Examining Links Between Diet and Lead Exposure in Young Children: 2009 to 2014 National Health and Nutrition Examination Survey.

OBJECTIVE: Despite recommendations to consume iron-, calcium-, and vitamin C-rich foods for managing blood lead levels (BLLs), limited evidence exists on how specific foods affect children's BLLs. Using data from 12- to 36-month olds (n = 992) from the 2009 to 2014 National Health and Nutrition Examination Survey, we assessed how foods rich in these nutrients associate with BLLs, and with potential inadvertent exposures to cadmium and mercury. METHODS: Food intake was assessed from one 24-hour dietary recall. Foods were categorized into 10 energy-adjusted groups, with intake categorized as none (reference) and tertiles. BLLs were natural log-transformed. Linear regressions tested associations between food groups and BLLs. Logistic regressions were conducted for blood cadmium and mercury. RESULTS: Median (5%, 95% range) BLLs were 1.01 (0.39, 3.21) µg/dL. Majority of food groups (7 of 10) showed little association with BLLs. Compared to no intake, cereal (tertile 3: ß [95% confidence interval] = -0.22 [-0.41, -0.02]) and milk (Ptrend < 0.002; nonsignificant tertiles) consumption was associated with lower BLLs. Meat (tertile 2: 0.23 [0.01, 0.45]) and fruit drink (tertile 2: 0.20 [0.03, 0.38]; tertile 3: 0.25 [0.02, 0.49]) intake was associated with higher BLLs. Fruit drink consumption was associated with lower likelihood of having blood cadmium >0.11 µg/dL (tertile 3: odds ratio: 0.05 [0.01, 0.36]). No associations were observed with blood mercury. CONCLUSIONS: Among young children, consumption of iron-, calcium-, and vitamin C-rich foods showed weak or no association with BLLs. Few associations were observed for blood cadmium or mercury. Food-based approaches to BLL management may have limited utility when exposure is low.

Association of Low Lead Levels with Behavioral Problems and Executive Function Deficits in Schoolers from Montevideo, Uruguay.

The negative effect of lead exposure on children's intelligence is well-documented. Less is known about the impact of lead on the use of executive functions to self-regulate behavior. We measured blood lead level (BLL) in a sample of first grade children from Montevideo, Uruguay (n = 206, age 6.7 ± 0.5 years, 59.7% boys). Behavior was assessed with teacher versions of the Conners Rating Scale (CRS) and the Behavior Rating Inventory of Executive Functions (BRIEF). Mean BLL was 4.2 ± 2.1 µg/dL; 10% had mild-to-severe ratings of Attentional Deficit with Hyperactivity Disorder (ADHD) (T score > 65). In negative binomial regression, BLL was not associated with CRS sub-scales, but was associated with a poorer ability to inhibit inappropriate behaviors, prevalence ratio (PR) [95% CI]: 1.01 [1.00, 1.03] as measured by the BRIEF. In covariate-adjusted models, the association with BLL was attenuated. When stratified by sex, the covariate-adjusted association between BLL, hyperactivity, poorer inhitibion, emotional control, and behavioral regulation was marginally significant for girls but not boys. In summary, among children with low lead-exposure, we found some, but nonetheless modest, evidence of a relationship between higher BLL and child behavior. If confirmed by larger studies and other objective measures of behavior, such links could have implications for learning and social interaction, particularly among girls.

Lead Exposure in Low and Middle-Income Countries: Perspectives and Lessons on Patterns, Injustices, Economics, and Politics.

Lead exposure is a legacy issue that continues to affect vulnerable population groups globally, but particularly in low and middle-income countries (LMICS). We take a multi-disciplinary approach to examine the patterns of lead exposure in these countries, discuss the underlying injustices and socio-political causes, and the economic costs that are associated with exposure. We conclude with some lessons we drew from our discussion of lead across the disciplines and advocate for a number of approaches to solving this ongoing issue. These include (i) biomonitoring that could be integrated into existing health surveys or public health programs targeting young children; (ii) greater civic engagement to push for solutions; and, (iii) environmental control policies that represent a continuum of local, context-specific to broad, national-level, and even global approaches.

Patterns of PCB exposure among Akwesasne adolescents: The role of dietary and inhalation pathways.

AIM: The objective of this study is to determine if consumption of fish and other dietary elements are related to the serum PCB levels of a group of adolescents. A dietary pattern approach is used to provide a more complete dietary exposure profile rather than a single food/group approach. Additionally, dietary patterns are examined in relation to traditional PCB groupings as well as derived PCB congener profiles. PARTICIPANTS/SETTING AND METHODS: The sample is comprised of 246 Mohawk adolescents between the ages of 10-16.9 years of age residing at the Akwesasne Mohawk Nation. Food frequency data was collected and serum PCB levels were (101 congeners) quantitated during a cross-sectional study investigating adolescent exposure to environmental pollutants. RESULTS: Principal component analysis identified four dietary patterns: "well-rounded" "snacks and sweets" "fruits and vegetables" "fish and dairy" and four PCB congener profiles: "1248-like", Persistent/"1260-like", "mono-ortho", and "1254-like". In a multiple regression models, the "fish and dairy" dietary or traditional PCB determinants (age, sex, prior breastfeeding, BMI, pattern) were each predictors of one or more of three of the identified PCB congener profiles. However, the "1248-like" pattern was not related to either dietary pattern or any of the typical PCB determinants, suggesting an alternative source/exposure pathway for this congener profile. CONCLUSION: Even relatively low levels of fish consumption within the composite dietary matrix of adolescents at Akwesasne remains a pathway of exposure to postnatally acquired PCBs. In addition, there is evidence of an unidentified, perhaps airborne, exposure pathway that warrants further attention as this congener profile accounted for 50% of the total variance within the adolescents' serum PCB levels.

Drinking water lead, iron and zinc concentrations as predictors of blood lead levels and urinary lead excretion in school children from Montevideo, Uruguay.

The global burden of water-based lead (Pb) exposure on children is largely unknown; however, the importance of water sources as a path of Pb exposure is receiving increased attention due to recent prominent exposure events related to corroded plumbing infrastructure in the US. This study investigated the contribution of Pb in household drinking and cooking water to Pb levels in blood (PbB) and urine (PbU) within 353 early school-aged children from Montevideo, Uruguay. Additionally, the analysis considered the child's iron status and the water content of iron (WFe) and zinc (WZn) in relation to water Pb and blood/urine Pb concentrations. Lead concentrations for both PbB and PbU were fairly low (M ±â€¯SD: 4.2 ±â€¯2.1 µg/dL; Median [5%, 95%]: 1.9 [0.6, 5.1 µg/L, respectively]); however 21% of the sample had a PbB >5 µg/dL but ≤ 10 µg/dL. Overall, there was little evidence of an association between water metal concentrations and children's PbB/PbU. However, when the sample was stratified by children's iron status, WPb was positively related to PbU, but negatively related to PbB in iron-replete children, even after adjusting for WFe and WZn. In iron-deficient children, there was no elevation in PbU with increasing WPb. In this sample of children with low Pb levels, there were no overwhelming relationships between WPb and either PbB or PbU, however, there was some evidence that iron-replete status promotes excretion of WPb.

Multiple-metal exposure, diet, and oxidative stress in Uruguayan school children.

Oxidative stress (OS) is an important consequence of exposure to toxic metals but it is unclear to what extent low-level metal exposures contribute to OS in children. We examined the cross-sectional association between urinary concentrations of arsenic (As), cadmium (Cd), and lead (Pb) and urinary markers of OS: F2-8α isoprostane and 8-hydroxy-2-deoxy-guanosine (8-OHdG). We also tested effect modification by dietary intakes. Of the 211 children aged 6-8 years living in Montevideo who were eligible for the study because they had at least one OS marker measured via ELISA, 143 were included in a complete-case analysis. Urinary metals were measured with inductively coupled plasma mass spectrometry (ICP-MS: Pb, Cd) and high-performance liquid chromatography online with hydride generation ICP-MS (As-metabolites); concentrations were log2-transformed. All urinary markers were adjusted for specific gravity of urine. Two 24-h dietary recalls were conducted to estimate children's dietary intakes, including total fruit and vegetable consumption and vitamin C, zinc and fiber intake. Ordinary least square (OLS) and weighted quantile sum (WQS) regressions were used to estimate the association between metals and each OS marker as outcome. Metal exposure was generally low: median urinary As, Cd, Pb 9.6 µg/L, 0.06 µg/L and 1.9 µg/L, respectively. Median 8-isoprostane concentration was 1.1 and 8-OHdG 39.6 ng/mL. Log2-transformed urinary As concentrations were positively associated with 8-OHdG concentrations (10.90 [3.82, 17.97]) in covariate-adjusted OLS models which also took account of exposure to Cd and Pb. In WQS, a mixture index was also associated with higher 8-OHdG (8.71 [1.12, 16.3] for each 25% increase in index value), mostly driven by As exposure. There was little evidence of effect modification by dietary antioxidants. In sum, even at low-level, As exposure is associated with detectable oxidative damage to the DNA.

Persistent organic pollutants as predictors of increased FSH:LH ratio in naturally cycling, reproductive age women.

Although several recent studies suggest endocrine disrupting compounds, such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p', DDE), and hexachlorobenzene (HCB), target different organs and systems in the body, their impact on female reproductive function in humans is not well characterized. We seek to determine the relationship between several known endocrine disrupting compounds and a marker of ovarian responsivity, the FSH:LH ratio (higher ratio indicates less ovarian responsivity). For this analysis, 169 naturally cycling women between 21 and 38 years of age completed interviews and had their blood drawn on day 3 of their menstrual cycle for analyses of toxicants, gonadal sex hormones (E2 and P4), and gonadotropins (FSH and LH). PCB congeners were classified into five groups based on their environmental persistence, distribution in human tissue, and toxicological action, reflecting the structure, mechanism, and known biological activity of individual PCB congeners. For every unit (ppb) increase in the level of the estrogenic PCB group, there was a 5-fold greater risk of a FSH:LH ratio ≥ 2, controlling for individual differences in age, percent body fat, cycle day 3 estradiol levels, parity, alcohol use and cigarette smoking in the past year (exp[ß] = 5; p = ≤0.01). PCB congeners identified as estrogenic were analyzed individually, and, of the 19 potentially estrogenic congeners, five were significantly, and positively related to an increased FSH:LH ratio. Four of these congeners are non-persistent, easily volatilize in the environment, and are easily metabolized, and hence, are indicative of very recent or current exposure. p,p'-DDE and HCB were not associated with FSH:LH ratio. We find a clinical indicator of ovarian responsivity, FSH:LH ratio, is associated with a specific group of estrogenic PCBs. These congeners may become airborne when they volatilize from dredged PCB-contaminated soil or from indoor PCB-containing window caulk and sealants in older buildings leading to inhalation exposure. PCB exposure, particularly to non-persistent, estrogenic congeners, may pose an unrecognized threat to female fecundity within the general population.

Endocrine disrupting chemicals and ovulation: Is there a relationship?

Although the potential for endocrine disrupting chemicals (EDCs) to disrupt female fecundity is great, few studies have assessed the threat to human reproduction. This study investigates levels of organochlorines in relation to their impact on women's menstrual cycles and ovulatory status. To address concerns of the Akwesasne Mohawk community in upstate New York regarding well-established exposure to EDCs, women's fertility and reproductive health endpoints, we recruited 215 women between the ages of 21 and 38 years to measure menstrual cycle characteristics and levels of local pollutants. Of these, 155 women collected saliva over the course of their menstrual cycle allowing for analysis of estradiol and progesterone levels and the determination of ovulatory status in relationship to their serum pollutant levels. A subset of participants (15) who did not commence cycling within a month of their enrollment were not included in the analysis, hence reducing the sample size to 140 participants. Additionally, a lipid panel, estradiol and progesterone were assessed in serum on Day 3 of the menstrual cycle. Median cycle length for women in the sample was 29 days. After aligning the cycles, 110 women were considered ovulatory and 45 (29%) anovulatory. Concentrations of groups of more persistent PCBs congeners, HCB, and p,p'-DDE did not differ significantly with ovulatory status. However, a sub-group of low-chlorinated PCB congeners, considered to be estrogenic were significantly higher among anovulatory women. These findings suggest that certain EDC's, ubiquitous in our environment, may adversely affect menstrual cycles and thus have the capacity to impair reproductive function, including likelihood of conception.

Applying the community partnership approach to human biology research.

Contemporary human biology research employs a unique skillset for biocultural analysis. This skillset is highly appropriate for the study of health disparities because disparities result from the interaction of social and biological factors over one or more generations. Health disparities research almost always involves disadvantaged communities owing to the relationship between social position and health in stratified societies. Successful research with disadvantaged communities involves a specific approach, the community partnership model, which creates a relationship beneficial for researcher and community. Paramount is the need for trust between partners. With trust established, partners share research goals, agree on research methods and produce results of interest and importance to all partners. Results are shared with the community as they are developed; community partners also provide input on analyses and interpretation of findings. This article describes a partnership-based, 20 year relationship between community members of the Akwesasne Mohawk Nation and researchers at the University at Albany. As with many communities facing health disparity issues, research with Native Americans and indigenous peoples generally is inherently politicized. For Akwesasne, the contamination of their lands and waters is an environmental justice issue in which the community has faced unequal exposure to, and harm by environmental toxicants. As human biologists engage in more partnership-type research, it is important to understand the long term goals of the community and what is at stake so the research circle can be closed and 'helicopter' style research avoided.

Dietary patterns of Akwesasne Mohawk adolescents.

BACKGROUND: Native American youth have greater rates of overweight/obesity than same-aged youth from the general population. Even though dietary shifts are suspected, surprisingly little information exists concerning the dietary patterns of contemporary Native American adolescents. AIM: This study examines the dietary composition of Native American adolescents residing in upstate New York at the Akwesasne Mohawk Nation. The goal of this investigation is to assess the food patterns of Akwesasne adolescents via a total diet approach. PARTICIPANTS/SETTING AND METHODS: The sample is comprised of 246 Mohawk adolescents between the ages of 10-16.9 years of age residing at the Akwesasne Mohawk Nation. Food frequency data was collected from adolescents via interview during a cross-sectional study investigating their exposure to environmental pollutants. RESULTS AND CONCLUSION: Nutrient-dilute but energy-dense foods characterize most of the top 10 dietary sources of energy, carbohydrates, and fat. Although micronutrient intakes are by and large adequate in the sample, micronutrients are most often derived from highly fortified food sources. Adolescent diets contain few naturally-occurring sources of many micronutrients, especially folate and iron. A narrow variety of foods dominate the top dietary sources across both macronutrient and micronutrients, strongly suggesting the need for increased dietary diversity within this age group.

Environmental influences on human growth and development: historical review and case study of contemporary influences.

Over the past 100 years, the study of environmental influences on human physical growth and development has focused on the influences of social and economic factors; family and household characteristics; urbanization/modernization; nutrition; and features of the physical environment such as altitude, temperature and climate. Continuing in this tradition are current investigations into the roles of pollutants and other aspects of the human-made environment in affecting patterns of human growth and development, specifically the timing of sexual maturation and the development of obesity. Some of the methodological problems in conducting such studies are presented, as are results from an ongoing investigation among one Native American community that show relationships of pollutants to sexual maturation, overweight/obesity and thyroid system function which can impact growth and maturation.

Persistent organic pollutants and anti-thyroid peroxidase levels in Akwesasne Mohawk young adults.

Persistent organic pollutants, such as polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and p,p'-dichlorophenyldichloroethylene (DDE), have been found to elicit a broad spectrum of biologic, metabolic, and immunologic responses. The potential of these pollutants to impair immune responses and trigger autoimmune disease is of growing concern, given their structural similarity to thyroid hormones and their potential to modulate the mechanisms and interfere with the binding of these hormones. We examine the relationship of different groupings of PCBs, according to chlorination and structure, and of p,p'-DDE and HCB to anti-thyroid peroxidase antibody, a useful tool in the evaluation of thyroid dysfunction, among 115 young adults of the Akwesasne Mohawk Nation. Overall, 18 participants (15.4%) had anti-thyroid peroxidase antibodies (TPOAb) levels above the normal laboratory reference range (23% of females, 9% of males). Among participants who were breast fed (n=47), those with an elevated TPOAb level had significantly higher levels of all PCB groupings, with the exception of levels of non-persistent PCBs which did not differ significantly. Levels of p,p'-DDE were also significantly elevated, while HCB and mirex were not higher among those with elevated TPOAb. Also, after stratifying by breast-feeding status, participants who were breast fed showed significant, positive relationships between TPOAb levels and all PCB groupings, except groups comprised of non-persistent PCBs, and with p,p'-DDE, HCB, and mirex. No effects were evident among non-breast-fed young adults. Further studies are necessary to elucidate the site and mechanism of action of these persistent organic pollutants (POPs) and to establish thresholds for these effects, especially among populations with background levels of toxicant exposure.

Relationship of thyroid hormone levels to levels of polychlorinated biphenyls, lead, p,p'- DDE, and other toxicants in Akwesasne Mohawk youth.

BACKGROUND: It is well documented that acute exposure to high levels of persistent organic pollutants, such as polychlorinated biphenyls (PCBs), p,p'-dichlorophenyldichloroethylene (p,p'-DDE), and hexachlorobenzene (HCB), can affect human health including thyroid function. Chronic exposure to multiple toxicants is common but difficult to analyze, and most prior studies have focused on adults or newborns, creating a gap in our understanding of multitoxicant effects among adolescents. OBJECTIVE: We investigated whether levels of PCBs, p,p'-DDE, HCB, mirex, lead, and mercury reflecting past chronic exposure are associated with alterations in levels of thyroid-stimulating hormone (TSH), triiodothyronine (T(3)), total thyroxine (TT(4)), and free thyroxine (FT(4)) among older children and adolescents. METHODS: The sample consists of youth from the Akwesasne Mohawk Nation (n=232) who reside in proximity to several industries that have contaminated the local environment. We used multiple regression analysis to examine the effect of PCB groupings, p,p'-DDE, HCB, lead, and mercury on thyroid hormones after adjusting for sociodemographic covariates and controlling for all other toxicants. RESULTS: Exposure to PCBs affects the thyroid hormone profile in adolescents. The group of persistent PCBs was positively associated with TSH but inversely related to FT(4). Nonpersistent PCBs were significantly and negatively related to FT(4) only. HCB was negatively associated with T(4), and lead was positively associated with T(3). Breast-fed adolescents had higher levels of persistent PCBs and p,p'-DDE but not of nonpersistent PCBs or any other toxicant when compared with non-breast-fed adolescents. Though having lower levels of persistent PCBs and p,p'-DDE, non-breast-fed adolescents exhibited significant relationships between persistent PCBs and TSH and FT(4), but breast-fed adolescents did not. It appears that PCBs from breast milk obscure the relationship between prenatal PCB exposure and thyroid function by adding random variation in PCB levels. CONCLUSION: Our results demonstrate a reduction in thyroid function in adolescents in relation to their current serum levels of PCBs. These observations are consistent with the hypothesis that pre-natal exposure to PCBs alters thyroid function in a long-lasting manner but does not exclude the possibility that postnatal exposure is influential also.

Advancing biocultural models by working with communities: a partnership approach.

Culture and human behavior are recognized today as major forces acting on human biological variation around the world. Studies of the relationships between biology and processes, such as modernization, urbanization, and social stratification, are prominent in our journals and meetings. An ongoing study of the interrelationships between toxicant exposure (organochlorines, lead, and mercury), health, and culture among youth of the Mohawk Nation at Akwesasne is located within this context and is used to analyze the strengths and challenges of a partnership approach to biocultural research. To assist in modeling the complex relationships between health, behavior, and culture, we have employed concepts from contemporary social theory, integrated qualitative and quantitative research, and implemented community-based research principles to develop a partnership approach to research in human biology. The community is directly involved in identifying research goals, developing research protocols appropriate for local cultural sensitivities and complexities, implementing the protocols in the field, and collaborating in the analysis and publication of results. We show the utility of this approach for understanding the relationships of toxicants to behavior and biological outcomes (adolescent growth, sexual maturation, and endocrine system alteration); as well as how it facilitates the agency of participants and communities involved in research, and brings greater social engagement to the development of the new human biology.

PCBs and cognitive functioning of Mohawk adolescents.

This paper reports on the relationships between the cognitive functioning and PCB current body burdens of adolescents in the Mohawk Nation of Akwesasne where there is concern about industrial pollution of the environment. Three cognitive tests (Woodcock Johnson-Revised, Test of Memory and Learning, and Ravens Progressive Matrices) provide 13 subtests that allow a variety of cognitive outcomes to be assessed. A summary measure of PCB level was created from the congeners detected in at least 50% of the participants. The most notable finding was the significant negative relationship between PCB levels and two separate measures of long term memory. There was also a negative relationship with a measure of comprehension and knowledge. Significant relationships were not large, but provide evidence of subtle negative effects of PCB exposure.

Effects of pollution on human growth and development: an introduction.

Pollution is a worldwide problem and its potential to influence the physiology of human populations is great. Studies of human growth and development in relation to pollution have increased in number and quality since the mid-twentieth century. Many studies have found that some pollutants have detrimental effects on human growth, particularly prenatal growth. The heavy metal, lead, is commonly found in human populations and is related to smaller size at birth and studies have reported decrements that range up to about 200 grams. Noise stress from transportation sources also is related to reduced prenatal growth with somewhat smaller decrements reported. Studies of humans exposed to polychlorinated biphenyls, one of the persistent organic pollutants, have reduced size at birth, advanced sexual maturation and altered hormone levels related to thyroid regulation. Thus different pollutants exert effects through different physiological pathways. However, some studies have not observed these effects, which indicates that the situation is complex and requires further study with better study designs. Determining the effects of pollutants on human physiology and growth is difficult as it requires fairly large numbers of subjects who are not purposely exposed but for whom exposure can be measured. These effects of pollutants and the mechanisms of effect require further study to understand and, it is hoped, to blunt or block any detrimental effects on human health and well-being.

Health disparities and toxicant exposure of Akwesasne Mohawk young adults: a partnership approach to research.

In this article we describe a research partnership between the Akwesasne Mohawk Nation and scientists at the University at Albany, State University of New York, initiated to address community and scientific concerns regarding environmental contamination and its health consequences (thyroid hormone function, social adjustment, and school functioning). The investigation focuses on cultural inputs into health disparities. It employs a risk-focusing model of biocultural interaction: behaviors expressing cultural identity and values allocate or focus risk, in this instance the risk of toxicant exposure, which alters health status through the effects of toxicants. As culturally based behaviors and activities fulfill a key role in the model, accurate assessment of subtle cultural and behavioral variables is required and best accomplished through integration of local expert knowledge from the community. As a partnership project, the investigation recognizes the cultural and socioeconomic impacts of research in small communities beyond the production of scientific knowledge. The components of sustainable partnerships are discussed, including strategies that helped promote equity between the partners such as hiring community members as key personnel, integrating local expertise into research design, and developing a local Community Outreach and Education Program. Although challenges arose during the design and implementation of the research project, a collaborative approach has benefited the community and facilitated research.

Relationship of lead, mercury, mirex, dichlorodiphenyldichloroethylene, hexachlorobenzene, and polychlorinated biphenyls to timing of menarche among Akwesasne Mohawk girls.

BACKGROUND: Children are commonly exposed at background levels to several ubiquitous environmental pollutants, such as lead and persistent organic pollutants, that have been linked to neurologic and endocrine effects. These effects have prompted concern about alterations in human reproductive development. Few studies have examined the effects of these toxicants on human sexual maturation at levels commonly found in the general population, and none has been able to examine multiple toxicant exposures. The aim of the current investigation was to examine the relationship between attainment of menarche and levels of 6 environmental pollutants to which children are commonly exposed at low levels, ie, dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), mirex, lead, and mercury. METHODS: This study was conducted with residents of the Akwesasne Mohawk Nation, a sovereign territory that spans the St Lawrence River and the boundaries of New York State and Ontario and Quebec, Canada. Since the 1950s, the St Lawrence River has been a site of substantial industrial development, and the Nation is currently adjacent to a US National Priority Superfund site. PCB, p,p'-DDE, HCB, and mirex levels exceeding the US Food and Drug Administration recommended tolerance limits for human consumption have been found in local animal species. The present analysis included 138 Akwesasne Mohawk Nation girls 10 to 16.9 years of age. Blood samples and sociodemographic data were collected by Akwesasne community members, without prior knowledge of participants' exposure status. Attainment of menses (menarche) was assessed as present or absent at the time of the interview. Congener-specific PCB analysis was available, and all 16 PCB congeners detected in >50% of the sample were included in analyses (International Union of Pure and Applied Chemistry numbers 52, 70, 74, 84, 87, 95, 99, 101 [+90], 105, 110, 118, 138 [+163 and 164], 149 [+123], 153, 180, and 187). Probit analysis was used to determine the median age at menarche for the sample. Binary logistic regression analysis was used to determine predictors of menarcheal status. Six toxicants (p,p'-DDE, HCB, PCBs, mirex, lead, and mercury) were entered into the logistic regression model. Age, socioeconomic status (SES), and BMI were tested as potential cofounders and were included in the model at P < .05. Interactions among toxicants were also evaluated. RESULTS: Toxicant levels were measured in blood for this sample and were consistent with long-term exposure to a variety of toxicants in multiple media. Mercury levels were at or below background levels, all lead levels were well below the Centers for Disease Control and Prevention action limit of 10 microg/dL, and PCB levels were consistent with a cumulative, continuing exposure pattern. The median age at menarche for the total sample was 12.2 years. The predicted age at menarche for girls with lead levels above the median (1.2 microg/dL) was 10.5 months later than that for girls with lead levels below the median. In the logistic regression analysis, age was the strongest predictor of menarcheal status and SES was also a significant predictor but BMI was not. The logistic regression analysis that corrected for age, SES, and other pollutants (p,p'-DDE, HCB, mirex, and mercury) indicated that, at their respective geometric means, lead (geometric mean: 0.49 microg/dL) was associated with a significantly lower probability of having reached menarche (beta = -1.29) and a group of 4 potentially estrogenic PCB congeners (E-PCB) (geometric mean: 0.12 ppb; International Union of Pure and Applied Chemistry numbers 52, 70, 101 [+90], and 187) was associated with a significantly greater probability of having reached menarche (beta = 2.13). Predicted probabilities at different levels of lead and PCBs were calculated on the basis of the logistic regression model. At the respective means of all toxicants and SES, 69% of 12-year-old girls were predicted to have reached menarche. However, at the 75th percentile of lead levels, only 10% of 12-year-old Mohawk girls were predicted to have reached menarche; at the 75th percentile of E-PCB levels, 86% of 12-year-old Mohawk girls were predicted to have reached menarche. No association was observed between mirex, p,p'-DDE, or HCB and menarcheal status. Although BMI was not a significant predictor, we tested BMI in the logistic regression model; it had little effect on the relationships between menarcheal status and either lead or E-PCB. In models testing toxicant interactions, age, SES, lead levels, and PCB levels continued to be significant predictors of menarcheal status. When each toxicant was tested in a logistic regression model correcting only for age and SES, we observed little change in the effects of lead or E-PCB on menarcheal status. CONCLUSIONS: The analysis of multichemical exposure among Akwesasne Mohawk Nation adolescent girls suggests that the attainment of menarche may be sensitive to relatively low levels of lead and certain PCB congeners. This study is distinguished by the ability to test many toxicants simultaneously and thus to exclude effects from unmeasured but coexisting exposures. By testing several PCB congener groupings, we were able to determine that specifically a group of potentially estrogenic PCB congeners affected the odds of reaching menarche. The lead and PCB findings are consistent with the literature and are biologically plausible. The sample size, cross-sectional study design, and possible occurrence of confounders beyond those tested suggest that results should be interpreted cautiously. Additional investigation to determine whether such low toxicant levels may affect reproduction and disorders of the reproductive system is warranted.

Relationship between blood lead concentration and dietary intakes of infants from 3 to 12 months of age.

Data from a study of mother-infant pairs of low socioeconomic status living in Albany County, NY, were analyzed to determine the influence of diet and nutrition on the blood lead level of infants during the first year of life. Children's diets were assessed at 3-month intervals using a 24-h diet recall as reported by the primary caregiver. The potential impact of dietary consumption of protein, iron, zinc, calcium, vitamin D, and fat, as well as serum vitamin D and ferritin on blood lead levels at 6 and 12 months of age was examined with multivariable statistical analyses, controlling for other influences on lead levels. Neonates' blood lead levels were low at birth (geometric mean=1.6 microg/dL), and none were elevated (> or = 10 microg/dL). By 12 months, the mean blood lead for this sample was 5.1 microg/dL, and 18% of the sample had an elevated blood lead level. We observed significant inverse relationships between infants' 6-month lead level and their intake of zinc, iron, and calcium. At 12 months, low iron intake continued to be associated with higher lead levels, although zinc and calcium did not. Protein had a paradoxical effect, being associated with lower lead at 6 months, but higher lead at 12 months. Serum vitamin D and ferritin were not associated with lead levels, nor was vitamin supplement use. The results reported here emphasize the value of key minerals in the diet to reduce lead absorption during early infancy.