Lead exposure in pregnancy: a review of the literature and argument for routine prenatal screening

The role of geophagy and artisanal gold mining as risk factors for elevated blood lead levels in pregnant women in northwestern Tanzania

Neither artisanal and small-scale gold mining (ASGM) or geophagy practices have received substantial attention related to blood lead levels despite the well documented deleterious effects of lead. This cross-sectional analytical study aimed to document the risk of lead exposure from geophagy and mining-related occupational activities for pregnant women. The study recruited 1056 pregnant women (883 in an ASGM area and 173 in a non-ASGM area) between April 2015 -April 2017. Generalized Linear Model with an identity link function was used to model the association between blood lead levels (BLLs) and geophagy practices and involvement in gold mining. The prevalence of geophagy was 36.2% (95% CI: 33.6, 39.4%) and 6.3% engaged in mining as a primary occupation. Practicing geophagy increased BLLs by 22% (β = 1.22, 95% CI: 1.116, 1.309, p<0.0001). Living in a gold mining area increased BLLs by 33.4% (β = 1.334, 95% CI: 1.2, 1.483, p<0.0001). Having mining as a primary occupation increased BLLs by 1.3% β = 1.013, 95% CI: 0.872, 1.176, p = 0.869) even though the association was not statistically significant. Socioeconomic wealth quantile (β = 1.037, 95% CI: 1.021, 1.054, p<0.001) increased blood lead levels by 3.7%. Developing a comprehensive inventory capturing sources of community-level lead exposure is essential. Further, increasing public health campaigns and education are crucial to limit geophagy practices and to minimize work in gold mining activities during pregnancy.

Prevalence of Reproductive Health Issues among US Female Law Enforcement Officers

Reproductive health is a considerable concern among US female law enforcement officers (LEOs). Miscarriage and preterm birth rates are significantly higher in women firefighters than published US averages. Since law enforcement and firefighting share occupational conditions and practices, adverse birth outcomes were hypothesized to be greater in female law enforcement officers (LEOs) than the US averages. Occupational hazards may place pregnant LEOs at a higher risk for complicated pregnancies and adverse birth outcomes. This study quantified pregnancy outcomes in female LEOs using a cross-sectional survey and compared them to US averages and large prospective studies. The participants (N = 162, 72.2% aged 31-49, 85.2% Caucasian) averaged 2.5 ± 1.4 pregnancies. Stress (59.1%) and shiftwork (59.8%) were the most common reported exposures. Miscarriage and preterm birth rates were 19.1% and 16.4%, respectively. Miscarriages were significantly greater among participants compared to prospective studies [χ2 (1, N = 911,971) = 20.51, p < 0.001]. Female LEOs of childbearing age should receive education about potential reproductive health hazards and take precautions against them. Moreover, policymakers, human resources, and healthcare providers should understand how law enforcement work might affect maternal health.

Lead in drinking water and birth outcomes: A tale of two water treatment plants

The recent lead-in-water crisis in Newark has renewed concerns about the crisis being a widespread problem in the nation. Using data on the exact home addresses of pregnant women residing in the city combined with information on the spatial boundary separating areas within the city serviced by two water treatment plants, we exploit an exogenous change in water chemistry that resulted in lead leaching into the tap water of one plant's service area, but not the other's, to identify a causal effect of prenatal lead exposure on fetal health. We find robust evidence of adverse health impacts, which has important policy implications in light of the substantial number of lead water pipes that remain in use as part of our aging infrastructure and the cost-benefit calculus of lead abatement interventions.

What to Expect When Expecting in Lab: A Review of Unique Risks and Resources for Pregnant Researchers in the Chemical Laboratory

Pregnancy presents a unique risk to chemical researchers due to their occupational exposures to chemical, equipment, and physical hazards in chemical research laboratories across science, engineering, and technology disciplines. Understanding “risk” as a function of hazard, exposure, and vulnerability, this review aims to critically examine the state of the science for the risks and associated recommendations (or lack thereof) for pregnant researchers in chemical laboratories (labs). Commonly encountered hazards for pregnant lab workers include chemical hazards (organic solvents, heavy metals, engineered nanomaterials, and endocrine disruptors), radiation hazards (ionizing radiation producing equipment and materials and nonionizing radiation producing equipment), and other hazards related to the lab environment (excessive noise, excessive heat, psychosocial stress, strenuous physical work, and/or abnormal working hours). Lab relevant doses and routes of exposure in the chemical lab environment along with literature and governmental recommendations or resources for exposure mitigation are critically assessed. The specific windows of vulnerability based on stage of pregnancy are described for each hazard, if available. Finally, policy gaps for further scientific research are detailed to enhance future guidance to protect pregnant lab workers.

Crude oil and public health issues in Niger Delta, Nigeria: Much ado about the inevitable

The importance of crude oil has come at a great cost. In many developing economies of the world, it can be described as the bitter-sweet crude for its double-edged impacts on the welfare, wellness and wellness of the people. Agitations and restiveness remain characteristic features of Niger Delta following claims of exploitation and neglect of the local population by the multinationals. Literature on the environmental and public health impacts of crude oil was searched from relevant databases such as google scholar, Science Direct, Scopus and PubMed. This paper is a translational scientific and toxicological insight on what should be done by the major players rather than casting unending aspersions. Since living near oil spills and crude oil production sites is an environmental stressor occasioned by exposure to both chemical pollutants and physical menace that are all detrimental to health, cumulative risk assessment CRA is proposed as a viable approach for a comprehensive understanding of the size of this problem. Multinational oil companies should support development of Environmental Medicine Research which will in turn generate data on both how to harness the natural resources to combat the public health issues associated with oil exploration and the mitigation and remediation of the environment. This endeavor will create a waste-to-wealth program that will pacify the restiveness in oil exploring communities. It will be interesting to know that in the same environment that breeds the elephant-in-the-parlor lies the natural antidotes to check-mate the public health malady.

(Ascorb)ing Pb Neurotoxicity in the Developing Brain

Lead (Pb) neurotoxicity is a major concern, particularly in children. Developmental exposure to Pb can alter neurodevelopmental trajectory and has permanent neuropathological consequences, including an increased vulnerability to further stressors. Ascorbic acid is among most researched antioxidant nutrients and has a special role in maintaining redox homeostasis in physiological and physio-pathological brain states. Furthermore, because of its capacity to chelate metal ions, ascorbic acid may particularly serve as a potent therapeutic agent in Pb poisoning. The present review first discusses the major consequences of Pb exposure in children and then proceeds to present evidence from human and animal studies for ascorbic acid as an efficient ameliorative supplemental nutrient in Pb poisoning, with a particular focus on developmental Pb neurotoxicity. In doing so, it is hoped that there is a revitalization for further research on understanding the brain functions of this essential, safe, and readily available vitamin in physiological states, as well to justify and establish it as an effective neuroprotective and modulatory factor in the pathologies of the nervous system, including developmental neuropathologies.

Assessment of a Screening Questionnaire to Identify Exposure to Lead in Pregnant Women

Lead readily crosses the placenta and displays adverse effects on birth outcomes and neurodevelopment. Systematic identification of the risk of exposure during pregnancy is essential but rarely performed, probably due to hospital staff’s workload and their lack of awareness. We aimed to evaluate the relevance of a questionnaire to screen pregnant women for lead exposure. A cross-sectional, multicentre study was carried out on a population of 792 pregnant women from February 2018 to May 2020. A total of 596 women had a blood lead test: 68.5% had blood lead levels below 10 μg/L. The estimated prevalence above 25 µg/L was 4% (95% confidence interval (CI) [2.6–5.9]) and 1.3% had levels above 50 µg/L (95% CI [0.6–2.6]). Multivariate analysis showed that three risk factors significantly increased the probability of blood lead levels above 25 µg/L: the use of traditional cosmetics (adjusted odds ratio [aOR]: 3.90; 95% CI [1.65–9.21]; p = 0.002), degraded old housing (aOR: 2.67; 95% CI [1.19–6.038]; p = 0.018), and (marginally) eating bread more than twice a day (aOR: 2.40; 95% CI [0.96–6.11]; p = 0.060). Our study reveals that a three-question tool can be used to quickly screen for the risk of lead exposure in our population and to trigger lead blood tests and special vigilance during pregnancy follow-up.

Periconceptional and prenatal exposure to metal mixtures in relation to behavioral development at 3 years of age

Supplemental Digital Content is available in the text.

Behavioral effects of prenatal exposure to mixtures of essential and toxic metals are incompletely understood.

Maternal exposure to air pollution and the risk of small for gestational age in offspring: A population-based study in Taiwan

BACKGROUND

Exposure to air pollution has been associated with a wide range of adverse health effects; however, few studies addressed the relationship between ambient particulate matter as well as the compositions in particulate matter such as lead and the risk of small for gestational age (SGA) in offspring. The aim of this study is to investigate the effect of maternal exposure to criteria air pollutants and the lead in total suspended particulate matter during pregnancy on SGA births in Taiwan.

METHODS

This population study consisted of 322,513 singleton live births in Taiwan between 1996 and 2002. Daytime (7 AM-7 PM) exposure to particulate matter ≤10 μm (PM₁₀), carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃), and monthly exposure to lead in total suspended particles (TSP) during each trimester were estimated. Generalized additive model (GAM) was used to assess the association between maternal exposure to particulate air pollutants and SGA births, taking into account potential confounders and gaseous air pollutants.

RESULTS

We found significant association between the highest quartile (≥75th) of maternal PM₁₀ exposure and SGA and demonstrated a significant exposure-response relationship. Furthermore, the highest quartile (≥75th) of maternal lead exposure was also associated with SGA during the second and third trimester of pregnancy, and there was a significant exposure-response relationship between maternal lead exposure and SGA during pregnancy.

CONCLUSION

Maternal exposure to PM₁₀ and lead in total suspended particulate matter during pregnancy was associated with an increased risk of SGA in offspring.

Current trends of blood lead levels, distribution patterns and exposure variations among household members in Kabwe, Zambia

Childhood lead (Pb) poisoning has devastating effects on neurodevelopment and causes overt clinical signs including convulsions and coma. Health effects including hypertension and various reproductive problems have been reported in adults. Historical Pb mining in Zambia's Kabwe town left a legacy of environmental pollution and childhood Pb poisoning. The current study aimed at establishing the extent of Pb poisoning and exposure differences among family members in Kabwe as well as determining populations at risk and identify children eligible for chelation therapy. Blood samples were collected in July and August 2017 from 1190 household members and Pb was measured using a portable LeadCare-II analyser. Participants included 291 younger children (3-months to 3-years-old), 271 older children (4-9-years-old), 412 mothers and 216 fathers from 13 townships with diverse levels of Pb contamination. The Blood Lead Levels (BLL) ranged from 1.65 to 162  μg/dL, with residents from Kasanda (mean 45.7  μg/dL) recording the highest BLL while Hamududu residents recorded the lowest (mean 3.3  μg/dL). Of the total number of children sampled (n = 562), 23% exceeded the 45  μg/dL, the threshold required for chelation therapy. A few children (5) exceeded the 100  μg/dL whereas none of the parents exceeded the 100  μg/dL value. Children had higher BLL than parents, with peak BLL-recorded at the age of 2-years-old. Lead exposure differences in Kabwe were attributed to distance and direction from the mine, with younger children at highest risk. Exposure levels in parents were equally alarming. For prompt diagnosis and treatment, a portable point-of-care devise such as a LeadCare-II would be preferable in Kabwe.

Oral exposure to lead for Japanese children and pregnant women, estimated using duplicate food portions and house dust analyses

BACKGROUND

Lead is a toxic metal abundant in the environment. Consumption of food contaminated at low levels of lead, especially by small children and pregnant women, raises a health concern.

METHODS

Duplicated food portions and drinking water were collected over 3 days from 88 children and 87 pregnant women in Shimotsuke, Tochigi, Japan. Participants were recruited in this study between January 2014 and October 2015. Dust was also collected from their homes. Lead concentrations were measured and consequent oral lead exposure levels were estimated for this population at high risk to environmental toxicants. Lead concentrations of peripheral and cord blood, taken from children and pregnant women, and were also analyzed.

RESULTS

Lead concentrations in food, drinking water, and house dust were low in general. Oral lead exposure to lead was higher for children (Mean ± SEM; 5.21 ± 0.30 μg/kg BW/week) than in pregnant women (1.47 ± 0.13 μg/kg BW/week). Food and house dust were main sources of lead contamination, but the contribution of house dust widely varied. Means ± SEM of peripheral and cord blood lead concentrations were 0.69 ± 0.04 μg/dL and 0.54 ± 0.05 μg/dL, respectively for pregnant women and 1.30 ± 0.07 μg/dL (peripheral only) in children. We detect no correlation between smoking situations and blood lead concentration in pregnant women.

CONCLUSION

We conclude that oral lead exposure levels for Japanese children and pregnant women were generally low, with higher concentrations and exposure for children than for pregnant women. More efforts are necessary to clarify the sources of lead contamination and reduce lead exposure of the population at high risk even in Japan.

Fetal exposure to mercury and lead from intrauterine blood transfusions

BACKGROUND

Mercury (Hg) and lead (Pb) exposure during childhood is associated with irreversible neurodevelopmental effects. Fetal exposure to Hg and Pb from intrauterine blood transfusion (IUBT) has not been reported.

METHODS

Fetal exposure was estimated based on transfusion volume and metal concentration in donor packed red blood cell (PRBCs). As biomarkers to quantify prenatal exposure are unknown, Hg and Pb in donor PRBCs were compared to estimated intravenous (IV) RfDs based on gastrointestinal absorption.

RESULTS

Three pregnant women received 8 single-donor IUBTs with volumes ranging from 19 to 120 mL/kg. Hg and Pb were present in all donor PRBC units. In all, 1/8 IUBT resulted in Hg dose five times higher than the estimated IV RfD. Median Pb dose in one fetus who received 5 single-donor IUBTs between 20-32 weeks gestation was 3.4 μg/kg (range 0.5-7.9 μg/kg). One donor unit contained 12.9 μg/dL of Pb, resulting in a fetal dose of 7.9 μg/kg, 40 times higher than the estimated IV RfD at 20 weeks gestation.

CONCLUSION

This is the first study documenting inadvertent exposure to Hg and Pb from IUBT and quantifying the magnitude of exposure. Screening of donor blood is warranted to prevent toxic effects from Hg and Pb to the developing fetus.

Neurotoxicity of low-level lead exposure: History, mechanisms of action, and behavioral effects in humans and preclinical models

Lead is a neurotoxin that produces long-term, perhaps irreversible, effects on health and well-being. This article summarizes clinical and preclinical studies that have employed a variety of research techniques to examine the neurotoxic effects of low levels of lead exposure. A historical perspective is presented, followed by an overview of studies that examined behavioral and cognitive outcomes. In addition, a short summary of potential mechanisms of action is provided with a focus on calcium-dependent processes. The current level of concern, or reference level, set by the CDC is 5 μg/dL of lead in blood and a revision to 3.5 μg/dL has been suggested. However, levels of lead below 3 μg/dL have been shown to produce diminished cognitive function and maladaptive behavior in humans and animal models. Because much of the research has focused on higher concentrations of lead, work on low concentrations is needed to better understand the neurobehavioral effects and mechanisms of action of this neurotoxic metal.

Lead and Arsenic in Shed Deciduous Teeth of Children Living Near a Lead-Acid Battery Smelter

Lead (Pb) is a potent neurotoxicant with no safe level of exposure. Elevated levels of Pb and arsenic (As) are found in the air and soil near facilities that recycle lead-acid batteries in the United States. In urban Los Angeles County, California, a facility processed ∼11 million batteries per year and operated for decades without proper environmental review. Measuring Pb and As in shed deciduous teeth is a promising technique to assess prenatal and early life exposure. In this pilot study coined the "Truth Fairy" Project, 50 shed deciduous teeth from 43 children living their entire lives within 2 miles of the smelter were analyzed to understand retrospective exposure to toxic metals using a community-driven research approach. Concentrations of Pb and As in teeth were assessed using laser-ablation-inductively coupled plasma-mass spectrometry. Soil Pb concentrations were determined using spatial kriging of surface soil measurements. The mean prenatal calcium normalized Pb levels in teeth samples (reported as a ratio 208Pb:43Ca) was 4.104 × 10-4 (SD 4.123 × 10-4), and the mean postnatal 208Pb:43Ca level was 4.109 × 10-4 (SD 3.369 × 10-4). Adjusted for maternal education and batch, we observe positive significant relationship between prenatal teeth Pb per 100 ppm increase in soil Pb (β = 3.48, 95% CI 1.11, 5.86). The Truth Fairy study suggests prenatal and early life exposure to toxic metals is associated with legacy soil contamination in an urban community near a smelter.

Exposure profile of mercury, lead, cadmium, arsenic, antimony, copper, selenium and zinc in maternal blood, cord blood and placenta: the Tohoku Study of Child Development in Japan

BACKGROUND

The effects of prenatal exposure to toxic elements on birth outcomes and child development have been an area of concern. This study aimed to assess the profile of prenatal exposure to toxic elements, arsenic (As), bismuth (Bi), cadmium (Cd), mercury (total mercury (THg), methylmercury (MHg), inorganic mercury (IHg)), lead (Pb), antimony (Sb) and tin (Sn), and essential trace elements, copper (Cu), selenium (Se) and zinc (Zn), using the maternal blood, cord blood and placenta in the Tohoku Study of Child Development of Japan (N = 594-650).

METHODS

Inductively coupled plasma mass spectrometry was used to determine the concentrations of these elements (except mercury). Levels of THg and MeHg were measured using cold vapour atomic absorption spectrophotometry and a gas chromatograph-electron capture detector, respectively.

RESULTS

Median concentrations (25th-75th) of As, Cd, Pb, Sb, Sn and THg in the maternal blood were 4.06 (2.68-6.81), 1.18 (0.74-1.79), 10.8 (8.65-13.5), 0.2 (0.06-0.40) and 0.2 (0.1-0.38) ng mL^-1 and 5.42 (3.89-7.59) ng g^-1, respectively. Median concentrations (25th-75th) of As, Cd, Pb, Sb, Sn and THg in the cord blood were 3.68 (2.58-5.25), 0.53 (0.10-1.25), 9.89 (8.02-12.5), 0.39 (0.06-0.92) and 0.2 (0.2-0.38) ng mL^-1 and 9.96 (7.05-13.8) ng g^-1, respectively.

CONCLUSIONS

THg and Sb levels in the cord blood were twofold higher than those in the maternal blood. Cord blood to maternal blood ratios for As, Cd and Sb widely varied between individuals. To understand the effects of prenatal exposure, further research regarding the variations of placental transfer of elements is necessary.

Amelioration of Prenatal Lead-Induced Learning and Memory Impairments by Methanolic Extract of Zataria Multiflora in Male Rats

Introduction

The current study aimed at evaluating the effects of Zataria Multiflora (ZM) on learning and memory of adult male offspring rats with prenatal lead-exposure.

Methods

Pregnant rats in the case group received tap water containing 0.2% lead acetate throughout the gestation period. Control rats had free access to lead-free tap water. Two male offspring (two-month-old, weighing 180-200 g) from each mother were randomly selected and treated with either Z. Multiflora (50, 200, 400, and 800 mg/kg/Intraperitoneally (I.P)/20 day) or saline. Spatial memory of the control, saline, and ZM-treated rats was evaluated by a training trial and probe test using Morris water maze (6-8 rat/group).

Results

The obtained results showed memory deficits including increased escape latency, and a greater traveled distance, as well as decrements in the frequency of crossings into target quadrants in prenatally lead-exposed male offspring compared with the controls. ZM treatment (200 mg/kg/i.p) ameliorated the memory deficits in male offspring by increasing the time spent and traveled distance in the trigger zone (P<0.01 vs. saline).There was no significant difference in swimming speed between the groups.

Conclusion

The results showed memory deficits in prenatally lead-exposed male offspring. ZM treatment (especially 200 mg/kg) had beneficial effects on cognitive behavior and was indicated as the improvement of lead-induced memory deficits in prenatally lead-exposed male rats. The exact mechanism(s) is not determined yet, but it could be mediated through the anticholinesterase and antioxidant effects and also alterations in Central Nervous System (CNS) and neurotransmission in the central nervous system.

The State of Public Health Lead Policies: Implications for Urban Health Inequities and Recommendations for Health Equity

Although lead has been removed from paint and gasoline sold in the U.S., lead exposures persist, with communities of color and residents in urban and low-income areas at greatest risk for exposure. The persistence of and inequities in lead exposures raise questions about the scope and implementation of policies that address lead as a public health concern. To understand the multi-level nature of lead policies, this paper and case study reviews lead policies at the national level, for the state of California, and for Santa Ana, CA, a dense urban city in Southern California. Through a community-academic partnership process, this analysis examines lead exposure pathways represented, the level of intervention (e.g., prevention, remediation), and whether policies address health inequities. Results indicate that most national and state policies focus on establishing hazardous lead exposure levels in settings and consumer products, disclosing lead hazards, and remediating lead paint. Several policies focus on mitigating exposures rather than primary prevention. The persistence of lead exposures indicates the need to identify sustainable solutions to prevent lead exposures in the first place. We close with recommendations to reduce lead exposures across the life course, consider multiple lead exposure pathways, and reduce and eliminate health inequities related to lead.

Amelioration of Prenatal Lead-Induced Learning and Memory Impairments by Methanolic Extract of Zataria Multiflora in Male Rats

Introduction:

The current study aimed at evaluating the effects of Zataria Multiflora (ZM) on learning and memory of adult male offspring rats with prenatal lead-exposure.

Methods:

Pregnant rats in the case group received tap water containing 0.2% lead acetate throughout the gestation period. Control rats had free access to lead-free tap water. Two male offspring (two-month-old, weighing 180–200 g) from each mother were randomly selected and treated with either Z. Multiflora (50, 200, 400, and 800 mg/kg/Intraperitoneally (I.P)/20 day) or saline. Spatial memory of the control, saline, and ZM-treated rats was evaluated by a training trial and probe test using Morris water maze (6–8 rat/group).

Results:

The obtained results showed memory deficits including increased escape latency, and a greater traveled distance, as well as decrements in the frequency of crossings into target quadrants in prenatally lead-exposed male offspring compared with the controls. ZM treatment (200 mg/kg/i.p) ameliorated the memory deficits in male offspring by increasing the time spent and traveled distance in the trigger zone (P<0.01 vs. saline).There was no significant difference in swimming speed between the groups.

Conclusion:

The results showed memory deficits in prenatally lead-exposed male offspring. ZM treatment (especially 200 mg/kg) had beneficial effects on cognitive behavior and was indicated as the improvement of lead-induced memory deficits in prenatally lead-exposed male rats. The exact mechanism(s) is not determined yet, but it could be mediated through the anticholinesterase and antioxidant effects and also alterations in Central Nervous System (CNS) and neurotransmission in the central nervous system.

Investigation of occupational exposure to lead and its relation with blood lead levels in electrical solderers

Occupational exposure to lead compounds can cause headache, nausea, encephalopathy, anemia, chronic muscle pain, and saturnism. Exposure to lead in women can affect fertility, and cause abortion or low IQ in the offspring. The aim of this study was to investigate occupational exposure to lead and its relation with blood lead levels in female electrical parts solderers. This cross-sectional (descriptive and analytical) study was carried out on 40 female solderers, working in two electrical parts manufacturing factories in Neyshabur city in 2017-2018. Occupational exposure to lead was determined by the OSHA 121 method, and the NIOSH 8003 method was used to determine the concentration of lead in blood. Lead in blood and air samples were determined by using a flame atomic absorption analyzer. Blood was measured using a Cell Dyn Hematology device. Data were analyzed using STATA 15. The mean age of the solderers was 35.42 ± 6.80 years, and their average work experience was 7.85 ± 5.60 years. Mean occupational exposure to lead was 0.09 ± 0.01 mg/m³, and the mean levels of lead in the blood of solderers were 10.59 ± 3.25 μg/dL. The mean of red blood cells (RBC) was 4.88 mil/uL, white blood cells (WBC) = 8.53 Tho/uL, hemoglobin = 14.02 g/dL, and hematocrit = 42.38%. There was a significant correlation between the concentrations of lead in air and the level of lead in workers' blood (p = 0.012, r = 0.31). The level of lead in the workers' respiratory region (β = 0.36, p = 0.033), body mass index (β = 0.25, p = 0.028), and the season of the year (β = 0.21, p = 0.019) were the strongest factors affecting blood lead levels. There was a significant relation between lead in workers' air and their blood, although all blood indices were in normal range. Using lead-free alloys and local ventilation systems, and reducing exposure times are recommended to decrease exposure to lead among solderers.

Effect of developmental lead exposure on neurogenesis and cortical neuronal morphology in Wistar rats

Lead (Pb) is a neurotoxic heavy metal that largely affects the developing nervous system. The present study examined the temporal effect of perinatal Pb exposure on neurogenesis and cortical neuronal morphology. Wistar pregnant rats were exposed to 0.5% lead acetate throughout pregnancy and to postnatal day (PD) 28. Offspring were grouped as gestational day (GD) 18 and 21 and PD 7, 14, 21, and 28 in both control and experimental groups. Brain sections were processed for immunohistological staining with anti-proliferating cell nuclear antigen (PCNA) or glial fibrillary acidic protein (GFAP). Brains from 14, 21, and 28 PDs pups were processed for Golgi–Cox stain. Pb exposure significantly increased PCNA-positive nuclei in the ventricular and subventricular zones of the lateral ventricle at 18 and 21 GDs. Postnatally, the Pb-treated groups showed a significant decrease in PCNA-positivity and neuron density compared to control. This reduction was associated with an increase in damaged or apoptotic cell profiles in the experimental groups. At PD 21, there was a significant increase in GFAP immunoreactivity in Pb-exposed groups compared with control. Furthermore, the total apical and basal dendritic length of pyramidal neurons in layer 2–3 of the Golgi–Cox stained sensorimotor cortex was comparable in both control and Pb-exposed groups. Spine density per 10 µm was significantly increased at PD 14 and 21 on the apical dendrites but not basal dendrites of Pb-treated groups. In conclusion, developmental Pb exposure in rats induces a toxic effect on neurogenesis and on cortical neurons, which may be related to cognitive disabilities observed in children exposed to lead.

Ascorbic acid ameliorates lead-induced apoptosis in the cerebellar cortex of developing rats

We investigated the effects of the gestational administration of lead (Pb) and ascorbic acid on cerebellar development. Pregnant female rats were randomly assigned to the control, Pb, or Pb plus ascorbic acid (PA) groups; six offspring per cage were randomly selected for analysis. Compared to the control group, fewer Purkinje cells were observed in the Pb-exposed pups at postnatal day 21. However, co-administrating Pb and ascorbic acid inhibited the Pb-induced reduction in Purkinje cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining, which detected DNA fragmentation in the dying cells, showed more TUNEL-positive cells in the Pb group, while co-treatment with Pb and ascorbic acid mitigated the Pb-induced cellular degeneration. Using immunohistochemistry and immunoblotting, we additionally found that Pb exposure induced a rise in the apoptotic factor Bax in the cerebellum, while Pb plus ascorbic acid treatment ameliorated this Bax induction. Since, Pb competes with the iron in the cell and the accumulation of free iron triggers oxidative stress, we performed iron staining, which revealed that ascorbic acid prevented the Pb-induced rises in iron-reactive cells and iron-reactivity. The anti-oxidant enzyme manganese-dependent superoxide dismutase showed change patterns that were similar to those of iron in the cerebellum. Finally, the pups' blood Pb levels were highest in the Pb group but were reduced in the PA group. Our findings suggest that ascorbic acid effectively ameliorates Pb-induced apoptosis and oxidative stress in the cerebellum. The present results imply that ascorbic acid treatment during pregnancy may protect against Pb-mediated developmental impairments in the cerebellum.

Genome-wide gene by lead exposure interaction analysis identifies UNC5D as a candidate gene for neurodevelopment

BACKGROUND

Neurodevelopment is a complex process involving both genetic and environmental factors. Prenatal exposure to lead (Pb) has been associated with lower performance on neurodevelopmental tests. Adverse neurodevelopmental outcomes are more frequent and/or more severe when toxic exposures interact with genetic susceptibility.

METHODS

To explore possible loci associated with increased susceptibility to prenatal Pb exposure, we performed a genome-wide gene-environment interaction study (GWIS) in young children from Mexico (n = 390) and Bangladesh (n = 497). Prenatal Pb exposure was estimated by cord blood Pb concentration. Neurodevelopment was assessed using the Bayley Scales of Infant Development.

RESULTS

We identified a locus on chromosome 8, containing UNC5D, and demonstrated evidence of its genome-wide significance with mental composite scores (rs9642758, p _meta = 4.35 × 10^-6). Within this locus, the joint effects of two independent single nucleotide polymorphisms (SNPs, rs9642758 and rs10503970) had a p-value of 4.38 × 10^-9 for mental composite scores. Correlating GWIS results with in vitro transcriptomic profiles identified one common gene, SLC1A5, which is involved in synaptic function, neuronal development, and excitotoxicity. Further analysis revealed interconnected interactions that formed a large network of 52 genes enriched with oxidative stress genes and neurodevelopmental genes.

CONCLUSIONS

Our findings suggest that certain genetic polymorphisms within/near genes relevant to neurodevelopment might modify the toxic effects of Pb exposure via oxidative stress.

Infant and mother related outcomes from exposure to metals with endocrine disrupting properties during pregnancy

BACKGROUND

Endocrine-related adverse health effects from exposure to heavy metals such as lead, arsenic, cadmium, and mercury are yet to be adequately described. The purpose of this review was to gain insight into maternal exposure to heavy metals, and to identify potential endocrine-related adverse health effects in the mother and the infant.

METHODS

Relevant databases were searched for original research reports and a total of 46 articles were retained for scrutiny. Required data was extracted from these studies and their methodology was assessed.

RESULTS

Impaired fetal growth was observed from exposure to all endocrine disrupting metals, while exposure to lead and arsenic were associated with spontaneous abortion, stillbirth and neonatal deaths. Maternal exposure to arsenic was associated with impaired glucose tolerance in these mothers.

CONCLUSION

Impaired fetal growth, fetal loss, and neonatal deaths were significantly associated with heavy metals exposure during pregnancy; however, hypertension and gestational diabetes require further investigation.

Relationship between risk factors for infertility in women and lead, cadmium, and arsenic blood levels: a cross-sectional study from Taiwan

Background

The World Health Organization reported that more than 10 % of women are severely affected by infertility, making the condition a major worldwide public health problem. Lead (Pb), cadmium (Cd), and arsenic (As) are environmental pollutants that may contribute to reproductive disorders. This cross-sectional study investigated the association between blood concentrations of Pb, Cd, and As and risk factors for infertility in women.

Methods

Women who were infertile (N = 310) or pregnant (N = 57) were recruited from the gynecology and obstetrics department of a hospital. The participants were interviewed to obtain their sociodemographic, reproductive, and lifestyle information. The concentrations of Pb, Cd, and As in their blood samples were measured using inductively coupled plasma mass spectrometry.

Results

Our findings suggested that the concentrations of Pb and As, but not Cd, were significantly higher in the blood of infertile women than in that of pregnant women. A higher percentage of the infertile women consumed more alcohol, used Chinese herbal medicine more frequently, and lacked physical activity compared with the pregnant women. After accounting for potentially relevant predictors, we observed that blood Pb levels might be elevated by using Chinese herbal medicine 1–6 times per week (aOR = 2.82, p = 0.05). In addition, engaging in physical activity 1–2 times per week (aOR = 0.37, p = 0.05) might assist in reducing Pb accumulation in infertile women, though the p value was borderline.

Conclusions

Lack of physical activity and frequent use of Chinese herbal medicine may be associated with elevated blood Pb levels in infertile women. Chinese herbal medicine use was observed to increase the Pb body burden of both infertile and pregnant women in this study. The risk–benefit for Chinese herbal medicine intake should be evaluated by women of childbearing age.

Do the Levels of Maternal Plasma Trace Elements Affect Fetal Nuchal Translucency Thickness?

OBJECTIVE

Fetal nuchal translucency (NT) thickness is an important marker for prenatal screening; however, studies focusing on the correlation between maternal trace element levels and NT thickness are limited. The aim of this study was to evaluate maternal trace element levels during the first trimester and to investigate the association between maternal trace element levels and fetal NT thickness.

METHODS

In total, 113 samples were obtained from singleton pregnant women. Maternal plasma samples were collected in the first trimester of gestation. Plasma trace element levels were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Nuchal translucency thickness was measured using ultrasonography at 10-14 weeks of gestation.

RESULTS

We found that maternal plasma potassium (K) levels had a significant negative correlation with both NT (r = -0.230, p < 0.05) and NT Multiples of the Median (NT MoM) (r = -0.206, p < 0.05). After adjustment for potential confounders, log-transformed maternal plasma potassium levels in the first trimester were significantly associated with fetal NT (NT MoM: β = -0.68, p < 0.05; NT: β = -1.20, p < 0.01). Although not statistically significant, the As, Hg and Pb levels in maternal plasma were positively correlated with NT, and the Mg, Cu, Zn, Na and Ca levels were negatively correlated with NT.

CONCLUSION

Maternal plasma K levels during the first trimester appeared to be associated with NT thickness. The essential elements tended to decrease NT thickness, and non-essential elements tended to increase it.

Fetal exposure to environmental neurotoxins in Taiwan

Mercury (Hg), lead (Pb), cadmium (Cd), and arsenic (As) are recognized neurotoxins in children that particularly affect neurodevelopment and intellectual performance. Based on the hypothesis that the fetal basis of adult disease is fetal toxic exposure that results in adverse outcomes in adulthood, we explored the concentrations of key neurotoxins (i.e., Hg, Pb, Cd, and As) in meconium to identify the risk factors associated with these concentrations. From January 2007 to December 2009, 545 mother-infant pairs were recruited. The geometric mean concentrations of Pb and As in the meconium of babies of foreign-born mothers (22.9 and 38.1 µg/kg dry weight, respectively) were significantly greater than those of babies of Taiwan-born mothers (17.5 and 33.0 µg/kg dry weight, respectively). Maternal age (≥30 y), maternal education, use of traditional Chinese herbs during pregnancy, and fish cutlet consumption (≥3 meals/wk) were risk factors associated with concentrations of key prenatal neurotoxins. The Taiwan government should focus more attention on providing intervention programs for immigrant mothers to help protect the health of unborn babies. Further investigation on how multiple neurotoxins influence prenatal neurodevelopment is warranted.

Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Gestational lead exposure induces developmental abnormalities and up-regulates apoptosis of fetal cerebellar cells in rats

Lead (Pb), a known environmental toxicant, adversely affects almost all organ systems. In this study, we investigated the effects of maternal lead exposure on fetal rat cerebellum. Female Sprague-Dawley rats were given lead nitrate in drinking water (0, 0.5, and 1%) for two weeks before conception, and during pregnancy. Fetuses were collected by caesarian section on gestational day 21 and observed for developmental abnormalities. The fetal cerebellar sections from control and 1% lead group were stained with cresyl violet. Immunohistochemical expressions of p53, Bax, Bcl-2, and caspase 3 were quantified by AnalySIS image analyzer (Life Science, Germany). Lead exposure induced developmental abnormalities of eyes, ear, limbs, neck and ventral abdominal wall; however, these abnormalities were commonly seen in the 1% lead-treated group. In addition, lead also caused fetal mortality and reduced body growth in both dose groups and reduced brain weight in the 1% lead-treated group. The fetal cerebella from the 1% lead-treated group showed unorganized cerebellar cortical layers, and degenerative changes in granule and Purkinje cells such as the formation of clumps of Nissl granules. An increase in Bax and caspase 3, and a decrease in Bcl-2 (p < 0.05), but not in p53, showed apoptosis of the neurons. In conclusion, gestational lead exposure in rats induces fetal toxicity and developmental abnormalities. The lead exposure also impairs development of cerebellar layers, induces structural changes, and apoptosis in the fetal cerebellar cortex. These results suggest that lead exposure during gestation is extremely toxic to developing cerebellum in rats.

Prenatal lead exposure and relationship with maternal exposure determinants in a public maternity hospital of La Plata, Argentina

Prenatal lead exposure is a health hazard that may cause cognitive development impairments and other adverse effects in children. We conducted a cross sectional study analyzing cord blood lead levels (CBLL) of newborns and their relationship with maternal determinants of lead exposure. Mothers answered a questionnaire about socio-demographic, lifestyle habits and environmental characteristics. We used Mann-Whitney's test to compare CBLL geometrical means (GM) corresponding to the presence or absence of each lead exposure determinant, and Chi square test to study the relationship between CBLL and maternal lead exposure determinants. A total of 159 newborns participated in the study. CBLL GM was 2.1 μg/dL; and 25% of the participants had a measurable CBLL (LOQ=3.3 μg/dl). Although the participants had several determinants of lead exposure, we only found a significant relationship with inside household determinants, such as presence of lead piping (p=0.026), unplastered walls (p=0.046) and peeling paint (p=0.048). Our results show that CBLL GM was similar to that reported in several studies conducted around the world. However, 25% of the participants might have some degree of risk for lead poisoning.

Exposure of lead to mothers and their new born infants, residents of industrial and domestic areas of Pakistan

Prenatal and early-life exposure to lead (Pb) is hypothesized to have adverse effects on childhood health. The aim of this study was to evaluate the prenatal exposure to Pb and its adverse effects on mothers and their infants who are residents of industrial (exposed) and domestic areas (referents) in Karachi, Pakistan. The biological samples (scalp hair and blood) of mother-infants pairs were analyzed for Pb levels by atomic absorption spectrometry after microwave-assisted acid digestion method. The Pb levels in scalp hair and blood samples of exposed mothers were found in the range of 7.52-8.70 μg/g and 115-270 μg/L, respectively, which were significantly higher than those values obtained for referent mothers (p < 0.001). The Pb levels in the blood (umbilical cord) and hair of neonates of exposed mother that were found in the range of 83-178 μg/L and 4.95-7.23 μg/g, respectively, were significantly higher than the obtained values of referent neonates (p > 0.001). The correlation between maternal and cord blood of both groups was found in the range of 0.708-0.724 (p < 0.01). It was observed that there were higher Pb burdens in exposed mothers and their infants as compared to referent mothers-neonates.

Environmental induction of the fetal epigenome

The healthy adult is the result of successful interaction between the maternal environment and the developing fetal epigenome. The Barker hypothesis first suggested that in utero exposure to the maternal environment impacts adult health and disease. Since the origin of this theory, numerous studies have lent further support. Epigenomic alteration involves DNA methylation and histone modifications. Pregnancy, when the epigenome is typically actively programmed, is a vulnerable time, when exposures may have the most profound epigenetic effect. Recent advances have allowed an understanding of the extent and mechanism by which environmental exposures alter the epigenome of the fetus. Healthcare providers who treat and counsel reproductive-age women are in a unique position to protect against these epigenetic alterations and therefore prevent adverse impact on the developing fetus that may manifest throughout life.

Low-level prenatal lead exposure alters auditory recognition memory in 2-month-old infants: an event-related potentials (ERPs) study

This study used event-related potentials (ERPs) to assess effects of low-level prenatal lead exposure on auditory recognition memory in 2-month-old infants. Infants were divided into four groups according to cord-blood lead concentration: (1) <2.00 μ g/dL, (2) 2.00-2.99 μ g/dL, (3) 3.0-3.7 μ g/dL, and (4) ≥3.7 μ g/dL. The first group showed the normally expected differences in P2, P750, and late slow wave (LSW) amplitudes elicited by mothers' and strangers' voices. These differences were not observed for one or more ERP components in the other groups. Thus, there was electrophysiological evidence of poorer auditory recognition memory at 2 months with cord-blood lead ≥2.00 μ g/dL.

Tobacco smoke exposure during pregnancy increases maternal blood lead levels affecting neonate birth weight

To assess the effect of lead exposure from cigarette smoke on fetal growth, blood lead concentrations were measured using inductively coupled plasma mass spectrometry in 150 healthy pregnant women. Mean lead concentrations in plasma and whole blood were significantly higher in the smoking group compared with the nonsmoking group in each trimester of pregnancy (p < 0.001). Logistic regression analysis showed the highest impact of the number of cigarettes smoked per day for serum lead concentration (β = 0.238; p < 0.05), while in whole blood, it was duration of smoking before conception (β = 0.297; p < 0.001). Birth weight of the smoking mothers' infants was significantly lower (mean ± SEM, 3,192 ± 50.8 and 3,569 ± 49.6 g, respectively; p < 0.001) and negatively correlated with lead levels in plasma (r = -0.38; p < 0.001) and in whole blood (r = -0.27; p < 0.001). Therefore, it is suggested that smoking during pregnancy increases lead concentrations in maternal blood. Fetal exposure to low doses of lead in utero may be a serious risk factor causing lower birth weight.

Sources of potential lead exposure among pregnant women in New Mexico

The objectives of this study were to ascertain the prevalence and potential sources of lead exposure among pregnant women residing in a socially-disadvantaged immigrant community in Albuquerque, New Mexico. Pregnant women (n = 140) receiving prenatal care through a community clinic participated in a structured interview and screening to measure their blood lead levels (BLLs). Potential sources of lead exposure were ascertained by the CDC and New Mexico Department of Health questionnaires. Self-reported risk factors were examined as predictors of BLLs using multiple linear regression and partial least squares discriminant analysis. Most patients were Spanish-speaking (88.6%), Latina (95%), foreign-born (87.1%), lacked health insurance (86.4%), and had a high school education or lower (84.3%). While risk factors were prevalent in this population, only three women (2.1%) had BLLs ≥3 μg/dL. Results of multivariate analyses demonstrated that pica symptoms in pregnancy, history of elevated BLLs before pregnancy, use of non-commercial pottery, and living in older houses were important predictors of elevated BLLs. Although the prevalence of other risk factors relevant to immigrant communities (i.e., use of traditional/folk remedies and cosmetics, seasonings and food products from Mexico) was high, they were not predictive of elevated BLLs. Clinics providing prenatal care to immigrant Hispanic communities should carefully assess patients' pica symptoms, use of non-commercial pottery, and a history of elevated BLLs. Moreover, additional efforts need to focus on the development of screening questionnaires which better reflect exposures of concern in this population.

Lead in liver and kidney of exposed rats: aging accumulation study

The concentration of lead in liver and kidneys of Wistar rats, fed with lead since fetal period in relation to their age and to a control group, was determined. A group of rats was exposed to lead acetate (n=30) in drinking water and the other group was exposed to normal water (n=20). Samples were collected from rats aging between 1 and 11 months and were analyzed by Energy Dispersive X-ray Fluorescence (EDXRF) without any chemical preparation. The EDXRF results were assessed by the PIXE (Proton Induced X-ray Emission) technique. The formaldehyde used to preserve the samples was also analyzed by ETAAS (Electro-Thermal Atomic Absorption Spectrometry) in order to verify if there was any loss of lead from the samples to the formaldehyde. We found that the loss was not significant (<2%). Concerning the mean values of the lead concentration measured in the contaminated soft tissues, in liver they range from 6 to 22μgg(-1), and in kidneys from 44 to 79μgg(-1). The control rats show, in general, values below the EDXRF detection limit (2μgg(-1)). The ratio kidney/liver ranges from 2 to 10 and is strongly positively correlated with the age of the animals. A Spearman correlation matrix to investigate the correlation between elemental concentrations and the dependence of these concentrations with age showed that there is a strong positive correlation with age for lead in the liver but not in the kidney. The correlation matrix showed also that the concentration of lead in these two soft tissues is not correlated. The lead accumulation in liver is made by different plateaus that strongly decrease with age. It was verified the existence of two levels of accumulation in kidney, not very highlighted, which might be indicative of a maximum accumulation level for lead in kidney.

Metal exposure and reproductive disorders in indigenous communities living along the Pilcomayo River, Bolivia

BACKGROUND

The Pilcomayo River is polluted by tailings and effluents from upstream mining activities, which contain high levels of metals. The Weenhayek live along this river and are likely to have elevated exposure.

OBJECTIVES

To assess whether the Weenhayek have increased risk of reproductive and developmental disorders related to elevated metal exposure in comparison with a reference population.

METHODS

We assessed reproductive and developmental outcomes, i.e. fertility, fetal loss, congenital anomalies, and walking onset by means of structured interviews. We sampled hair, water and fish to assess the relative exposure of the Weenhayek. Samples were analyzed for Pb and Cd with ICP-MS techniques.

RESULTS

The Weenhayek communities studied had a higher prevalence of small families (OR 2.7, 95% CI 1.3-6.0) and delayed walking onset (OR 2.7, 95% CI 1.4-5.1) than the reference population. Median Pb levels in Weenhayek hair were 2-5 times higher than in the reference population, while Cd levels were not elevated. In water and fish, both Pb and Cd levels were increased in the Weenhayek area.

CONCLUSIONS

We found indications for increased risks of small families and delayed walking onset among the Weenhayek living along the Pilcomayo River. Lactants form a high risk group for lead exposure.

Assessment of essential and nonessential metals and different metal exposure biomarkers in the human placenta in a population from the south of Portugal

The general population is exposed to metals as trace amounts of metallic compounds are present in air, water, and food. Information on background exposures and biomarker concentrations of environmental chemicals in the general Portuguese population is limited. Therefore, the purpose of this study was to determine the levels of important nonessential metals with recognized toxicity cadmium (Cd) and lead (Pb) and essential metals copper (Cu), nickel (Ni), chromium (Cr), and zinc (Zn) in placentas of mothers living in south Portugal (Algarve). Due to the difficulty in establishing the effects of chemicals in a complex and variable environment, this study also aimed to examine the response of biomarkers, such as biochemical changes that occurs at subcellular levels in the presence of contaminants. The investigated biomarkers in placentas indicative of metal exposure or damage included the metallothioneins (MT), delta-aminolevulinic acid dehydratase (ALAD) (specific for Pb), and lipid peroxidation (LPO) as an index of oxidative stress damage. Moreover, HJ-BIPLOT was applied in order to identify and categorize mothers vulnerable to environmental contamination in this region. Metal concentrations in the placenta were not excessive but within the range found in most European studies. In general, the biomarkers MT and LPO were positively correlated with metal levels, while with ALAD the opposite occurred, indicating the selected battery of biomarkers were suitable to study the effects of metals on human placenta. Further, the application of multivariate analysis with HJ-BIPLOT showed that most significant factors contributing to maternal and fetal exposures via placenta were dietary and smoking habits.