environmental lead levels increase the risk of PIH.     

Occupation as a risk factor for uveal melanoma in Germany

OBJECTIVE: This study explored occupational risks linked to uveal melanoma. METHODS: The analysis pooled data from two case-referent studies (hospital- and population-based) conducted in Germany between 1995 and 1998, with incident cases matched with several referents by age, gender, and region of residence. The subjects were contacted through personal or telephone interviews. Their exposure status was based on their occupational history. Dichotomous coding for the main task and categorization into different occupational classification systems was performed. Altogether of 118 cases and 475 referents were included. Adjusted odds ratios were calculated by conditional logistic regression. RESULTS: Relevant occupations included food, beverage, and tobacco processors [odds ratio (OR) 4.7, 95% confidence interval (95% CI) 0.99-22.0] and miners (OR 2.3, 95% CI 0.92-5.99) among the men and station, engine and heavy equipment operators and freight handlers (OR 2.5, 95% CI 0.94-6.58) and medical, dental, pharmaceutical and veterinary workers (OR 2.1, 95% CI 0.71-6.02) among the women according to the International Standard Classification of Occupations, whereas, according to the European Industrial Classification, the relevant occupations were the food industry (OR 3.4, 95% CI 1.08-10.5) and the chemical and pharmaceutical industry (OR 2.8, 95% CI 1.01-7.78) among the men and machine production (OR 3.2, 95% CI 0.96-10.7) and health and veterinary sector (OR 2.4, 95% CI 0.97-5.71) among the women. CONCLUSIONS: These analyses support the potential role of occupational exposure as a risk factor for uveal melanoma. The findings must be interpreted carefully since the exposure was assessed indirectly.     

Screening housing to prevent lead toxicity in children

OBJECTIVE: Screening children to identify those with blood lead levels > or = 10 microg/dl fails to protect children from lead-associated cognitive deficits and behavioral problems. To broaden our efforts at primary prevention, screening criteria are needed to identify lead-contaminated housing before children are unduly exposed. The purpose of this study was to identify and validate housing characteristics associated with children having elevated blood lead levels (> or = 10 microg/dl). METHODS: Two existing studies were used to examine housing characteristics linked with undue lead exposure: a cross-sectional study of 205 children aged 12 to 31 months, and a random sample from a longitudinal study of 276 children followed from 6 to 24 months of age. Logistic regression analysis was conducted to examine the association of children's blood lead levels > or = 10 microg/dl. RESULTS: The mean age of the 481 children was 17.8 months; 99 (20.6%) had a blood lead concentration of 10 microg/dl or higher. The following characteristics were associated with blood lead concentration > or = 10 microg/dl: floor lead loading > 15 microg/ft2 (odds ratio [OR]=2.2; 95% confidence interval [CI] 1.3, 3.8); rental housing (OR=3.2; 95% CI 1.3, 7.6); poor housing condition (OR=2.1; CI 1.2, 3.6); African American race (OR=3.3; CI 1.9, 6.1); paint chip ingestion (OR=5.8; CI 1.3, 26.5); and soil ingestion (OR=2.2; CI 1.1, 4.2). Housing characteristics including rental status, lead-contaminated floor dust, and housing condition had a range of sensitivity from 47% to 92%; specificity from 28% to 76%; a positive predictive value from 25% to 34%; and a negative predictive value of 85% to 93%. CONCLUSIONS: Housing characteristics and floor dust lead levels can be used to screen housing to identify lead hazards prior to occupancy, before purchasing a home, or after renovation to prevent children's exposure to lead hazards.     

A systematic review of socioeconomic differences in food habits in Europe: consumption of cheese and milk

OBJECTIVE: To assess differences in cheese and milk consumption across socioeconomic groups in representative samples from several European countries. DESIGN: A meta-analysis of published and unpublished surveys of food habits performed in nine European countries between 1985 and 1999. Educational and occupational levels were used as indicators of socio-economic status. RESULTS: A higher socioeconomic status was associated with a greater consumption of cheese. The pooled estimate of the difference in cheese consumption between women in the highest vs the lowest educational level was 9.0 g/day (95% CI: 7.1 to 11.0). The parallel observation in men was 6.8 g/day (95% CI: 3.4 to 10.1). Similar results were obtained using occupation as an indicator of socioeconomic status. The pooled estimates of the higher cheese consumption among subjects belonging to the highest (vs the lowest) occupational level were 5.1 g/day (95% CI: 3.7 to 6.5) in women and 4.6 g/day (95% CI: 2.1 to 7.0) in men. No statistically significant associations were found for milk consumption concerning educational or occupational level. CONCLUSIONS: Our findings suggest that consumption of cheese is likely to be higher among subjects belonging to higher socioeconomic levels. We did not find enough evidence to support that milk intake is different according to educational or social levels.     

Association of tibia lead and blood lead with end-stage renal disease: a pilot study of African-Americans

The association between body lead burden and kidney disease remains controversial. Fifty-five African-American end-stage renal disease (ESRD) cases and 53 age- and sex-matched African-American controls without known renal disease were recruited from Tulane University-affiliated dialysis clinics and out-patient clinics, respectively. Blood lead was measured via atomic absorption spectrophotometry and tibia lead (a measure of body lead) was measured via (109)Cd-based K shell X-ray fluorescence. Median blood lead levels were significantly higher among ESRD cases (6 microg/dL) compared to their control counterparts (3 microg/dL; P<0.001). Although no participants had overt lead poisoning (blood lead > or = 25 microg/dL), seven cases but no controls had blood lead levels above 10 microg/dL (P=0.006). The median tibia lead level was 17 micrograms of lead per gram of bone mineral (microg/g) and 13 microg/g among ESRD cases and their control counterparts, respectively (P=0.134). Four ESRD cases (7%), but no controls, had a tibia lead level above 40 microg/g (P=0.115) while a similar proportion of cases and controls had tibia lead between 20 and 39 microg/g (33% and 32%, respectively; P=0.726). After adjustment for potential confounders, the odds ratios of ESRD associated with a tibia lead > or = 20 microg/g and each four-fold higher tibia lead (e.g., 5-20 microg/g) were 1.55 (95% CI: 0.55, 4.41) and 1.88 (95% CI: 0.53, 6.68), respectively. These findings support the need for prospective cohort studies of body lead burden and renal disease progression.