Lead poisoning among pregnant women in New York City: risk factors and screening practices

The Intersection of Immigrant and Environmental Health: A Scoping Review of Observational Population Exposure and Epidemiologic Studies

BACKGROUND

Transnational immigration has increased since the 1950s. In countries such as the United States, immigrants now account for > 15 % of the population. Although differences in health between immigrants and nonimmigrants are well documented, it is unclear how environmental exposures contribute to these disparities.

OBJECTIVES

We summarized current knowledge comparing immigrants' and nonimmigrants' exposure to and health effects of environmental exposures.

METHODS

We conducted a title and abstract review on articles identified through PubMed and selected those that assessed environmental exposures or health effects separately for immigrants and nonimmigrants. After a full text review, we extracted the main findings from eligible studies and categorized each article as exposure-focused, health-focused, or both. We also noted each study's exposure of interest, study location, exposure and statistical methods, immigrant and comparison groups, and the intersecting socioeconomic characteristics controlled for.

RESULTS

We conducted a title and abstract review on 3,705 articles, a full text review on 84, and extracted findings from 50 studies. There were 43 studies that investigated exposure (e.g., metals, organic compounds, fine particulate matter, hazardous air pollutants) disparities, but only 12 studies that assessed health disparities (e.g., mortality, select morbidities). Multiple studies reported higher exposures in immigrants compared with nonimmigrants. Among immigrants, studies sometimes observed exposure disparities by country of origin and time since immigration. Of the 50 studies, 43 were conducted in North America.

DISCUSSION

The environmental health of immigrants remains an understudied area, especially outside of North America. Although most identified studies explored potential exposure disparities, few investigated subsequent differences in health effects. Future research should investigate environmental health disparities of immigrants, especially outside North America. Additional research gaps include the role of immigrants' country of origin and time since immigration, as well as the combined effects of immigrant status with intersecting socioeconomic characteristics, such as race/ethnicity, income, and education attainment. https://doi.org/10.1289/EHP9855.

Risk-Factor Based Lead Screening and Correlation with Blood Lead Levels in Pregnancy

OBJECTIVES

Lead exposure has devastating neurologic consequences for children and may begin in utero. The American College of Obstetricians and Gynecologists recommends prenatal lead screening using a risk factor-based approach rather than universal blood testing. The clinical utility of this approach has not been studied. We evaluated a risk-factor based questionnaire to detect elevated blood lead levels in pregnancy.

METHODS

We performed a secondary analysis of a cohort of parturients enrolled to evaluate the association of lead with hypertensive disorders of pregnancy. We included participants in this analysis if they had a singleton pregnancy ≥ 34 weeks' gestation with blood lead levels recorded. Participants completed a lead risk factor survey modified for pregnancy. We defined elevated blood lead as ≥ 2 μg/dL, as this was the clinically reportable level.

RESULTS

Of 102 participants enrolled in the cohort, 92 had blood lead measured as part of the study. The vast majority (78%) had 1 or more risk factor for elevated lead using the questionnaire yet none had clinical blood lead testing during routine visits. Only two participants (2.2%) had elevated blood lead levels. The questionnaire had high sensitivity but poor specificity for predicting detectable lead levels (sensitivity 100%, specificity 22%).

CONCLUSIONS FOR PRACTICE

Prenatal risk-factor based lead screening appears underutilized in practice and does not adequately discriminate between those with and without elevated blood levels. Given the complexity of the risk factor-based approach and underutilization, the benefit and cost-effectiveness of universal lead testing should be further explored.

Blood Lead Levels in U.S. Women of Childbearing Age, 1976-2016

BACKGROUND

Lead can adversely affect maternal and child health across a wide range of exposures; developing fetuses and breastfeeding infants may be particularly vulnerable. We describe the distribution of blood lead levels (BLLs) in U.S. women of childbearing age and associations with sociodemographic, reproductive, smoking, and housing characteristics over a 40-y period.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) II, NHANES III Phase I and Phase II, and 1999-2016 continuous NHANES were used to describe the distribution of BLLs (given in micrograms per deciliter; 1μg/dL=0.0483μmol/L) in U.S. women 15-49 years of age between 1976 and 2016. For all women with valid BLLs (n=22,408), geometric mean (GM) BLLs and estimated prevalence of BLLs ≥5μg/dL were calculated overall and by selected demographic characteristics. For NHANES II, estimated prevalence of BLLs ≥10 and ≥20μg/dL were also calculated.

RESULTS

The most recent GM BLLs (2007-2010 and 2011-2016, respectively) were 0.81μg/dL [95% confidence interval (CI): 0.79, 0.84] and 0.61μg/dL (95% CI: 0.59, 0.64). In comparison, GM BLLs in earlier periods (1976-1980, 1988-1991, and 1991-1994) were 10.37μg/dL (95% CI: 9.95, 10.79), 1.85μg/dL (95% CI: 1.75, 1.94), and 1.53μg/dL (95% CI: 1.45, 1.60), respectively. In 2011-2016, 0.7% of women of childbearing age had BLLs ≥5μg/dL, and higher BLLs were associated with older age, other race/ethnicity, birthplace outside the United States, four or more live births, exposure to secondhand tobacco smoke, and ever pregnant or not currently pregnant.

DISCUSSION

Lead exposure in U.S. women of childbearing age is generally low and has substantially decreased over this 40-y period. However, based on these estimates, there are still at least 500,000 U.S. women being exposed to lead at levels that may harm developing fetuses or breastfeeding infants. Identifying high-risk women who are or intend to become pregnant remains an important public health issue. https://doi.org/10.1289/EHP5925.

Blood Lead Levels in U.S. Women of Childbearing Age, 1976-2016

BACKGROUND

Lead can adversely affect maternal and child health across a wide range of exposures; developing fetuses and breastfeeding infants may be particularly vulnerable. We describe the distribution of blood lead levels (BLLs) in U.S. women of childbearing age and associations with sociodemographic, reproductive, smoking, and housing characteristics over a 40-y period.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) II, NHANES III Phase I and Phase II, and 1999-2016 continuous NHANES were used to describe the distribution of BLLs (given in micrograms per deciliter; 1μg/dL=0.0483μmol/L) in U.S. women 15-49 years of age between 1976 and 2016. For all women with valid BLLs (n=22,408), geometric mean (GM) BLLs and estimated prevalence of BLLs ≥5μg/dL were calculated overall and by selected demographic characteristics. For NHANES II, estimated prevalence of BLLs ≥10 and ≥20μg/dL were also calculated.

RESULTS

The most recent GM BLLs (2007-2010 and 2011-2016, respectively) were 0.81μg/dL [95% confidence interval (CI): 0.79, 0.84] and 0.61μg/dL (95% CI: 0.59, 0.64). In comparison, GM BLLs in earlier periods (1976-1980, 1988-1991, and 1991-1994) were 10.37μg/dL (95% CI: 9.95, 10.79), 1.85μg/dL (95% CI: 1.75, 1.94), and 1.53μg/dL (95% CI: 1.45, 1.60), respectively. In 2011-2016, 0.7% of women of childbearing age had BLLs ≥5μg/dL, and higher BLLs were associated with older age, other race/ethnicity, birthplace outside the United States, four or more live births, exposure to secondhand tobacco smoke, and ever pregnant or not currently pregnant.

DISCUSSION

Lead exposure in U.S. women of childbearing age is generally low and has substantially decreased over this 40-y period. However, based on these estimates, there are still at least 500,000 U.S. women being exposed to lead at levels that may harm developing fetuses or breastfeeding infants. Identifying high-risk women who are or intend to become pregnant remains an important public health issue. https://doi.org/10.1289/EHP5925.

Blood lead levels in pregnant women referring to midwifery clinic in a referral center in Tehran

Background:

Lead effects on children and pregnant women are grave, and screening tests would be logical to detect high blood lead levels (BLLs) in early stages.

Materials and Methods:

Blood samples were taken from the pregnant mothers who referred to midwifery clinic with further phone interview postdelivery.

Results:

In 100 patients evaluated, the mean age was 29 ± 5 years (median interquartile range gestational age of 33 [24, 37] weeks). There was a significant correlation between polluted residential area and median BLL (P = 0.044) and substance exposure (P = 0.02). The median BLL was significantly lower in those without a history of lead toxicity in the family (P = 0.003). The only factor that could predict the BLL levels lower than 3.2 and 5 μg/dL was living in the nonindustrial area. All pregnant women delivered full-term live babies.

Conclusion:

Positive history of lead toxicity in the family and living in polluted areas may pose a higher BLL in pregnant women.

Metal Concentrations in Newcomer Women and Environmental Exposures: A Scoping Review

Newcomer women from developing countries are recognized to be at risk for elevated exposures to environmental contaminants and associated negative health effects. As such, data on exposure sources and contaminant body burden concentrations is critical in the development of effective public health policies and interventions in support of newcomer health. We conducted a scoping review to gather evidence on important toxic metals of health concern, lead (Pb), mercury (Hg) and cadmium (Cd), and their concentrations and potential exposure sources among newcomer women. An initial 420 articles were identified through the databases MEDLINE, EMBASE and Scopus, many reporting by ethnicity rather than newcomer/immigrant status. Several articles reported metal concentrations for other biomarkers but did not include blood, nor stratify results. From the remainder, we selected a total of 10 articles for full textual review, which reported blood Pb, Hg or Cd levels for newcomer women and/or stratified blood metal results according to foreign birth or country of origin. Three of the articles reported higher Pb, Hg and Cd concentrations in newcomer women compared to their native-borne counterparts. Exposures identified as contributing to elevated Pb, Hg and Cd blood concentrations included: pica behaviour, the use of lead-glazed cookware or eye cosmetics, and fish/shellfish consumption. The review revealed a limited availability of data on metal body burden concentrations, exposure sources and routes among newcomer women specifically. More research is needed to better understand the extent to which newcomer women are disproportionately at risk of elevated metal exposures due to either country of origin or current exposures and to inform relevant, multi-national risk management strategies.

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.

Pica during pregnancy among Mexican-born women: a formative study

Although pica, the craving and purposive consumption of non-food substances, is common among many populations, especially during pregnancy, the health consequences are not well understood. Further, very little is known about pica among Mexican populations in the United States and Mexico. Therefore, we conducted formative research to understand pica in this understudied population. Our objectives were to identify the frequency and types of pica behaviours, to understand perceived aetiologies and consequences of pica and to ascertain if the behaviour was common enough to warrant a larger study. We held nine focus group discussions (three in the Salinas Valley, California; six in Xoxocotla, Morelos, Mexico) with 76 Mexican-born women who were currently pregnant or had delivered within the past 2 years. Earth, adobe, bean stones and ice were the most commonly reported pica substances. Twenty-eight of the 76 participants (37%) reported ever engaging in pica; 22 participants (29%) reported doing so during pregnancy. The proportion of women reporting pica in the United States and Mexico was 43% and 34%, respectively. Women attributed pica to the overwhelming organoleptic appeal of pica substances (especially smell and texture) and to micronutrient deficiencies. Perceived consequences of unfulfilled pica cravings were birthmarks or fetal loss; fulfilled pica cravings were also thought to be generally harmful to the mother or child, with several women specifying toxic lead, pesticides or 'worms'. In sum, pica among Mexican women is common enough to warrant a larger epidemiologic study of its sociodemographic correlates and physiological consequences.

A review of physiological and behavioral changes during pregnancy and lactation: potential exposure factors and data gaps

Exposures to environmental contaminants can pose risks to pregnant women's health, their developing fetuses, children, and adults later in their lives. Assessing risks to this potentially susceptible population requires a sound understanding of the physiological and behavioral changes that occur during pregnancy and lactation. Many physiological and anatomical changes occur in a woman's organ systems during the course of pregnancy and lactation. For example, blood volume and cardiac output increase during pregnancy, and other metabolic functions are altered to provide for the demands of the fetus. During lactation, nutritional demands are greater than during pregnancy. There are also changes in behavior during both pregnancy and lactation. For example, water consumption during pregnancy and lactation increases. These behavioral and physiological changes can lead to different environmental exposures than these women might otherwise experience in the absence of pregnancy or lactation. This paper provides a summary of information from the published literature related to behavioral and physiological changes in pregnant and lactating women that may affect their exposure or susceptibility to environmental contaminants, provides potentially useful exposure factor data for this population of women, and highlights data gaps.

Trace element content in tea brewed in traditional metallic and stainless steel teapots

The migration of metals in tea brewed in metallic teapots was investigated. The teapots were obtained from North Africa stores in Brussels in 2005-2006 and in 2011. Chinese gunpowder green tea, the most commonly used tea in the Moroccan community, was used to prepare the tea. Tea brewed in metallic teapots was compared to tea brewed in a glass vessel in order to evaluate the contribution of the tea and the teapots to the metal concentrations in the brewed tea. Tea samples were also collected in Moroccan households and in tearooms in Brussels. The elements As, Cd, Pb, Sn, Mn, Fe, Cr, Co, Ni, Cr, Cu, Zn, and Al were analyzed by high-resolution sector field inductively coupled mass spectrometry. The relationship between the metal composition of the alloy of the teapot and the metal concentration in tea was also investigated. Migration of Pb and to a lesser amount Ni, Cu, and Zn was observed in brass teapots and migration of Cd from a number of stainless steel teapots was observed. The soldering connecting the sprout to the teapot was shown to be an important source of Pb to the tea. High levels of Mn and Al were also observed in the brewed tea and these elements where shown to originate from the tea itself. Metal exposure from tea drinking was calculated for different tea consumption levels and different metal concentration levels and compared to toxicological reference values.

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.

Blood Pb Levels in pregnant Nigerian women in Abakaliki, South-Eastern Nigeria

Environmental lead (Pb) exposure and toxicity have been recognised as public health problems of global importance, affecting both the developed and developing nations. In this work, blood Pb of pregnant women that were not exposed to lead by their occupation (n = 349), with mean ± SD age of 27.0 ± 4.8 years and gestational age of 21.8 ± 3.1 weeks at recruitment were determined using atomic absorption spectrophotometer. The results showed that 309 (88.5 %) of the women had a mean ± SD blood Pb of 40.0 ± 16.5 μg/dl, which is higher than the current US Centre for Disease Prevention and Control action limit (>10 μg/dl). The observed high prevalence of elevated blood Pb levels may be related to maternal low socioeconomic status. Health education is, therefore, urgently needed to sensitise the general public and the policy makers of the level of Pb exposure in Abakaliki environment and the inherent health implications. In addition to mandatory environmental lead monitoring, blood Pb screening for would-be mother is recommended, and those whose blood Pb are found elevated should be appropriately treated.

Exposure sources and reasons for testing among women with low blood lead levels

Previous research has focused on highly elevated blood lead (PbB). This study examined reasons for testing and potential sources of exposure among women with PbBs less than 0.72 μmol/l (15 μg/dl). A questionnaire was mailed to 18- to 49-year-old women in upstate New York, USA, who were PbB tested in 2007. The most common testing reason was pregnancy among 125 women who returned the questionnaire. Among women tested for PbB during pregnancy, doctors ordered approximately 80% of tests regardless of lead level. Few women with PbBs less than 0.24 μmol/l (5 μg/dl) reported a potential source of lead exposure. However, among women with PbBs of 0.24-0.71 μmol/L (5-14.9 μg/dl), 29.2% had a job and 21.2% had a hobby with potential lead exposure. There are systematic differences in reasons for testing and exposure sources among women with PbBs less than 0.72 μmol/l and these differences have implications for screening.

Neurocysticercosis: risk and primary prevention strategies update

Neurocysticercosis results from the infestation of the central nervous system with invading tapeworm larvae. Though uncommon in the US prior to 1965, new cases are currently being diagnosed at an unprecedented rate. Drawing on environmental health, intervention and risk data retrieved from standard/alternative databases and in-country sources, we present an update and summary of modifiable risk factors and field-tested primary prevention measures. While points of intervention, subpopulations at risk and overall magnitude of the problem are addressed, particular attention is paid to defining risk reduction measures that can be adopted by individuals and high risk groups in the near-term to interrupt or eliminate pathways of exposure leading to disease transmission. Though global eradication is not attainable in the near future, effective preventative measures exist and should be taken now by international travellers and workers, US/foreign government agencies, and individuals living in endemic regions to reduce human suffering.

The clinical content of preconception care: environmental exposures

Environmental origins of disease risk and harm to health have been increasingly acknowledged for numerous outcomes, in both adult and pediatric populations. Adverse reproductive and developmental effects have also been linked to environmental exposures. In addition to the current queries about a patient's alcohol and smoking history, key determinants of a future pregnancy outcome should also be elicited during the preconception visit. These determinants include: (1) mercury intake via fish consumption; (2) nitrate exposure from well water sources; (3) exposure to chemical, physical, or biologic hazards on the job; and (4) lead and other toxic exposures--possibly from hobbies or the use of lead-glazed dinnerware in the home. Eliciting a detailed environmental history permits tailored recommendations to optimize the woman's health and that of her future pregnancy.

Elevated blood lead levels in pregnant women: identification of a high-risk population and interventions

There has been a significant decrease in the number of preschool children with elevated blood lead levels (BLL), from 88.2 to 4.4 per 10,000 children over the last three decades as shown by National Health and Nutritional Examination Survey (NHANES) data. However, there are still certain high-risk populations that have not been well studied. One such group is that of pregnant women. During pregnancy, BLL tends to increase due to greater bone turnover, which causes release of lead stored in bone. This increase may not affect the pregnant woman's health directly but could be extremely harmful to the rapidly developing central nervous system in the fetus as it crosses the placenta easily. This current study was undertaken to estimate the prevalence of elevated BLL in pregnant women in a community hospital, monitor the effect of routine preventive practices on maternal BLL, and to elucidate the relationship between maternal and neonatal BLL and their anthropometric indices. A retrospective chart review was conducted on all hospital deliveries occurring in the first six years after the initiation of universal blood lead screening of pregnant women (n=6880). The prevalence of elevated lead (> or =10 microg/dL) in our patient population was 1.7%. The factors associated with elevated lead levels were recent immigration to the US, poor socioeconomic status and low educational levels. Simple interventions such as hand washing as well as calcium and iron supplementation significantly reduced maternal BLL from 16.82+/-9.5 to 11.48+/-9.3 microg/dL (P<0.0001). A significant correlation (r=0.4, P<0.007) is present between the post-intervention but not the pre-intervention maternal BLL and the neonatal BLL. Given the vulnerability of the developing fetal brain and that CNS complications are associated with elevated lead levels, antenatal lead screening should be part of routine prenatal care. Simple preventive measures may play a role in decreasing maternal BLL and thereby decreasing transplacental transfer of lead to the fetus.

Globalization, binational communities, and imported food risks: results of an outbreak investigation of lead poisoning in Monterey County, California

OBJECTIVES

Although the burden of lead poisoning has decreased across developed countries, it remains the most prevalent environmental poison worldwide. Our objective was to investigate the sources of an outbreak of lead poisoning in Monterey County, California.

METHODS

An investigation in 3 county health department clinics in Monterey County, California, was conducted between 2001 and 2003 to identify risk factors for elevated blood lead levels (> or = 10 microg/dL) among children and pregnant women.

RESULTS

The prevalence of elevated blood lead levels was significantly higher in 1 of the 3 clinics (6% among screened children and 13% among prenatal patients). Risk factors included eating imported foods (relative risk [RR]=3.4; 95% confidence interval [CI]=1.2, 9.5) and having originated from the Zimatlan area of Oaxaca, Mexico, compared with other areas of Oaxaca (RR=4.0; 95% CI=1.7, 9.5). Home-prepared dried grasshoppers (chapulines) sent from Oaxaca were found to contain significant amounts of lead.

CONCLUSIONS

Consumption of foods imported from Oaxaca was identified as a risk factor for elevated blood lead levels in Monterey County, California. Lead-contaminated imported chapulines were identified as 1 source of lead poisoning, although other sources may also contribute to the observed findings. Food transport between binational communities presents a unique risk for the importation of environmental hazards [corrected]

Inadequate prenatal care and elevated blood lead levels among children born in Providence, Rhode Island: a population-based study

OBJECTIVE

This study was conducted to determine whether children born to mothers receiving inadequate prenatal care are at an increased risk for having an elevated blood lead level during early childhood.

METHODS

The authors conducted a population-based study of children born in Providence, Rhode Island, from 1997 to 2001 whose mothers had received adequate, intermediate, or inadequate prenatal care. The children's blood lead levels were compared between groups using bivariate and logistic regression. To understand the regulatory implications and public health impact of changing the definition of an elevated blood lead level, "elevated" was defined as 5 microg/dL, 10 microg/dL, and 15 microg/dL.

RESULTS

Children born to mothers who received inadequate prenatal care were at an elevated risk for having an elevated blood lead level later in life. This relationship remained statistically significant for each definition of elevated blood lead level and after controlling for other socio-economic status measures and birthweight (at 5 microg/dL, odds ratio [OR] = 1.36, 95% confidence interval [CI] 1.09, 1.68, p = 0.006; at 10 microg/dL, OR = 1.68, 95% CI 1.26, 2.24, p < 0.0004; at 15 microg/dL, OR = 1.83, 95% CI 1.10, 3.04, p = 0.019) represent an opportune moment to identify expectant mothers living in lead-contaminated environments.

CONCLUSIONS

Results suggest that conducting lead screening as a regular part of prenatal care provision could help identify women possibly experiencing ongoing lead exposure and help reduce or prevent exposures to their offspring.

Screening for elevated lead levels in childhood and pregnancy: an updated summary of evidence for the US Preventive Services Task Force

BACKGROUND

In 1996, the US Preventive Services Task Force provided recommendations for routine screening of asymptomatic children and pregnant women for elevated blood lead levels. This review updates the evidence for the benefits and harms of screening and intervention for elevated blood lead in asymptomatic children and pregnant women.

METHODS

We searched Medline, reference lists of review articles, and tables of contents of leading pediatric journals for studies published in 1995 or later that contained new information about the prevalence, diagnosis, natural course, or treatment of elevated lead levels in asymptomatic children aged 1 to 5 years and pregnant women.

RESULTS

The prevalence of elevated blood lead levels among children and women in the United States, like that in the general population, continues to decline sharply, primarily because of marked reductions in environmental exposure, but still varies substantially among different communities and populations. Similar to the findings in 1996, our searches did not identify direct evidence from controlled studies that screening children for elevated blood lead levels results in improved health outcomes, and there was no direct evidence identified from controlled studies that screening improves pregnancy or perinatal outcomes. No new relevant information regarding the accuracy of screening for lead toxicity was identified during the update, and we did not identify evidence that demonstrates that universal screening for blood lead results in better clinical outcomes than targeted screening. Substantial new relevant information regarding the adverse effects of screening and interventions was not identified.

CONCLUSIONS

There is no persuasive evidence that screening for elevated lead levels in asymptomatic children will improve clinical outcomes. For those children who are screened and found to have elevated levels, there is conflicting evidence demonstrating the clinical effectiveness of early detection and intervention.

Teratogen update: lead and pregnancy

This review focuses on the impacts of lead exposure on reproductive health and outcomes. High levels of paternal lead exposure (>40 microg/dl or >25 microg/dl for a period of years) appear to reduce fertility and to increase the risks of spontaneous abortion and reduced fetal growth (preterm delivery, low birth weight). Maternal blood lead levels of approximately 10 microg/dl have been linked to increased risks of pregnancy hypertension, spontaneous abortion, and reduced offspring neurobehavioral development. Somewhat higher maternal lead levels have been linked to reduced fetal growth. Some studies suggest a link between increased parental lead exposure and congenital malformations, although considerable uncertainty remains regarding the specific malformations and the dose-response relationships. Common methodological weaknesses of studies include potential exposure misclassifications due to the frequent unavailability of exposure biomarker measurements at biologically appropriate times and uncertainty regarding the best exposure biomarker(s) for the various outcomes. A special concern with regard to the pregnant woman is the possibility that a fetus might be exposed to lead mobilized from bone stores as a result of pregnancy-related metabolic changes, making fetal lead exposure the result of exposure to exogenous lead during pregnancy and exposure to endogenous lead accumulated by the woman prior to pregnancy. By reducing bone resorption, increased calcium intake during the second half of pregnancy might reduce the mobilization of lead from bone compartments, even at low blood lead levels. Subgroups of women who incurred substantial exposures to lead prior to pregnancy should be considered to be at increased risk.

Contents of chemical elements in stomach during prenatal development: different age-dependent dynamical changes and their significance

AIM: To observe dynamic of different chemical elements in stomach tissue during fetal development.

METHODS: To determine contents of the 21 chemical elements in each stomach samples from fetus aging four to ten months. The content values were compared to those from adult tissue samples, and the values for each month group were also analyzed for dynamic changes.

RESULTS: Three representations were found regarding the relationship between contents of the elements and ages of the fetus, including the positive correlative (K), reversely correlative (Na, Ca, P, Al, Cu, Zn, Fe, Mn, Cr, Sr, Li, Cd, Ba, Se) and irrelevant groups (Mg, Co, Ni, V, Pb, Ti).

CONCLUSION: The chemical elements’ contents in stomach tissues were found to change dynamically with the stomach weights. The age-dependent representations for different chemical elements during the prenatal development may be of some significance for assessing development of fetal stomach and some chemical elements. The data may be helpful for the nutritional balance of fetus and mothers during prenatal development and even the perinatal stages.