The association between cadmium, lead and mercury blood levels and reproductive hormones among healthy, premenopausal women

Mercury, natural fertility and outcomes of assisted reproduction: A systematic review

The primary route of mercury exposure for the general population is through consumption of contaminated seafood. There is a biological basis for an adverse effect of mercury exposure on human fertility. The goal of this review was to evaluate the existing literature on the association between mercury and pregnancy, among men and women attempting to conceive with and without assisted reproductive technology (ART). Systematic searches were performed in PubMed, EMBASE, Scopus and Web of Science for papers published up to March 2023 with no early date restriction, only including studies with a biomarker measurement of mercury exposure. We identified 11 studies examining mercury and natural fertility and 12 studies examining mercury and outcomes of assisted reproduction (implantation or clinical pregnancy). The accumulated evidence provides some support for a null association between bodily mercury concentrations and natural fertility among women, however, a large proportion of studies did not report adjusted estimates or were extremely imprecise. The majority of studies of natural fertility were also cross-sectional in nature. There was no evidence for an inverse or null association between mercury and natural fertility among men, or mercury and ART outcomes among men or women. In spite of biological plausibility, the existing evidence includes studies that are imprecise and often conflicting and does not allow us to make definitive conclusions on the associations of mercury exposure with successful pregnancy. Additional, larger studies are warranted, especially among individuals with high concentrations of mercury exposure as these individuals may be underrepresented in the current literature.

Association between blood lead levels and parathyroid hormone among United States adolescents aged 12-19: a cross-sectional study

Aims

Studies on the association between serum lead levels and parathyroid function in adolescents are lacking. Therefore, in this study, we elucidated the possible association between blood lead levels (BLLs) and the parathyroid hormone (PTH) in adolescents aged 12-19 years in the United States.

Methods

In this study, information from the database of the National Health and Nutrition Examination Survey was utilized. The study included 3919 participants from survey cycles between 2003-2004 and 2005-2006. Multivariable linear regression analysis was performed to determine the correlation between BLLs and PTH. Furthermore, smooth curve fitting was utilized to analyze the dose-response relationship between BLLs and PTH.

Results

Multivariable linear regression analysis revealed that every 1 μg/dL increase in BLLs was associated with 0.67 pg/mL increase in PTH (β = 0.67, 95% CI: 0.16-1.18, p < 0.01). However, sex-stratified subgroup analysis revealed that this positive association was only observed in males (β = 1.16, 95% CI: 0.50-1.83 p < 0.01). Smooth curve fitting revealed a positive correlation between BLLs and PTH.

Conclusions

In adolescents in the United States, BLLs are positively correlated with PTH, particularly in males.

Cadmium as an ovarian toxicant: A review

Cadmium (Cd) is a ubiquitous heavy metal toxicant with no biological function in the human body. Considerably, because of its long biological half-life and very low excretion rate, Cd is inclined to accumulate and cause deleterious effects on various body organs (e.g., liver, kidney, and ovary) in humans and animals. Ovaries are the most vulnerable targets of Cd toxicity. Cd has been shown to induce oxidative stress, follicular atresia, hormonal imbalance, and impairment of oocyte growth and development. Moreover, Cd toxicity has been associated with increasing incidences of menstrual disorders, pregnancy loss, preterm births, delayed puberty, and female infertility. Therefore, it is crucial to understand how Cd poisoning impacts specific ovarian processes for the development of preventive interventions to enhance female fertility. The current review attempts to collate the recent findings on Cd-induced oxidative stress, follicular apoptosis, steroid synthesis inhibition, and teratogenic toxicity, along with their possible mechanisms in the ovarian tissue of different animal species. Additionally, the review also summarizes the studies related to the use of many antioxidants, medicinal herbs, and other compounds as remedial approaches for managing Cd-induced ovarian toxicity.

Correlates of whole blood metal concentrations among reproductive-aged Black women

BACKGROUND

Metals may influence reproductive health, but few studies have investigated correlates of metal body burden among reproductive-aged women outside of pregnancy. Furthermore, while there is evidence of racial disparities in exposure to metals among U.S. women, there is limited research about correlates of metal body burden among Black women.

OBJECTIVE

To identify correlates of whole blood metal concentrations among reproductive-aged Black women.

METHODS

We analyzed cross-sectional data from a cohort of 1664 Black women aged 23-35 years in Detroit, Michigan, 2010-2012. We collected blood samples and questionnaire data. We measured concentrations of 17 metals in whole blood using inductively-coupled plasma-mass spectrometer-triple quadrupole and total mercury using Direct Mercury Analyzer-80. We used multivariable linear regression models to identify sociodemographic, environmental, reproductive, and dietary correlates of individual metal concentrations.

RESULTS

In adjusted models, age was positively associated with multiple metals, including arsenic, cadmium, and mercury. Education and income were inversely associated with cadmium and lead. Current smoking was strongly, positively associated with cadmium and lead. Alcohol intake in the past year was positively associated with arsenic, barium, copper, lead, mercury, vanadium, and zinc. Having pumped gasoline in the past 24 h was positively associated with cadmium, chromium, and molybdenum. Having lived in an urban area for the majority of residence in Michigan was positively associated with arsenic, lead, and nickel. Higher water intake in the past year was positively associated with several metals, including lead. Fish intake in the past year was positively associated with arsenic, cesium, and mercury. We also observed associations with body mass index, season, and other environmental, reproductive, and dietary factors.

SIGNIFICANCE

We identified potential sources of exposure to metals among reproductive-aged Black women. Our findings improve understanding of exposures to metals among non-pregnant reproductive-aged women, and can inform policies in support of reducing disparities in exposures.

IMPACT STATEMENT

There are racial disparities in exposures to metals. We analyzed correlates of blood metal concentrations among reproductive-aged Black women in the Detroit, Michigan metropolitan area. We identified sociodemographic, anthropometric, lifestyle, environmental, reproductive, and dietary correlates of metal body burden. Age was positively associated with several metals. Education and income were inversely associated with cadmium and lead, indicating socioeconomic disparities. We identified potential exposure sources of metals among reproductive-aged Black women, including smoking, environmental tobacco smoke, pumping gasoline, living in an urban area, and intake of alcohol, water, fish, and rice.

Associations between exposure to cadmium, lead, mercury and mixtures and women's infertility and long-term amenorrhea

BACKGROUND

Cadmium (Cd), lead (Pb), and mercury (Hg) have been shown to exhibit endocrine disrupting properties. Their effects on women's reproductive health, however, remain elusive. Here, we investigated associations between blood concentrations of Pb, Cd, Hg, and their mixture and infertility and long-term amenorrhea in women aged 20-49 years using the US National Health and Nutrition Examination Survey (NHANES) 2013-2018 cross-sectional survey.

METHODS

A total of 1,990 women were included for the analysis of infertility and 1,919 women for long-term amenorrhea. The methods of log-transformation and use of quartiles were used to analyze blood heavy metal concentrations. Statistical differences in the covariates between the outcome groups were evaluated using a chi-squared test for categorical variables and a t-test for continuous variables. Multiple logistic regression models were used to examine the associations.

RESULTS

The blood concentrations of Pb and heavy metal mixtures were significantly higher in ever-infertile women than pregnant women, but the concentrations of Cd and Hg were comparable. After full adjustment, multiple logistic regression analyses revealed a significant and dose-dependent positive association between blood Pb concentrations and women's historical infertility, a negative association between Cd and women's long-term amenorrhea, and no associations between Hg and heavy metal mixture and women's infertility or long-term amenorrhea.

CONCLUSIONS

Our study suggests that exposure to heavy metals exhibit differential associations with history of infertility and amenorrhea, and Pb may adversely impact women's reproduction and heighten the risks of infertility and long-term amenorrhea.

Heavy Metals and Essential Elements in Association with Oxidative Stress in Women with Polycystic Ovary Syndrome-A Systematic Review

Altered levels of heavy metals and essential elements have been associated with oxidative stress (OS) and metabolic and hormonal changes in women with polycystic ovary syndrome (PCOS). We aimed to summarize the knowledge on the association of heavy metals and essential elements with OS in PCOS. An electronic literature search using PubMed for studies published between January 2008 and April 2023 was conducted. We evaluated heavy metals and essential elements in relation to OS in PCOS in 15 articles. PCOS women had increased antimonium (Sb), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), tellurium (Te), thallium (Tl) and osmium (Os) blood levels and decreased zinc (Zn) blood levels; the results of copper (Cu) blood levels were conflicting. Some studies showed a significant correlation between heavy metals (Sb, Cd, Pb, Hg, As, Te and Tl) and essential elements (Se, Zn, Cr, Ca, Mg and Cu) and markers of OS and chronic inflammation. Heavy metals (Sb, Cd, Pb and Hg) and essential elements (Zn, Cr, Se, Ca, Mg and Cu) were associated with metabolic and hormonal characteristics in PCOS. There might be a possible benefit from supplementation therapy in reducing OS and endocrinological problems related to PCOS. Our review confirmed an association between heavy metals and essential elements with OS in PCOS women. This systematic review is registered in PROSPERO under number CRD42023418453.

Prenatal Cadmium Exposure and Maternal Sex Steroid Hormone Concentrations across Pregnancy

Cadmium exposure has been associated with adverse perinatal outcomes. One possible mechanism is endocrine disruption. Studies of non-pregnant adults suggest that cadmium impacts androgen production; here, we examined these associations during pregnancy. Participants in the Understanding Pregnancy Signals and Infant Development (UPSIDE) cohort provided biospecimens and questionnaire data in each trimester (n = 272). We quantified urinary cadmium, serum total testosterone (TT), estrone, estradiol, and estriol and serum free testosterone (fT). In adjusted longitudinal models, we examined sex steroid concentrations across pregnancy in relation to specific gravity-adjusted, ln-transformed cadmium concentrations. Additionally, we examined trimester-specific associations and stratified models by fetal sex. Results are presented as percent change (%∆) in hormone concentrations. In longitudinal models, higher cadmium concentrations were associated with lower fT across pregnancy (%∆ = -5.19, 95%CI: -8.33, -1.93), with no differences in other hormones observed. In trimester-specific models, higher cadmium concentrations were associated with lower TT in trimester 2 (%∆ = -15.26, 95%CI: -25.15, -4.06) and lower fT in trimester 3 (%∆ = -14.35, 95%CI: -19.75, -8.59). Associations with TT were stronger in pregnancies carrying female fetuses. Maternal cadmium exposure may be associated with reduced testosterone in pregnancy. Additional work is necessary to understand how alterations in gestational testosterone activity may impact pregnancy and child health.

Cannabis smoking, tobacco cigarette smoking, and adenomyosis risk

OBJECTIVE

To investigate cannabis smoking and tobacco cigarette smoking in relation to adenomyosis risk.

DESIGN

We used data from a case-control study of adenomyosis conducted among enrollees ages 18-59 years of an integrated health care system in Washington State. The case-control study used 2 control groups given the challenge of selecting noncases when cases are diagnosed by hysterectomy.

SUBJECTS

Cases (n = 386) were enrollees with incident, pathology-confirmed adenomyosis diagnosed between April 1, 2001, and March 31, 2006. The 2 control groups comprised hysterectomy controls (n = 233) with pathology-confirmed absence of adenomyosis and population controls (n = 323) with an intact uterus selected randomly from the health care system population and frequency matched to cases on age.

EXPOSURE

Detailed data on cannabis and tobacco cigarette smoking history were ascertained through in-person structured interviews, allowing estimation of joint-years of cannabis smoking and pack-years of tobacco cigarette smoking.

MAIN OUTCOME MEASURES

Odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between cannabis smoking, tobacco cigarette smoking, and adenomyosis were estimated using multivariable unconditional logistic regression. Analyses were adjusted for age, reference year, menarche age, education, and pack-years of cigarette smoking (or joint-years of cannabis smoking).

RESULTS

No association was observed between cannabis smoking history and adenomyosis risk. However, we did observe the suggestion of an association between ever tobacco cigarette smoking and adenomyosis risk, comparing cases to hysterectomy controls (OR, 1.3; 95% CI, 0.9-1.9) and population controls (OR, 1.2; 95% CI, 0.8-1.8). Our data suggested a 50% increased odds of adenomyosis with >15 pack-years of smoking (vs. never smoking), comparing cases to hysterectomy controls (OR, 1.5; 95% CI, 0.9-2.6; Ptrend=.135). The suggestion of a 40% increased adenomyosis odds was observed with smoking >5-15 pack-years (vs. never smoking), comparing cases to population controls (OR, 1.4; 95% CI, 0.8-2.4; Ptrend=0.136).

CONCLUSION

In the first study of cannabis smoking and adenomyosis risk, no association was observed. However, our data suggested an increased odds of adenomyosis with history of tobacco cigarette smoking. Further research is warranted to replicate our results given the substantial morbidity with adenomyosis and frequency of cigarette smoking and recreational and medical cannabis use.

Sex differences in cadmium and lead concentrations in different biological matrices in athletes. Relationship with iron status

PURPOSE

The present study aimed to analyse sex differences in cadmium and lead concentrations in plasma, urine, platelets and erythrocytes and to relate these concentrations to biomarkers of iron status.

METHODS

A total of 138 soccer players divided according to sex: men (n = 68) and women (n = 70) participated in the present study. All participants resided in the city of Cáceres (Spain). Erythrocyte, haemoglobin, platelet, plateletcrit, ferritin and serum iron values were determined. Cadmium and lead concentrations were quantified by inductively coupled plasma mass spectrometry.

RESULTS

The women had lower haemoglobin, erythrocyte, ferritin and serum iron values (p < 0.01). Regarding cadmium, the women showed higher concentrations in plasma, erythrocytes and platelets (p < 0.05). As for lead, they also showed higher concentrations in plasma, relative values of erythrocytes and relative values of platelets (p < 0.05). Significant correlations were observed between cadmium and lead concentrations with biomarkers of iron status.

CONCLUSIONS

Cadmium and lead concentrations are different between sexes. Biological differences between sexes and iron status could influence cadmium and lead concentrations. Lower serum iron concentrations and markers of Fe status increase Cd and Pb concentrations. Ferritin and serum iron have been directly related to increased Cd and Pb excretion.

An exposure to endocrine active persistent pollutants and endometriosis - a review of current epidemiological studies

Widespread exposure to persistent pollutants can disrupt the bodies' natural endocrine functions and contribute to reproductive diseases like endometriosis. In this review, we focus at the relationship between endocrine-disrupting chemicals (EDCs), including metals and trace elements, organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), poly-brominated diphenyl ethers (PBDEs), polychlorinated dibenzodioxin (PCDDs), polychlorinated dibenzofurans (PCDFs), and per- and polyfluoroalkyl substances (PFAS) exposure and risk of endometriosis. Relevant studies from the last 10 years by November 2022 were identified by searching Pubmed, Web of Science, and Scopus. The cohort and case-control studies that reported effect size with 95% confidence intervals (CIs) of EDC exposure and endometriosis were selected. Twenty three articles examining the relationship between endometriosis and exposure to persistent EDCs were considered. Most of the studies indicated association with exposure to persistent chemicals and development of endometriosis. The consistent results were found in case of lead, PCB-28, PCB-138, PCB-153, PCB-180, PCB-201, 1,2,3,7,8 - PeCDD, 2,3,4,7,8 - PeCDF and all described OCPs, showing the increased risk of endometriosis. These results support that exposure to certain EDCs, including OCPs, PCBs, PBBs, PBDEs, PFAS, and lead increase the risk of endometriosis.

Exposure to heavy metals and hormone levels in midlife women: The Study of Women's Health Across the Nation (SWAN)

Exposure to heavy metals may alter the circulating levels of sex hormones. However, epidemiologic studies on heavy metals and sex hormones have been limited, and results have been inconsistent. We assessed the associations of heavy metals assayed in urine, including arsenic, cadmium, lead, and mercury, with repeated measures of serum estradiol (E2), follicle-stimulating hormone (FSH), testosterone, and sex hormone-binding globulin (SHBG) levels in the Study of Women's Health Across the Nation Multi-Pollutant Study. The sample included 1355 White, Black, Chinese, and Japanese women, aged 45-56 years at baseline (1999-2000), whose serum hormone levels were repeatedly measured through 2017. Urinary metal concentrations were measured at baseline. Linear mixed effect models were used to calculate percent changes in serum hormone levels per doubling of urinary metal concentrations, adjusting for demographics, socioeconomic status, lifestyle, health-related factors, and urinary creatinine. After multivariable adjustment, a doubling of urinary metal concentration was associated with lower E2 levels by 2.2% (95% CI: 4.0%, -0.3%) for mercury and 3.6% (95% CI: 5.7%, -1.6%) for lead; higher FSH levels by 3.4% (95% CI: 0.9%, 5.9%) for lead; and higher SHBG levels by 3.6% (95% CI: 1.3%, 5.9%) for cadmium. The overall joint effect using the Bayesian kernel machine regression showed that metal mixtures were inversely associated with E2 and positively associated with FSH levels. No association was found between metals and testosterone levels. Results from this prospective cohort study demonstrate that environmental heavy metal exposures, including cadmium, mercury, and lead, may disturb circulating levels of E2, FSH, and SHBG in midlife women.

Transition metallo-curcumin complexes: a new hope for endometriosis?

Endometriosis is a debilitating gynecological disorder in women of reproductive age. Laparoscopy, a minimally invasive surgical procedure, provides a definitive diagnosis of the disease. Current treatments, including hormonal therapy and pain medication, are often associated with undesirable side effects limiting their long-term usage. This calls for exploring newer diagnostic and therapeutic options with minimal side effects. Curcumin is an established anti-endometriotic agent with inherent fluorescent properties; however, poor bioavailability limits its clinical utility. To address this shortcoming, various transition metals were conjugated with curcumin to improve its stability, specificity and pharmacological properties. The chemical stability, hemocompatibility and ability of the synthesized metallo-curcumin complexes (MCCs) to ameliorate endometriotic lesions were investigated. While all of the MCCs exhibited low hemolytic activity, their chemical and biological activities were largely dependent on the nature of the metal ion conjugated to the curcumin molecule. Copper-curcumin and nickel-curcumin complexes demonstrated superior therapeutic efficacy evidenced by enhanced antioxidant activity, selective cytotoxicity and increased accumulation in endometriotic cells mediated by an energy-dependent active transport process.

Heavy metals and metalloids exposure and in vitro fertilization: Critical concerns in human reproductive medicine

Exposures to heavy metals and metalloids have been associated with decreased fecundity and fertility in couples conceiving via assisted reproduction. Heavy metals and metalloids can alter the homeostasis of critical hormones controlling sexual maturation by binding to critical hormones and receptors. This may disrupt the time course of sexual maturation directly or indirectly affecting reproductive competence in males and females. The present review aims to provide a summarized overview of associations between heavy metal exposure, reproductive concerns, and IVF outcomes. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) in Google Scholar, Scopus, EMBASE and PubMed databases. Initial search produced 1,351 articles from which 30 articles were eligible to be included in the systematic review. From our results, 16 articles reported associations between selected heavy metals and IVF outcomes, while 14 articles summarized the role of heavy metals in reproductive concerns. For the studies on IVF outcomes, different human samples were examined for heavy metals. Heavy metals and metalloids (Pb, Hg, Cd, Cr, Mn, As) correlated negatively with oocyte fertilization/pregnancy rates in hair, follicular fluid, serum, urine and seminal plasma samples, while Cd and Hg in whole blood samples showed no associations. For the studies on reproductive concerns, high levels of heavy metals/metalloids were implicated in the following conditions: infertility (Cd, Pb, Ba, U), spontaneous abortion/miscarriage (Pb, Cd, Sb), congenital heart disease (Al, Mg, Cd), PCOS (As, Cd, Hg, Pb), endometriosis (Pb) and uterine leiomyomata (Hg). Taken together, the results of our study suggest that the impact of heavy metals and metalloids exposure on reproductive health may contribute to the failure rates of in vitro fertilization.

Associations between environmental exposures in the Middle East Area of Operations and pregnancy outcomes in Australian Defence Force veterans

Military personnel deployed on operations may encounter a variety of hazards with the capacity to adversely affect reproductive health. This paper investigates the association between self-reported exposure to reproductive toxicants and adverse pregnancy outcomes in Australian Defence Force veterans who deployed to Iraq and Afghanistan during the period 2001-2009. Utilising the Middle East Area of Operations (MEAO) Census Study data set, descriptive analyses of participants' self-reported exposure were compared with the occupational environmental monitoring data taken at their reported deployment location. Univariate analyses assessed the significance of unadjusted associations between self-reported exposures and reproductive outcomes. There is no systematic or consistent relationship between deployment to the MEAO and adverse pregnancy outcomes. Overall, self-reported adverse reproductive outcomes were significantly increased in veterans who deployed to both Afghanistan and Iraq (p = 0.04) compared to those who only deployed to only one of those locations; particularly in women (p = 0.009). Miscarriage was the most likely of these (p = 0.008). These figures would benefit from being confirmed against medical records but are worthy of further study. In this historical cohort study, causal inference cannot be made due to absence of control groups to exclude sources of potential bias. Imprecision in the assessment of environmental hazards in the MEAO and other methodological constraints make it impossible to calculate precise estimates of risk. The results warrant continued investigation, especially when combined with previous findings related to pregnancy outcomes in this population, the importance of reproductive outcomes, and the potential emergence of new hazards.

Associations between hair levels of trace elements and the risk of preterm birth among pregnant Wwomen: A prospective nested case-control study in Beijing Birth Cohort (BBC), China

Trace elements have various physiochemical functions in humans and are associated with the occurrence of preterm birth (PB). However, their mixed effects on PB risk have rarely been studied. We aimed to investigate the associations between hair levels of trace elements and PB risk among pregnant women. A nested case-control study with a prospective cohort was conducted in Beijing City, China. We included 82 women who had a PB [total PB (tPB)] as cases [including 40 with a spontaneous PB (SPB)] and 415 who had a term delivery as controls. Hair levels of the concerned trace elements were measured including endocrine disrupting metal(loid)s [EDMs; lead, mercury (Hg), arsenic, and cadmium] and nutritional trace metal(loid)s [NTMs; zinc (Zn), iron (Fe), copper, and selenium]. Logistic regression analysis was performed to estimate the odds ratios (ORs) for PB. Bayesian kernel machine regression (BKMR) was used to assess the associations between mixed exposure to the trace elements and PB risk. Significantly lower maternal hair concentrations of Zn and Fe were observed in the SPB cases than in the controls, whereas no differences for the other trace elements. Single-element modeling results suggested second-quartile Hg maternal hair concentrations, third-quartile Zn concentrations, and fourth-quartile Fe concentrations were associated with a reduced risk of tPB with adjusted ORs of 0.43 [95% confidence interval (CI): 0.21-0.87], 0.38 (95% CI: 0.18-0.82), and 0.48 (95% CI: 0.24-0.98), respectively, compared to first-quartile values. Similar results were obtained for SPB. According to the BKMR models, hair NTMs were significantly, monotonously, and inversely associated with the risk of SPB, after controlling for covariates and levels of the four EDMs. Fe and Zn contributed the most strongly to the association. We concluded that maternal higher levels of NTMs, especially Fe and Zn, may reduce the risk of PB.

Antioxidant status in relation to heavy metals induced oxidative stress in patients with polycystic ovarian syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is a global health concern for women of reproductive age, as 6.5% of women worldwide are affected by this syndrome. PCOS is marked by hyperandrogenism, anovulation, menstrual abnormalities, and polycystic ovaries. Metals such as arsenic, cadmium, lead and mercury are considered to be systemic toxicants/human carcinogens and seem to have devastating effects on humans, even at minimal exposures. One of the probable aetiological factors for PCOS has been identified as oxidative stress. In view of the probable associations among oxidative stress, metal toxicity and PCOS, the present study examined the role of heavy metals in the generation of oxidative stress among females. This prospective study included 106 women (56 women diagnosed with PCOS and 50 women who were not diagnosed with PCOS as control women). There were no significant differences in the sociodemographic characteristics between the two groups except for the irregularity of menses and the presence of acne. The serum As, Cd, Pb, and Hg levels increased and the serum glutathione (GSH) and superoxide dismutase (SOD) levels diminished significantly in the PCOS group compared to the control group at P < 0.001. The SOD levels were negatively correlated with the As and Pb levels at P < 0.05. Additionally, the PCOS group exhibited a strong negative correlation between the GSH and As levels (P < 0.01), GSH and Pb levels (P < 0.05) and GSH and Hg levels (P < 0.01). Furthermore, the As levels were positively correlated with increased levels of Cd, Pb and Hg among PCOS women. Significant positive correlations were observed between Pb and Cd and between Cd and Hg at P < 0.001. The outcome of the study provides clear insight into the role of metal-induced oxidative stress, which plays a vital role in the pathophysiology underlying PCOS and suggests the use of these markers as prognostic tools to reduce the consequences of high-risk exposure to these metals among females.

Associations between blood cadmium and endocrine features related to PCOS-phenotypes in healthy women of reproductive age: a prospective cohort study

BACKGROUND

Cadmium is an endocrine disrupting chemical that affects the hypothalamic-pituitary-gonadal axis. Though evidence suggests its potential role in altering androgen synthesis and metabolic pathways that are characteristic of polycystic ovary syndrome (PCOS), its relation in healthy women of reproductive age is largely unknown. As women with mild sub-clinical features of PCOS who do not meet the diagnostic criteria of PCOS may still experience reduced fecundability, investigating associations between cadmium and PCOS-phenotypes among healthy women may provide unique insight into the reproductive implications for many on the PCOS spectrum. Therefore, the objective of this study was to evaluate associations between cadmium and androgens, anti-Müllerian hormone (AMH), and metabolic markers in women of reproductive age.

METHODS

This was a prospective cohort study of 251 healthy premenopausal women without self-reported PCOS (mean age 27.3 years and BMI 24.1 kg/m²). Cadmium was measured in blood collected at baseline. Reproductive hormones and metabolic markers were measured in fasting serum 8 times per menstrual cycle for 2 cycles. Linear mixed models and Poisson regression with a robust error variance were used to examine associations between cadmium and reproductive hormones and metabolic markers and anovulation, respectively.

RESULTS

Median (interquartile range) blood cadmium concentrations at baseline were 0.30 (0.19-0.43) µg/L. Higher levels of testosterone (2.2 %, 95 % confidence interval [CI] 0.4, 4.1), sex hormone-binding globulin (2.9 %, 95 % CI 0.5, 5.5), and AMH (7.7 %, 95 % CI 1.1, 14.9) were observed per 0.1 µg/L increase in cadmium concentrations. An 18 % higher probability of a mild PCOS-phenotype (95 % CI 1.06, 1.31), defined by a menstrual cycle being in the highest quartile of cycle-averaged testosterone and AMH levels, was also found per 0.1 µg/L increase in cadmium levels. No associations were observed for insulin and glucose. These findings were consistent even after analyses were restricted to non-smokers or further adjusted for dietary factors to account for potential sources of exposure.

CONCLUSIONS

Overall, among healthy reproductive-aged women, cadmium was associated with endocrine features central to PCOS, but not with metabolic markers. These suggest its potential role in the hormonal milieu associated with PCOS even at low levels of exposure.

Cadmium Exposure and Ovarian Reserve in Women Aged 35-49 Years: The Impact on Results From the Creatinine Adjustment Approach Used to Correct for Urinary Dilution

Cadmium is toxic to the ovaries in animal studies, but its association with diminished ovarian reserve in women is not established. We investigated urinary cadmium, a biomarker of long-term exposure, in relation to diminished ovarian reserve, as indicated by elevated serum follicle-stimulating hormone concentrations (≥10 IU/L), in women aged 35-49 years (unweighted n = 1,681). Using data from the Third National Health and Nutrition Examination Survey (1988-1994), we conducted Poisson regression to estimate adjusted relative risks and 95% confidence intervals. Because the best approach to correcting for urinary dilution in spot samples with creatinine remains controversial, we employed 3 approaches: standardization, covariate adjustment, and covariate-adjusted standardization. Our data suggested a modest association with standardization (highest quartile vs. lowest: relative risk (RR) = 1.3, 95% confidence interval (CI): 0.8, 1.9; P for trend = 0.06) and covariate-adjusted standardization (highest quartile vs. lowest: RR = 1.3, 95% CI: 0.9, 1.9; P for trend = 0.05) and a stronger association with covariate adjustment (highest quartile vs. lowest: RR = 1.8, 95% CI: 1.2, 2.9; P for trend = 0.01). The stronger association with covariate adjustment may reflect bias from conditioning on urinary creatinine, a collider in the hypothesized causal pathway. We conclude that cadmium may contribute to ovarian aging in women and that careful consideration of the creatinine adjustment approach is needed to minimize bias.

Are Heavy Metal Exposure and Trace Element Levels Related to Metabolic and Endocrine Problems in Polycystic Ovary Syndrome?

This study aimed to determine the relationship between the metabolic and endocrinological pathologies in polycystic ovary syndrome (PCOS) and the levels of arsenic, chromium, cadmium, lead, mercury, antimony, zinc, and copper to evaluate the relationship of these toxic metals with inflammatory/oxidative parameters. This study included a total of 154 patients (84 with PCOS, 70 healthy volunteers). Metabolic and endocrine parameters and arsenic, chromium, cadmium, lead, mercury, antimony, zinc, and copper serum levels of the patients were compared between the groups. Considering the action mechanism of toxic metals, serum malondialdehyde (MDA), superoxide dismutase (SOD), serum total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), tumor necrosis factor-alpha (TNFα), and high-sensitivity C-reactive protein (HsCRP) levels were determined. Serum TAS (p = 0.002), OSI (p = 0.006), SOD (p = 0.006), zinc (p = 0.010), and copper (p = 0.030) values were statistically lower whereas TOS (p = 0.008), MDA (p < 0.001), HsCRP (p < 0.001), TNFα (p < 0.001), antimony (p < 0.001), cadmium (p < 0.001), lead (p < 0.001), and mercury (p < 0.001) levels were significantly higher in the PCOS group than those determined in the control group. Antimony was positively correlated with fasting glucose (FG) and HOMA-IR while cadmium, in addition to FG and HOMA-IR, positively correlated with insulin and lead had a positive correlation only with FG (p < 0.05). Also, these three heavy metals correlated positively with some oxidative system and inflammatory parameters and negatively with the antioxidant system parameters (p < 0.05). In conclusion, heavy metal exposures in PCOS may be related to insulin resistance and hirsutism through oxidative and inflammatory mechanisms. This approach can be used to identify the risky patient group and to develop new treatment modalities.

Cadmium toxicity: effects on human reproduction and fertility

Background Cadmium (Cd) is a non-essential toxic heavy metal, an environmental toxicant, and toxic at a low concentration, and it has no known beneficial role in the human body. Its exposure induces various health impairments including hostile reproductive health. Objective The present review discusses the information on exposure to Cd and human reproductive health impairments including pregnancy or its outcome with respect to environmental and occupational exposure. Methods The present review provides current information on the reproductive toxic potential of Cd in humans. The data were collected using various websites and consulting books, reports, etc. We have included recent data which were published from 2000 onward in this review. Results Cd exposure affects human male reproductive organs/system and deteriorates spermatogenesis, semen quality especially sperm motility and hormonal synthesis/release. Based on experimental and human studies, it also impairs female reproduction and reproductive hormonal balance and affects menstrual cycles. Based on the literature, it might be concluded that exposure to Cd at low doses has adverse effects on both human male and female reproduction and affects pregnancy or its outcome. Further, maternal prenatal Cd exposure might have a differential effect on male and female offspring especially affecting more female offspring. Hence, efforts must be made to prevent exposure to Cd. Conclusion Cd affects both male and female reproduction, impairs hormone synthesis/regulation and deteriorates pregnancy rate or its outcome even at lower doses.

Subchronic Exposure to Cadmium Causes Persistent Changes in the Reproductive System in Female Wistar Rats

Cadmium (Cd) is an environmental toxicant and endocrine disruptor in humans and animals, and recent studies have illustrated that the uterus is exceedingly sensitive to Cd toxicity. The aim of the study was to investigate the influence of subchronic (90 days) oral Cd exposure in daily doses of 0.09-4.5 mg/kg b.w. on the balance of sex hormones by estimating estradiol (E₂) and progesterone (P) concentrations in the uterus and plasma in comparison with the effects of 17β-E₂. Additionally, the uterine weight, histopathological changes in the uterus and ovaries, the regularity of the estrous cycle, Cd bioaccumulation in uterine tissue, and selected biochemical parameters of oxidative stress were determined. A long period of observation (three and six months following the administration period) was used to assess whether the existing effects are reversible. The lowest dose of Cd caused effects similar to 17β-E₂: an increase of E₂ concentration in the uterus, endometrial epithelium thickness, and disturbed estrous cycle with estrus phase prolongation. The obtained results suggest that Cd causes nonlinear response. Higher doses of Cd caused a significant decrease in E₂ concentration in the uterus and plasma, estrous cycle disturbances, endometrium atrophy, and structural damage in the ovaries. This dose additionally induces lipid peroxidation in the uterine tissues. It is noteworthy that a prolonged time of observation after terminating the exposure showed persistent changes in the concentration of E₂ in uterine tissue, as well as alterations in estrous cycle phases, and an increase in lipid peroxidation in the uterus. Moreover, significant positive correlations between the plasma E₂ concentration and endometrial epithelium thickness in all studied groups were found. In summary, subchronic oral Cd exposure of female rats may result in impaired fertility processes.

Exposure to mercury and human reproductive health: A systematic review

BACKGROUND

Evidences from human and animal studies suggest that reproductive function may be affected by mercury. The aim of this review was to explore the mercury influence on human fertility.

METHODS

A systematic search was made in PubMED for papers published between 1975-2017, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Increased mercury levels were associated with infertility or subfertility status. Further, infertile subjects with unexplained infertility showed higher levels of mercury in hair, blood and urine than fertile ones. Mercury exposure induced sperm DNA damage and abnormal sperm morphology and motility. Additionally, mercury levels were related with higher incidence of menstrual and hormonal disorders and increased rates of adverse reproductive outcomes.

CONCLUSIONS

Our review showed that mercury negatively impacts human reproduction, affecting the reproductive and endocrine systems in both male and female. However, the molecular mechanisms underlying the mercury-associated decline on fertility remains unknown.

Influence of tobacco smoke on zinc, cadmium, iron, iron-binding proteins, and low-weight anti-oxidant status in pregnancy

Pregnancy and tobacco smoking (TS) each can cause increases in reactive oxygen species (ROS) production; this, in turn, can lead to disorders in iron management and disruption of the pro- and anti-oxidant balance. The aim of the study was to analyze the influence of TS and Cd on Fe, Zn, and anti-oxidant levels (i.e. glutathione [GSH], metallothionein [MT]) in the blood of pregnant women. The study reported here evaluated 110 blood samples from pregnant women in their 1st, 2nd and 3rd trimester. Concentrations of ferritin and transferrin were measured in the serum; Zn, Fe and cotinine in the plasma, that of Cd in whole blood, that for glutathione in red blood cell lysates, and levels of metallothionein both in the plasma and in lysates prepared from isolated erythrocytes. The results indicated there was a decrease in Zn and increase in Cd and metallothionein levels in pregnant women smokers as compared to in nonsmoking counterparts. Differences in intracellular MT concentration were noted both in smoking and nonsmoking women during pregnancy while there were no changes in extracellular MT level. A decline in circulating ferritin and a rise in transferrin during pregnancy was observed in all groups. Based on the results, it was concluded that exposure to TS-associated xenobiotics like Cd could result in higher MT levels in erythrocytes and in pregnant smokers, the major anti-oxidant mechanism that is in place is one being mediated by MT and not by reduced GSH.

Predictors of mercury, lead, cadmium and antimony status in Norwegian never-pregnant women of fertile age

Background

The toxic trace elements mercury (Hg), lead (Pb), cadmium (Cd) and antimony (Sb) are transferred over the placenta to the fetus and secreted into the breastmilk. All four elements bioaccumulate in the body and as maternal age at delivery is increasing in industrialized countries, the burden of toxic trace elements in never-pregnant women of fertile age is of concern.

Methods

Healthy, never-pregnant women aged 18 to 40 years (n = 158) were recruited between June 2012 and March 2015 in Bergen, Norway. Clinical data were collected and non-fasting venous blood samples were analyzed for whole blood Hg, Pb and Cd and serum Sb by ICP-MS and related to diet and life style factors.

Results

In a multiple linear regression model, increasing age was associated with higher levels of Hg and Sb, but diet and life style factors were more important predictors. Median whole blood Hg was increased by a factor of 70 in women who had fish for dinner ≥1/week, compared to women who rarely or never ate fish (p<0.001). Alcohol intake was the strongest predictor for whole blood Pb, while use of tobacco was the strongest predictor for whole blood Cd. Being a vegetarian was associated with lower levels of both Hg and Sb.

Conclusions

As toxic trace elements tend to bioaccumulate in the body, increasing maternal age at delivery may represent a threat to the next generation. In a group of healthy Norwegian never-pregnant women, age contributed to Hg and Sb levels, but diet and life style factors were stronger determinants of whole blood Hg, Pb, Cd and serum Sb levels. Continuous public actions are needed to reduce modifiable and preventable sources of potentially deleterious toxins to minimize the exposure in children and fertile women.

Associations of urinary cadmium with circulating sex hormone levels in pre- and postmenopausal Japanese women

BACKGROUND

Exposure to cadmium has been suspected as a risk factor for breast cancer. The present study examined the associations between urinary cadmium levels and circulating sex hormone levels that are linked to breast cancer risk in healthy women.

METHODS

The study subjects were 396 premenopausal Japanese women who had regular menstrual cycles less than 40 days long and 207 postmenopausal Japanese women. Urinary cadmium was measured using spot urine samples. Plasma estradiol, testosterone, and dehydroepiandrosterone sulfate were measured. Additionally, the follicle-stimulating hormone, luteinizing hormone, and sex hormone-binding globulin were measured for premenopausal women.

RESULTS

In premenopausal women, the urinary cadmium level either expressed in μg per liter or per g of urine creatinine was significantly inversely associated with total and free testosterone levels after controlling for age, body mass index, smoking status, alcohol intake, and the phase of the menstrual cycle. Total and free testosterone levels were 14.6% and 15.0% lower, respectively, in women in the highest quartile of urinary cadmium per g creatinine in those in the lowest quartile. In postmenopausal women, the urinary cadmium in μg per liter as well as per g creatinine was significantly inversely associated with the estradiol level after controlling for covariates. The estradiol level was 25.8% lower in women in the highest tertile of urinary cadmium per g creatinine than in those in the lowest tertile.

CONCLUSIONS

The data suggest inverse associations between urinary cadmium and the plasma estradiol or testosterone level in Japanese women.

Menstrual cycle perturbation by organohalogens and elements in the Cree of James Bay, Canada

Persistent organohalogens (POHs) and metals have been linked to alterations in menstrual cycle function and fertility in humans. The Cree First Nations people living near James Bay in Ontario and Quebec, Canada, have elevated levels of POHs, mercury and lead compared to other Canadians. The present study examines the interrelationships between selected POHs and elements on menstrual cycle function in these Cree women. Menstrual cycle characteristics were derived from structured daily diaries and endocrine measurements from daily urine samples collected during one cycle for 42 women age 19-42. We measured 31 POHs in blood plasma and 18 elements in whole blood, for 31 of the participants. POHs and elements detected in ≥ 70% of the participants were transformed by principal component (PC) analysis to reduce the contaminant exposure data to fewer, uncorrelated PCA variables. Multiple regression analysis revealed that, after adjusting for confounders, PC-3 values showed significant negative association with cycle length, after adjusting for confounders (p = 0.002). PC-3 accounted for 9.2% of the variance and shows positive loadings for cadmium, selenium, and PBDE congeners 47 and 153, and a negative loading for copper. Sensitivity analysis of the model to quantify likely effect sizes showed a range of menstrual cycle length from 25.3 to 28.3 days using the lower and upper 95% confidence limits of mean measured contaminant concentrations to predict cycle length. Our observations support the hypothesis that the menstrual cycle function of these women may be altered by exposure to POHs and elements from their environment.

Association of Serum Heavy Metals and Trace Element Concentrations with Reproductive Hormone Levels and Polycystic Ovary Syndrome in a Chinese Population

To investigate the serum concentrations of 11 heavy metals and trace elements in patients with polycystic ovary syndrome (PCOS). A total of 369 women (including 96 patients with PCOS) were studied. No differences with statistical significance in the median barium, cadmium, lead, arsenic, chromium, gallium, strontium, and vanadium concentrations were observed between the patients with PCOS and the control group. Serum nickel (Ni) (P = 0.000) and copper (Cu) (P = 0.000) levels were significantly higher, but zinc (Zn) levels (P = 0.009) were significantly lower in patients with PCOS compared with the control group. The results of the association between metal levels and hormone levels indicated that Ni, Cu, and Zn may play a role in the pathogenesis of PCOS related with reproductive hormone levels. The findings in the present study should be investigated with further trials in order to obtain new insights into PCOS.

Concentration of lead, mercury, cadmium, aluminum, arsenic and manganese in umbilical cord blood of Jamaican newborns

The objective of this study was to characterize the concentrations of lead, mercury, cadmium, aluminum, and manganese in umbilical cord blood of Jamaican newborns and to explore the possible association between concentrations of these elements and certain birth outcomes. Based on data from 100 pregnant mothers and their 100 newborns who were enrolled from Jamaica in 2011, the arithmetic mean (standard deviation) concentrations of cord blood lead, mercury, aluminum, and manganese were 0.8 (1.3 μg/dL), 4.4 (2.4 μg/L), 10.9 (9.2 μg/L), and 43.7 (17.7 μg/L), respectively. In univariable General Linear Models, the geometric mean cord blood aluminum concentration was higher for children whose mothers had completed their education up to high school compared to those whose mothers had any education beyond high school (12.2 μg/L vs. 6.4 μg/L; p < 0.01). After controlling for maternal education level and socio-economic status (through ownership of a family car), the cord blood lead concentration was significantly associated with head circumference (adjusted p < 0.01). Our results not only provide levels of arsenic and the aforementioned metals in cord blood that could serve as a reference for the Jamaican population, but also replicate previously reported significant associations between cord blood lead concentrations and head circumference at birth in other populations.

Associations between cadmium exposure and circulating levels of sex hormones in postmenopausal women

Recent epidemiological as well as in vivo and in vitro studies collectively suggest that the metalloestrogen cadmium (Cd) could be a potential risk factor for hormone-related cancers in particularly breast cancer. Assessment of the association between Cd exposure and levels of endogenous sex hormones is of pivotal importance, as increased levels of such have been associated with a higher risk of breast cancer in postmenopausal women. The present study investigated the perceived relationship (multivariable-adjusted linear regression analyses) between Cd exposure [blood Cd (B-Cd) and urinary Cd (U-Cd)], and serum levels of androstenedione, testosterone, estradiol, and sex-hormone binding globulin (SHBG), in 438 postmenopausal Swedish women without hormone replacement therapy (HRT). A significant positive association between B-Cd (median 3.4 nmol/L) and serum testosterone levels, as well as a significant inverse association between B-Cd and serum estradiol levels and with the estradiol/testosterone ratio were encountered. However, U-Cd (median 0.69 nmol/mmol creatinine) was inversely associated with serum estradiol levels only. Our data may suggest that Cd interferes with the levels of testosterone and estradiol in postmenopausal women, which might have implications for breast cancer risk.

Body burden of Hg in different bio-samples of mothers in Shenyang city, China

Hg is an accumulative and neuro-toxic heavy metal which has a wide range of adverse effects in human health. However, few studies are available on body burden of Hg level in different bio-samples of pregnant women in Chinese population. Therefore, this study evaluated Hg levels in different maternal bio-samples in Shenyang city, China and investigated the correlation of Hg levels in different bio-samples. From October to December 2008, 200 pregnant women about to deliver their babies at ShengJing Hospital (Shenyang city, northeast of China) participated in this study. The geometric mean (GM) of Hg levels in cord blood, maternal venous blood, breast milk, and maternal urine were 2.18 µg/L, 1.17 µg/L, 1.14 µg/L, and 0.73 µg/L, respectively, and the GM of maternal hair Hg level was 404.45 µg/kg. There was a strong correlation between cord blood and maternal blood total Hg level (r = 0.713, P<0.001). Frequency of fish consumption more than or equal to 3 times per week during pregnancy was suggested as a significant risk factor of prenatal Hg exposure (unadjusted OR 3.5, adjusted OR 2.94, P<0.05). This study provides evidence about Hg burden of mothers and the risk factors of prenatal Hg exposure in Shenyang city, China.

Cadmium and Reproductive Health in Women: A Systematic Review of the Epidemiologic Evidence

An evolving body of evidence supports that cadmium, a non-essential heavy metal, may be associated with multiple adverse women's reproductive health outcomes. Our objective was to conduct a systematic review of epidemiologic studies that evaluated cadmium exposure and the following reproductive health outcomes: puberty/menarche, fertility, time to pregnancy, pregnancy loss, preeclampsia, endometriosis, uterine leiomyoma, and menopause. Twenty-two studies were identified based upon our search criteria. Available evidence was inadequate to draw meaningful conclusions for most of the reproductive outcomes studied. The strongest evidence was for a possible association between cadmium and preeclampsia, which was limited to cross-sectional studies. Some evidence, although conflicting, was also observed for fertility related outcomes. This lack of evidence underscores the need for additional research on cadmium and women's reproductive health outcomes.

Cumulative lead exposure and age at menopause in the Nurses' Health Study cohort

BACKGROUND

Early menopause has been associated with many adverse health outcomes, including increased risk of cardiovascular disease morbidity and mortality. Lead has been found to be adversely associated with female reproductive function, but whether exposures experienced by the general population are associated with altered age at menopause has not been explored.

OBJECTIVE

Our goal was to assess the association between cumulative lead exposure and age at natural menopause.

METHODS

Self-reported menopausal status and bone lead concentration measured with K-shell X-ray fluorescence-a biomarker of cumulative lead exposure-were obtained from 434 women participants in the Nurses' Health Study.

RESULTS

The mean (± SD) age at natural menopause was 50.8 ± 3.6 years. Higher tibia lead level was associated with younger age at menopause. In adjusted analyses, the average age of menopause for women in the highest tertile of tibia lead was 1.21 years younger (95% CI: -2.08, -0.35) than for women in the lowest tertile (p-trend = 0.006). Although the number of cases was small (n = 23), the odds ratio for early menopause (< 45 years of age) was 5.30 (95% CI: 1.42, 19.78) for women in the highest tertile of tibia lead compared with those in the lowest tertile (p-trend = 0.006). There was no association between patella or blood lead and age at menopause.

CONCLUSIONS

Our results support an association between low-level cumulative lead exposure and an earlier age at menopause. These data suggest that low-level lead exposure may contribute to menopause-related health outcomes in older women through effects on age at menopause.

CITATION

Eum KD, Weisskopf MG, Nie LH, Hu H, Korrick SA. 2014. Cumulative lead exposure and age at menopause in the Nurses' Health Study Cohort. Environ Health Perspect 122:229–234; http://dx.doi.org/10.1289/ehp.1206399

Exposure to cadmium in male urban and rural workers and effects on FSH, LH and testosterone

OBJECTIVE

This cross-sectional study was conducted to assess the relationship between exposure to cadmium and circulating reproductive hormone levels in urban and rural male workers.

MATERIALS AND METHODS

Urinary cadmium, blood cadmium, luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone were obtained from 86 non-smoking traffic policemen and 86 subjects working as roadmen in a rural area. All subjects were monitored to evaluate airborne exposure to cadmium.

RESULTS

The mean value of exposure to cadmium was 1.3 ng m(-3) in traffic policemen, while the mean value was less than 0.5 ng m(-3) in roadmen. The mean concentrations of urinary cadmium (1.4 vs. 0.9 μg g(-1) creatinine; p=0.001), blood cadmium (1.1 vs. 0.7 μg l(-1); p=0.000), FSH (2.6 vs. 3.2 μlU ml(-1); p=0.02) and LH (2.6 vs. 3.1 μlU ml(-1); p=0.03) were significantly different between traffic policemen and roadmen. No differences were found in the mean values of testosterone between the two groups. Multiple linear regression models showed associations between (a) urinary cadmium, airborne cadmium, working life, job category and consumption of water from water supply (b) blood cadmium, airborne cadmium and job category (c) the values of FSH and age, working life, job category, urinary cadmium and blood cadmium (d) the values of LH and both the age and working life.

CONCLUSION

The above results must be confirmed by further studies, but they indicate the influence of exposure to the cadmium present in urban air on the circulating FSH, even at low doses.

Effect of pregnancy on the levels of urinary metals for females aged 17-39 years old: data from National Health and Nutrition Examination Survey 2003-2010

Data from National Health and Nutrition Examination survey for the years 2003-2010 were used (n = 1565) to evaluate the effect of age, parity, body mass index (BMI), race/ethnicity, pregnancy, iron (Fe) storage status, smoking status, and fish/shellfish consumption on the levels of urine barium (Ba), cadmium (Cd), cesium (Cs), cobalt (Co), molybdenum (Mo), lead (Pb), antimony (Sb), thallium (TI), tungsten (W), uranium (U), and mercury (Hg) for females aged 17-39 yr old. Regression analysis was used to fit models for each of the 11 metals. For Cd, Cs, TI, and Hg, age was positively associated with levels of these metals. Body mass index was negatively associated with levels of Cs, Co, and TI. Levels of Co, Mo, and W increased over the period 2003-2010. Over the same period, levels of Pb, Sb, and Hg declined. Non-Hispanic blacks showed lower levels of almost all metals compared to either Mexican American or other unclassified race/ethnicities. Non-Hispanic whites displayed higher levels than non-Hispanic blacks for 9 of 11 metals. Smokers displayed significantly higher levels of Pb, Sb, W, and U than nonsmokers but significantly lower levels of Cd and Mo than nonsmokers. Pregnancy was found to be associated with higher levels of Ba, Cs, Co, Mo, Pb, W, and Hg compared to nonpregnant females. Levels of Mo, Cs, and Cd declined significantly during the pregnancy period but levels of Co rose during the same period.

Effect of pregnancy on the levels of blood cadmium, lead, and mercury for females aged 17-39 years old: data from National Health and Nutrition Examination Survey 2003-2010

Data from the National Health and Nutrition Examination survey for the years 2003-2010 were used (n = 4700) to evaluate the effect of age, parity, body mass index (BMI), race/ethnicity, pregnancy, iron (Fe) storage status, smoking status, and fish/shellfish consumption on the levels of blood cadmium (Cd), lead (Pb), and total mercury (Hg)for females aged 17-39 years old. Regression analysis was used to fit models for each of the three metals. For all three metals, age was positively and BMI was negatively associated with levels of these metals in blood. Smokers had statistically significantly higher levels of Cd and Pb irrespective of race/ethnicity and Fe storage status as compared to nonsmokers. Novel to this study, pregnancy was found to be associated with significantly lower levels of Cd, Pb, and Hg irrespective of race/ethnicity and Fe storage status as compared to nonpregnant females. It is conceivable that pregnancy may thus accelerate clearance of these metals from blood. Fish/shellfish consumption was associated with higher levels of Hg but not with Cd levels.