Association between the plasma/whole blood lead ratio and history of spontaneous abortion: a nested cross-sectional study

Association between blood lead levels and unfavorable IVF outcomes: potential involvement of endoplasmic reticulum stress response in granulosa cells

PURPOSE

To investigate the relationship between blood lead levels (BLLs) and IVF clinical outcomes in infertile females and to further explore the possible involvement of granulosa cell (GC) endoplasmic reticulum (ER) stress in the process.

METHODS

One hundred twenty-three infertile women undergoing IVF cycles were included in the current study. All participants were divided into three (low, medium, and high) groups determined by BLL tertiles. Gonadotropin releasing hormone (GnRH) agonist regimen for ovarian stimulation was used for all patients, with follicular fluids being collected on the day of oocyte retrieval. Lactate dehydrogenase (LDH) levels in follicular fluid and the endoplasmic reticulum stress-signaling pathway of granulosa cells (GCs) were examined.

RESULTS

The oocyte maturation rate and high-quality embryo rate on cleaved stage decreased significantly as BLL increased. For lead levels from low to high, live birth rate (68.29%, 56.10%, 39.02%; P=0.028) showed negative correlations with BLLs. Also, follicular fluid Pb level and LDH level was significantly higher in the high lead group versus the low group. Binomial regression analysis revealed significant negative correlation between BLLs and live birth rate (adjusted OR, 0.38; 95% CI, 0.15-0.95, P=0.038). Further analysis of the endoplasmic reticulum stress (ER stress) signaling pathway of GCs found that expressions of GRP78, total JNK, phosphorylated JNK, and CHOP increased and BCL-2 decreased with increasing BLLs.

CONCLUSIONS

BLLs are negatively associated with final clinical outcomes in IVF patients that may be related to increased ER stress response and GC apoptosis. Thus, reducing Pb exposure before IVF procedures may improve final success rates.

Exposure of Reproductive-Aged Women to Multiple Metals and Its Associations with Unexplained Recurrent Miscarriage

Exposure to heavy metals exerts toxic effects on female reproduction and embryo development. This study examined the exposure of patients with unexplained recurrent miscarriage (uRM) to multiple metals and the correlations among exposures to different metals. A total of 275 participants were enrolled, including 43 healthy women without previous miscarriage (the control group) and 232 uRM women (the case group); among these uRM women, 159 had two miscarriages (2M), 42 had three miscarriages (3M) and 31 had four or more miscarriages (≥4M). A total of 22 elements were measured in serum samples via inductively coupled plasma-mass spectrometry. The levels of calcium (104.37 mg/L vs. 92.65/93.02/92.61/92.47 mg/L) and selenium (131.85 µg/L vs. 117.80/118.04/115.88/124.35 µg/L) were higher in the controls than in the total uRM group and the 2M, 3M and ≥4M subgroups. The level of vanadium was significantly lower in the controls than in the total uRM group (0.15 µg/L vs. 0.23 µg/L), and the level of lead was lower in the controls than that in the total uRM group and the 2M, 3M and ≥4M subgroups (0.01 µg/L vs. 0.28/0.18/0.63/0.34 µg/L). After adjusting for age, body mass index and education level, calcium and selenium exposure were consistently negatively associated with miscarriage, while lead exposure was positively associated with miscarriage. In addition, the correlations among exposures to different metals slightly differed between the control and uRM groups. Therefore, changes in some metal elements in the blood might be related to the risk of uRM.

Association between female circulating heavy metal concentration and abortion: a systematic review and meta-analysis

Objective

This study aimed to evaluate the association between blood heavy metal (zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd)) concentrations and spontaneous abortion (SA) and recurrent pregnancy loss (RPL) and explore the possible endocrine dysfunction associated with it.

Methods

A literature search was performed in the PubMed, Embase, Cochrane Library, and Web of Science databases up to April 2023. The overall effects were expressed as the standard mean difference (SMD). Subgroup analysis was performed according to the type of abortion (SA or RPL). Stata 16.0 was utilized for data analysis.

Results

Based on the integrated findings, abortion women showed significantly lower Zn (SMD = -1.05, 95% CI: -1.74 to -0.36, p = 0.003) and Cu concentrations (SMD = -1.42, 95% CI: -1.97 to -0.87, p <0.001) and higher Pb (SMD = 1.47, 95% CI: 0.89-2.05, p <0.001) and Cd concentrations (SMD = 1.15, 95% CI: 0.45-1.85, p = 0.001) than normal pregnant women. Subgroup analysis showed that Zn and Cu deficiency and Cd and Pb exposure were significantly (p <0.05) associated with RPL, whereas Cu deficiency and Cd and Pb exposure were significantly (p <0.05) associated with SA.

Conclusion

Zn and Cu deficiencies and Pb and Cd exposure were associated with abortion. Endocrine dysfunction, such as insulin resistance, vitamin D insufficiency, and abnormal thyroid and sex hormone concentrations, is thought to be involved in heavy metal-related abortion.

Investigation of the levels of essential and non-essential metals in women with and without abortion history: A study based on the Persian population of the Shahrekord cohort

Spontaneous abortion is a serious threat to the mothers' physical and mental well-being. The cause of spontaneous abortion is multifactorial disease. Prenatal non-essential metal exposure, particularly heavy metals, has been suggested to be associated with adverse pregnancy and birth outcomes. The purpose of this study was to investigate the relationship between the concentration of essential and non-essential metals including Pb, As, Zn, and Se and the risk of spontaneous abortion. In this case-control study the levels of Pb, As, Zn, and Se in the whole blood of 60 women with spontaneous abortion (case group) and also 60 women without spontaneous abortion (control group) were measured by atomic absorption spectrophotometry. Results revealed statistically significant reductions (P < 0.001) in whole blood levels of Zn and Se as well as the levels of As and Pb had a substantial elevation (P < 0.001) in cases compared to controls. According to the findings, repeated spontaneous abortion may be influenced by increasing whole blood levels of heavy metals such as As (OR = 17.53, P = 0.001) and Pb (OR = 15.58, P = 0.001) as well as decreasing levels of vital micronutrients Zn (OR = 0.20, P = 0.001) and Se (OR = 0.14, P = 0.001). The results of this study support the idea that limiting intake of non-essential metals during pregnancy can decrease the risk of spontaneous abortion. Overall, the information presented is expected to help plan future fundamental and applied investigations on the spontaneous abortion.

Knowledge, confidence, and reported behaviors that promote safe water drinking among women of reproductive age

Introduction

Drinking lead contaminated water during pregnancy is associated with infant mortality. All women of reproductive age are advised by health agencies to adhere to healthy behaviors due to the chance of unintended pregnancy. Our objectives are to understand knowledge, confidence, and reported behaviors that promote safe water drinking and prevent lead exposure among women of reproductive age.

Methods

A survey among females of reproductive age from the University of Michigan - Flint was administered. A total of 83 females who wished to become pregnant one day participated.

Results

Low levels of knowledge, confidence, and reported preventative health behaviors related to safe water drinking and lead exposure prevention existed. Specifically, 71.1% of respondents (59 of 83) were not at all or were somewhat confident in their ability to choose an appropriate lead water filter. Most participants rated their knowledge on how to decrease exposure to lead during pregnancy as poor/fair. No statistically significant differences were detected between respondents residing inside and outside of the city of Flint, Michigan for most variables assessed.

Conclusion

While the small sample size is a limitation, the study adds to an area of scarce research. Despite widespread media attention and resources directed toward reducing the negative health effects of lead exposure following the Flint Water Crisis, significant gaps in knowledge related to safe water drinking remain. Interventions are needed to increase knowledge, confidence, and healthy behaviors that promote safe water drinking among women of reproductive age.

Pubertal lead exposure affects ovary development, folliculogenesis and steroidogenesis by activation of IRE1α-JNK signaling pathway in rat

Epidemic studies showed that lead exposures are associated with various female reproductive dysfunctions, including infertility, miscarriage, preterm delivery, and early menopause. However, the mechanism involved is still unclear. In the current study, SD rats were exposed to lead at doses of 0, 5, 25, 50 or 250 mg/L through drinking water from postnatal day 21-56. Lead exposures did not affect the body weight or ovary weight. However, the puberty initiation (ages by which vagina opens and estrous cycle occurs) was significantly delayed by as many as 5.8 and 6.8 days respectively (P < 0.05). Also, lead exposures disrupted the estrous cycles, reduced the numbers of primordial and primary follicles and increased the number of atretic follicles by adult. Furthermore, for the highest does group, serum levels of progesterone and testosterone decreased by 80.2% (P < 0.01) and 49.9% (P < 0.05) respectively, while estradiol level increased by 69.8% (P < 0.01). Western blot analyses indicated that lead exposures specifically down-regulated the expressions of steroidogenic protein STAR, CYP17A1, and HSD3B1, while up-regulated FSHR and CYP19A1. Also, the exposure stimulated the endoplasmic reticulum stress (ERS)-related IRE1α-JNK signaling pathway members. Such activation may also result in apoptosis since the death-signaling molecules CHOP and cleaved-CASP3 were up-regulated while BCL2 was down-regulated. In conclusion, lead exposure during juvenile and puberty significantly affected ovary development and functions. The effects may relate to ERS response since the 6 members related to the pathway were all consistently activated.

Serum lead levels and its association with overweight and obesity

BACKGROUND

Lead (Pb) exposure has been associated with cardiovascular diseases and metabolic syndrome, nevertheless its association with obesity, type 2 diabetes, and dyslipidemia markers has been little explored in Mexico. Therefore, we evaluated the association of serum Pb levels (Pb-S), with body mass index (BMI), fasting plasma glucose (FPG), total cholesterol (TC), and triglycerides (TG).

METHODS

A cross-sectional study was performed on 85 Mexican adults (57 women and 28 men). BMI was calculated, while FPG, TC, and TG were measured by the enzymatic colorimetric method. Total Pb-S levels were measured using inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

The study population was 20.3 ± 1.9 years old, showed an average of Pb-S of 0.0982 ± 0.068 μg dL^-1, and presented a frequency of overweight (OW) and obesity (OB) of 50.5% and 18.8%, respectively. Men had higher average FPG than women (Women= 83.930 ± 5.662 vs Men= 84.953 ± 6.495; p = 0.037). When we analyzed anthropometric and clinical variables, Pb-S and frequency of OW and OB were observed to increase within the categories of Pb-S tertiles (<0.001). The averages of Pb-S were 0.051 ± 0.035 µg dL^-1, 0.107 ± 0.067 µg dL^-1, and 0.151 ± 0.063 µg dL^-1 for individuals with normal weight (NW), OW, and OB, respectively. In addition, an analysis adjusted for age and sex shows Pb-S is positively associated with BMI (β = 2.76 ± 0.498, p = <0.001).

CONCLUSION

Our results evidence a significant association between Pb-S and the increase of BMI in Mexican adults and highlight the important health impact that may represent environmental Pb exposure.

Effects of maternal exposure to lead on secondary sex ratio in Japan: The Japan Environment and Children's Study

A decline in the proportion of male births (secondary sex ratio, SSR) has been seen in several countries including Japan in recent years. Although previous studies have reported that the SSR is affected by exposure to chemical substances such as dioxins and polychlorinated biphenyls, as well as heavy metals such as methylmercury, the effects of lead exposure on the SSR have been little studied. The aim of this study was to determine the association between maternal lead exposure and SSR. In a large-scale nationwide birth cohort study, maternal blood lead level (BLL) was determined using whole blood from the second or third trimester of pregnancy. The association between SSR and maternal BLL was estimated using multivariable logistic models. Binomial distribution was applied to examine the differences in SSR by dividing the participants into five groups based on BLL. The primary outcome was SSR, and the child sex was obtained from the medical record transcripts. Of 104,062 fetal records, 85,171 were examined for analysis. The median maternal BLL was 5.85 ng/g (5th-95th percentile 3.45-10.6 ng/g). The overall proportion of males among participating infants was 0.512. In logistic regression models adjusted for covariates, the analysis revealed an increased odds ratio for SSR with higher blood lead concentrations [Group 2: adjusted OR 1.082, 95% confidence interval 1.037 to 1.129, Group 3: 1.122, 1.074 to 1.171, Group 4: 1.214, 1.163 to 1.268, Group 5: 1.279, 1.224 to 1.336]. Compared to the general birth probability in Japan, the group with low BLL had a lower SSR and the group with high BLL had a higher SSR. Higher maternal lead exposures during pregnancy were associated with increased SSR. Further investigations including assessment of paternal lead exposure are necessary to understand the association between lead exposure and SSR.

Predictors of toxic metal exposures among US women of reproductive age

BACKGROUND

Arsenic, cadmium, lead, and mercury are ubiquitous toxicants that may be especially harmful to unborn children. We therefore sought to identify temporal trends and predictors of toxic metal biomarkers among US women of reproductive age, including those who were pregnant and/or breastfeeding.

METHODS

Interviews and examinations were performed among a representative sample of women, aged 20-44 years, as part of the 2003-2014 National Health and Nutrition Examination Surveys. A range of sociodemographic, lifestyle, and dietary factors were evaluated as predictors of urinary inorganic arsenic, urinary cadmium, blood mercury, and blood lead concentrations.

RESULTS

Levels of all four toxic metal biomarkers declined during the study period. Older age, racial/ethnic minorities, and a birthplace outside of the US were independently associated with higher toxic metal concentrations. Associations were similar for women who were pregnant or breastfeeding and those who were not.

CONCLUSION

US women of reproductive age were exposed to lower levels of toxic metals in 2013-2014 compared to 2003-2004. However, because the long-term health effects of early life exposures are unclear, public health efforts to address toxic metals should pay particular attention to older, nonwhite, and foreign-born women if they are pregnant or planning to become pregnant.

Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) Project

PURPOSE

The Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) Project is a mother-child pregnancy and birth cohort originally initiated in the mid-1990s to explore: (1) whether enhanced mobilisation of lead from maternal bone stores during pregnancy poses a risk to fetal and subsequent offspring neurodevelopment; and (2) whether maternal calcium supplementation during pregnancy and lactation can suppress bone lead mobilisation and mitigate the adverse effects of lead exposure on offspring health and development. Through utilisation of carefully archived biospecimens to measure other prenatal exposures, banking of DNA and rigorous measurement of a diverse array of outcomes, ELEMENT has since evolved into a major resource for research on early life exposures and developmental outcomes.

PARTICIPANTS

n=1643 mother-child pairs sequentially recruited (between 1994 and 2003) during pregnancy or at delivery from maternity hospitals in Mexico City, Mexico.

FINDINGS TO DATE

Maternal bone (eg, patella, tibia) is an endogenous source for fetal lead exposure due to mobilisation of stored lead into circulation during pregnancy and lactation, leading to increased risk of miscarriage, low birth weight and smaller head circumference, and transfer of lead into breastmilk. Daily supplementation with 1200 mg of elemental calcium during pregnancy and lactation reduces lead resorption from maternal bone and thereby, levels of circulating lead. Beyond perinatal outcomes, early life exposure to lead is associated with neurocognitive deficits, behavioural disorders, higher blood pressure and lower weight in offspring during childhood. Some of these relationships were modified by dietary factors; genetic polymorphisms specific for iron, folate and lipid metabolism; and timing of exposure. Research has also expanded to include findings published on other toxicants such as those associated with personal care products and plastics (eg, phthalates, bisphenol A), other metals (eg, mercury, manganese, cadmium), pesticides (organophosphates) and fluoride; other biomarkers (eg, toxicant levels in plasma, hair and teeth); other outcomes (eg, sexual maturation, metabolic syndrome, dental caries); and identification of novel mechanisms via epigenetic and metabolomics profiling.

FUTURE PLANS

As the ELEMENT mothers and children age, we plan to (1) continue studying the long-term consequences of toxicant exposure during the perinatal period on adolescent and young adult outcomes as well as outcomes related to the original ELEMENT mothers, such as their metabolic and bone health during perimenopause; and (2) follow the third generation of participants (children of the children) to study intergenerational effects of in utero exposures.

TRIAL REGISTRATION NUMBER

NCT00558623.

Blood Lead Levels in Women of Child-Bearing Age in Sub-Saharan Africa: A Systematic Review

This paper reported available studies on blood lead level of childbearing age in Sub-Saharan African women. PubMed and Google scholar databases were searched for original articles reporting blood lead levels of women of childbearing age in Sub-Saharan Africa. Searches were not limited to year of study but limited to studies published in English Language. Data were extracted and synthesized by estimating the weighted mean of the reported blood lead levels. Fifteen papers fulfilled the inclusion criteria. Mean blood lead levels of women in the studies ranged from 0.83 to 99 μg/dl. The overall weighted mean of blood lead levels was 24.73 μg/dl. The weighted mean from analyses of data on blood lead levels of pregnant women alone was 26.24 μg/dl. Identified sources of lead exposure included lead mine, informal lead-acid battery recycling, leaded gasoline and piped water. Elevated BLLs were associated with incidence of preeclampsia, hypertension, and malaria. Important contributing factors for elevated blood lead levels (BLL) in these women include poverty, high environmental lead burden, low awareness on lead exposure hazards and lack of regulation for lead in consumer products. BLLs of women of childbearing age in SSA are unacceptably high. There is need therefore, for aggressive programs to address lead exposure in this population.

Association between Blood Lead Levels and Delta-Aminolevulinic Acid Dehydratase in Pregnant Women

Blood lead levels (BLLs) and delta-aminolevulinic acid dehydratase (ALAD) activity are considered biomarkers of lead exposure and lead toxicity, respectively. The present study was designed to investigate the association between BLLs and ALAD activity in pregnant women from Durango, Mexico. A total of 633 pregnant women aged 13–43 years participated in this study. Blood lead was measured by a graphite furnace atomic absorption spectrometer. ALAD activity was measured spectrophotometrically. Mean blood lead was 2.09 ± 2.34 µg/dL; and 26 women (4.1%) crossed the Centers for Disease Control (CDC) recommended level of 5 µg/dL. ALAD activity was significantly lower in women with levels of lead ≥5 µg/dL compared to those with BLLs < 5 µg/dL (p = 0.002). To reduce the influence of extreme values on the statistical analysis, BLLs were analyzed by quartiles. A significant negative correlation between blood lead and ALAD activity was observed in the fourth quartile of BLLs (r = −0.113; p < 0.01). Among women with blood lead concentrations ≥2.2 µg/dL ALAD activity was negatively correlated with BLLs (r = −0.413; p < 0.01). Multiple linear regression demonstrated that inhibition of ALAD in pregnant women may occur at levels of lead in blood above 2.2 µg/dL.

Low-level environmental metals and metalloids and incident pregnancy loss

Environmental exposure to metals and metalloids is associated with pregnancy loss in some but not all studies. We assessed arsenic, cadmium, mercury, and lead concentrations in 501 couples upon trying for pregnancy and followed them throughout pregnancy to estimate the risk of incident pregnancy loss. Using Cox proportional hazard models, we estimated hazard ratios (HR) and 95% confidence intervals (CIs) for pregnancy loss after covariate adjustment for each partner modeled individually then we jointly modeled both partners' concentrations. Incidence of pregnancy loss was 28%. In individual partner models, the highest adjusted HRs were observed for female and male blood cadmium (HR=1.08; CI 0.81, 1.44; HR=1.09; 95% CI 0.84, 1.41, respectively). In couple based models, neither partner's blood cadmium concentrations were associated with loss (HR=1.01; 95% CI 0.75, 1.37; HR=0.92; CI 0.68, 1.25, respectively). We observed no evidence of a significant relation between metal(loids) at these environmentally relevant concentrations and pregnancy loss.

The relationship between blood lead levels and occupational exposure in a pregnant population

Background

Pregnant women exposed to lead are at risk of suffering reproductive damages, such as miscarriage, preeclampsia, premature delivery and low birth weight. Despite that the workplace offers the greatest potential for lead exposure, there is relatively little information about occupational exposure to lead during pregnancy. This study aims to assess the association between blood lead levels and occupational exposure in pregnant women from Durango, Mexico.

Methods

A cross-sectional study was carried out in a population of 299 pregnant women. Blood lead was measured in 31 women who worked in jobs where lead is used (exposed group) and 268 who did not work in those places (control group). Chi-square test was applied to compare exposed and control groups with regard to blood lead levels. Odds ratio (OR) and 95% confidence intervals (CI) were calculated. Multivariable regression analysis was applied to determine significant predictors of blood lead concentrations in the exposed group.

Results

Exposed women had higher blood lead levels than those in the control group (4.00 ± 4.08 μg/dL vs 2.65 ± 1.75 μg/dL, p = 0.002). Furthermore, women in the exposed group had 3.82 times higher probability of having blood lead levels ≥ 5 μg/dL than those in the control group. Wearing of special workwear, changing clothes after work, living near a painting store, printing office, junkyard or rubbish dump, and washing the workwear together with other clothes resulted as significant predictors of elevated blood lead levels in the exposed group.

Conclusions

Pregnant working women may be at risk of lead poisoning because of occupational and environmental exposure. The risk increases if they do not improve the use of protective equipment and their personal hygiene.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3902-3) contains supplementary material, which is available to authorized users.

Maternal lead exposure and risk of congenital heart defects occurrence in offspring

Maternal lead exposure may be harmful to fetal development. However, sufficient evidence was lacked about the risk on cardiac development in offspring. To explore the association between maternal lead exposure and risks of congenital heart defects (CHDs) occurrence in fetuses, a case-control study was adopted during pregnant women making antenatal examinations. The maternal hair lead levels were measured by using inductively coupled plasma mass spectrometry (ICP-MS), and logistic regression analysis was used to calculate the odds ratio (OR). Three hundred and sixteen cases and 348 controls were eligible to the study. The median level of lead in maternal hair of case (0.670ng/mg) was significantly higher (AOR 3.07, 95% CI 2.00-4.72) than that of the control (0.461ng/mg), including the CHD cases with or without extracardiac malformations (AOR 3.55, 2.94, respectively). Maternal lead exposure is associated with the risk of some subtypes of CHDs occurrence in offspring. The potential dose-response relationship is also presented.

Early pregnancy blood lead and spontaneous abortion

Although evidence tends to suggest that high levels of lead exposure increase the risk of spontaneous abortion, we do not yet know whether moderate- to low-level exposure elevates risk. Among 351 women (aged 16 to 35 years, with single pregnancies) who were registered for a longitudinal study, 15 (4.3%) women experienced spontaneous abortion after the 12th week of gestation and before the 20th week. We collected participants' blood samples during the first trimester of pregnancy (8-12 weeks) for lead measurement by inductively coupled plasma-mass spectrometry. Mean ± standard deviation of blood lead was 3.8 ± 2.0 μg/dl (range 1.0-20.5 μg/dl) with a geometric mean of 3.5 μg/dl. Mean blood lead concentrations did not differ significantly between spontaneous abortion cases and ongoing pregnancies (3.51 ± 1.42 and 3.83 ± 1.99 μg/dl, respectively). The findings suggest that in apparently healthy women, low blood lead levels (mean < 5 μg/dl) measured in early pregnancy may not be a risk factor for spontaneous abortion.

Lead exposure in female workers who are pregnant or of childbearing age

In adults, high-level lead exposure often occurs in the lead-related industries. Acute lead poisoning has become rare, but chronic exposure to low-level lead remains a public health issue. With recent advances in our understanding of lead toxicity at low-levels, researchers have shifted their focus to studying lead at concentrations below those currently recommended as 'acceptable' in worker protection. As gender plays an important role in the storage, biokinetics, and toxicity of lead, it seems inappropriate to extrapolate findings of lead exposure in men to women. Women's bones release lead more slowly to the bloodstream, so blood levels remain increased for a long time after cessation of high exposure, reflecting the endogenous source of the lead. Particularly in pregnant women, bone lead release could influence health in pregnancy and be extremely harmful to the rapidly growing and developing fetus. Accordingly, female workers of childbearing age should avoid excessive lead exposure. However, because studies of pregnant workers encounter many difficulties and inconveniences, sufficient research has not been conducted in this area. As an alternative, a group of non-occupationally exposed women, matched as well as possible for anthropometric and reproductive variables and with almost the same levels of blood lead, could be recruited for survey.

Perinatal lead and mercury exposure in Austria

OBJECTIVE

The heavy metals lead (Pb) and mercury (Hg) are ubiquitous environmental pollutants with high neurotoxic potential. We aimed to compare perinatal Pb and Hg concentrations and to explore the potential association between Pb and Hg exposure and newborn anthropometry.

STUDY DESIGN

Pregnant women were recruited in 2005 at the General Hospital Vienna for participation in this longitudinal study. Pb and Hg concentrations were measured in maternal blood and hair, placenta, cord blood, meconium, and breast milk of 53 mother-child pairs by CV-AAS, GF-AAS, and HPLC-CV-ICPMS. We conducted bivariate analyses and categorical regression analysis (CATREG) to evaluate the determinants of Pb and Hg exposure, and of infant anthropometry.

RESULTS

Median Pb and total Hg contents were low, i.e., 25 μg/L (maternal blood-Pb), 13 μg/L (cord blood-Pb), 0.7 μg/L (maternal blood-Hg), and 1.1 μg/L (cord blood-Hg). Hg levels in maternal and fetal tissues were frequently correlated (r>0.3, P<0.05, respectively). Regarding Pb, only maternal blood and cord blood concentrations correlated (P=0.043). Cord blood levels indicated higher Hg exposure but lower Pb exposure relative to maternal blood contents. Adjusted CATREG models indicated the significant predictors of birth length (placenta-Pb, gestational length, meconium-Pb), birth weight (placenta-Pb, gestational length, maternal blood-Pb), and head circumference (maternal education, maternal height). Besides one significant correlation between maternal hair Hg and birth length, the mercury levels were not associated with newborn anthropometry.

CONCLUSIONS

Our data implicate that different modes of action may exist for placentar transfer of Pb and Hg as well as that low Pb exposure levels can result in lower birth weight. The findings related to newborn anthropometry need to be confirmed by the examination of larger study groups. Further research is needed to clarify the mechanisms of Pb and Hg transfer via the placenta, and to explore how prenatal Pb exposure is related to intrauterine growth.

Time-dependent changes in lead and delta-aminolevulinic acid after subchronic lead exposure in rats

The time-dependent changes in lead (Pb) concentrations in major tissues, serum and urine, and the Pb biomarker delta-aminolevulinic acid (ALA) concentration in urine were studied in rats after sub-chronic Pb exposure. Female Sprague-Dawley (SD) rats were exposed to Pb in drinking water at concentrations of 100 ppm and 1000 ppm for 30 days. The Pb concentration in muscle, liver, kidney, plasma and urine, and the ALA concentration in urine were determined during exposure and every 7 days after exposure for 3 weeks. The muscle Pb concentration did not change post exposure. The liver Pb concentration increased 2.2 to 2.8 times (100 ppm group) and 3.9 to 7.4 times (1000 ppm group) during exposure, then decreased rapidly. Kidney Pb concentrations were 8.0 to 14.3 times (100 ppm group) and 13.8 to 28.5 times (1000 ppm group) higher than controls during exposure and decreased for 1 to 2 weeks post exposure. Plasma Pb concentrations were 1.2 to 3.3 times (100 ppm group) and 2.9 to 5.8 times (1000 ppm group) higher than control concentrations during exposure and decreased time-dependently in the 1000-ppm group after exposure. Urine Pb concentrations were 8.5 to 10.7 times (100 ppm group) and 30.4 to 51.1 times (1000 ppm group) higher than control concentrations during exposure and rapidly decreased after exposure, though concentrations remained up to 4 times higher than controls in the 1000 ppm exposure group. Urine ALA concentrations increased 1.7 to 2.6 and 7.1 to 32.7 times during exposure in the 100 ppm and 1000 ppm groups respectively, and remained elevated for 21 days post exposure. Our data support that urine Pb concentration is a useful marker for acute Pb exposure or post exposure. Urine ALA may be a predicator of biological response to Pb exposure.

Pilot study of association of anembryonic pregnancy with 55 elements in the urine, and serum level of folate, homocysteine and S-adenosylhomocysteine in Shanxi Province, China

OBJECTIVE

To estimate the association of anembryonic pregnancy with 55 elements, homocysteine, folate and S-adenosylhomocysteine in pregnant women.

METHODS

Thirty cases of anembryonic pregnancy were diagnosed using ultrasound scanning that showed an empty gestation sac with no embryo pole in the uterus. Additionally, thirty women with normal pregnancy were followed through the delivery a live and normal baby. The cases and controls were matched by age and week of gestation. Levels of 55 elements, homocysteine, folate and S-adenosylhomocysteine in women with anembryonic pregnancies were compared with those of the women experiencing normal pregnancies.

RESULTS

Women with anembryonic pregnancies had statistically significantly lower levels of folate and 10 elements including V, Ti, Li, Cd, Sr, Rb, P, Na, K, and B than did women experiencing normal pregnancies. However, they had higher homocysteine and Ge levels than did the controls.

CONCLUSIONS

The levels of multiple nutrients including folate, 11 elements and homocysteine may be associated with the risk of anembryonic pregnancy.

Biomonitoring of lead exposure-alternatives to blood

Lead ( Pb) is one of the most important models for biomonitoring of exposure, with the blood Pb concentration as a predominant choice in practice and in epidemiology. In this article the alternatives for biomarkers to blood are reviewed. This overview focuses on a number of different qualities that are of importance in the evaluation of a biomarker's usefulness and performance. The qualities scrutinized included: (1) analytical accuracy and precision; (2) cost; (3) practical issues; (4) what is reflected by the biomarker; (5) relationship to exposure; and (6) relationship to effects. Data indicate that the best biomarker in some circumstances may be blood, but bone or teeth (for past exposures), feces (for current gastrointestinal exposure), or urine (for organic Pb) are sometimes more useful. A striking feature is that no generally accepted biomarker of bioavailable Pb exists, though plasma, bone, teeth, urine, and hair have all been discussed. For one of the most used applications of blood Pb, monitoring of lead workers' exposure, blood has important shortcomings in that it shows a poor response to changes in exposure at high levels. The alternative of plasma has not been sufficiently evaluated to be considered an alternative in occupational health services, although previous analytical problems are basically overcome. Possibly, urine deserves also more attention. Almost all biomarkers lack systematic data on variation within and between individuals.