Variation in blood lead and hematocrit levels during pregnancy in a socioeconomically disadvantaged population

Association of maternal lead exposure with the risk of preterm: a meta-analysis

BACKGROUND

The relationship between maternal lead level and risk of preterm birth (PTB) remained controversial. Therefore, herein we performed this meta-analysis to investigate the association of maternal blood, urine and cord blood lead level with the risk of PTB using observational studies.

METHODS

A systematic search was conducted in PubMed, EMBASE and Ovid Medline databases from inception to August 2019, and sixteen studies with 65600 participants investigating the association between maternal lead level and PTB were included in our meta-analysis. Odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated for the highest versus lowest lead level by random-effects model.

RESULTS

Overall, the pooled OR of all included articles for the highest versus lowest PTB score was 1.29 (95% CI = 1.14-1.46; I2 = 80.4%, p < .001), and the results revealed a direct and significant relationship between second and third trimester blood lead level (BLL) and PTB (OR 2nd trimester= 1.61, 95% CI = 1.08-2.40, OR 3rd trimester= 1.57, 95% CI = 1.11-2.23).

CONCLUSION

Results of this meta-analysis showed that maternal BLL is directly associated with the risk of PTB.

Vitamin D Treatment during Pregnancy and Maternal and Neonatal Cord Blood Metal Concentrations at Delivery: Results of a Randomized Controlled Trial in Bangladesh

BACKGROUND

Vitamin D improves absorption of calcium; however, in animal studies vitamin D also increases the absorption of toxic metals, such as lead and cadmium.

OBJECTIVES

We examined maternal and neonatal cord blood levels of lead, cadmium, manganese, and mercury after supplementation with vitamin D during pregnancy.

METHODS

The Maternal Vitamin D for Infant Growth trial was a randomized, placebo-controlled, multi-arm study of maternal vitamin D supplementation during pregnancy in Dhaka, Bangladesh (NCT01924013). Women were randomized during their second trimester to blinded weekly doses of placebo or 4,200, 16,800, or 28,000 IU of vitamin D3 throughout pregnancy. Each group had 118-239 maternal blood specimens and 100-201 cord blood samples analyzed. Metals were measured using inductively coupled plasma mass spectrometry. Unadjusted estimates from linear regression models were expressed as percentage differences. Cord blood cadmium was analyzed as detectable or undetectable with log-binomial regression.

RESULTS

Maternal cadmium, mercury, and manganese levels were nearly identical across groups. Maternal lead levels were 6.3%, 7.4%, and 6.0% higher in the treatment groups (4,200, 16,800, and 28,000 IU, respectively) vs. placebo; however, 95% confidence intervals (CIs) showed that differences from 4.1% lower to 20% higher were compatible with the data. In treatment groups (4,200, 16,800, 28,000 IU) vs. placebo, neonatal cord blood lead levels were 8.5% (95% CI: - 3.5 , 22), 16% (95% CI: 3.3, 30), and 11% (95% CI: 0.4, 23) higher and had higher risk of detectable cadmium, relative risk ( RR ) = 2.2 (95% CI: 1.3, 3.7), RR = 1.4 (95% CI: 0.8, 2.5), RR = 1.7 (95% CI: 1.0, 2.9).

DISCUSSION

Vitamin D supplementation from the second trimester of pregnancy did not influence maternal cadmium, mercury, or manganese levels at delivery. Vitamin D was associated with nonsignificant increases in maternal lead and with significant increases in cord blood lead and cadmium. These associations were not dose dependent. Given that there are no safe levels of metals in infants, the observed increases in cord blood lead and cadmium require further exploration. https://doi.org/10.1289/EHP7265.

Patterns and dietary determinants of essential and toxic elements in blood measured in mid-pregnancy: The Norwegian Environmental Biobank

BACKGROUND

Inadequate stores or intakes of essential minerals in pregnancy, or too high exposure to both toxic and essential elements, can have adverse effects on mother and child. The main aims of this study were to 1) describe the concentrations and patterns of essential and toxic elements measured in maternal whole blood during pregnancy; 2) identify dietary, lifestyle and sociodemographic determinants of element status; and 3) explore the impact of iron deficiency on blood element concentrations.

METHODS

This study is based on blood samples collected from 2982 women in gestational week 18 in The Norwegian Mother and Child Cohort study (MoBa) which were analyzed as part of the Norwegian Environmental Biobank. We derived blood element patterns by exploratory factor analysis, and associations between blood element patterns and diet were explored using sparse partial least squares (sPLS) regression.

RESULTS

Blood concentrations were determined for the essential elements (in the order of most abundant) Zn > Cu > Se > Mn > Mo > Co, and the toxic metals Pb > As > Hg > Cd > Tl. The concentrations were in ranges that were similar to or sometimes more favorable than in other pregnant and non-pregnant European women. We identified two blood element patterns; one including Zn, Se and Mn and another including Hg and As. For the Zn-Se-Mn pattern, use of multimineral supplements was the most important dietary determinant, while a high score in the Hg-As pattern was mainly determined by seafood consumption. Concentrations of Mn, Cd and Co were significantly higher in women with iron deficiency (plasma ferritin < 12 μg/L) than in women with plasma ferritin ≥ 12 μg/L.

CONCLUSION

Our study illustrates complex relationships and coexistence of essential and toxic elements. Their potential interplay adds to the challenges of studies investigating health effects related to either diet or toxicants.

Blood total mercury and methylmercury among pregnant mothers in Charleston, South Carolina, USA

BACKGROUND

Maternal blood total mercury (THg) is a biomarker for prenatal methylmercury (MeHg) exposure. Few studies have quantified both blood THg and MeHg during pregnancy, and few studies have reported longitudinal trends.

OBJECTIVES

We analyzed blood THg and MeHg in a cohort of pregnant mothers in Charleston, South Carolina (n = 83), and investigated whether blood THg or MeHg changed between early and late gestation.

METHODS

THg and MeHg were analyzed in blood samples from early (12 ± 1.7 weeks) and late (35 ± 2.2 weeks) gestation.

RESULTS

Blood %MeHg (of THg) averaged 63% (range: 10-114%) and 61% (range: 12-117%) during early and late gestation, respectively. In unadjusted analyses, blood MeHg decreased from early to late pregnancy (paired t-test, p = 0.04), while THg did not change (paired t-test, p = 0.34). When blood MeHg was normalized by the hematocrit, this decrease was no longer statistically significant (paired t-test, p = 0.09).

CONCLUSIONS

In unadjusted analyses, blood MeHg, but not THg, decreased significantly between early and late gestation; this decrease was due in part to hemodilution. Percent MeHg (of THg) varied by up to one order of magnitude. Results highlight the importance of Hg speciation in maternal blood samples to assess prenatal MeHg exposure.

Maternal-infant interaction as an influence on infant adiposity

OBJECTIVES

The aim of this research is to identify whether specific aspects of the early life psychosocial environment such as quality of home and maternal-infant interaction are associated with increased infant adiposity, in a disadvantaged population in the United States.

METHODS

Data on 121 mother-infant pairs from the Albany Pregnancy and Infancy Lead Study were analyzed using three multiple linear regression models with subscapular skinfold thickness (SST), triceps skinfold thickness (TST), and weight z-scores at 12 months of age as outcome variables. Maternal-infant interaction was indexed by the Nursing Child Assessment Teaching Scales (NCATS) and home environment quality was indexed by the Home Observation for Measurement of the Environment (HOME).

RESULTS

In models including infant birth weight, cigarette use in second trimester, infant caloric intake at 9-12 months, size at birth for gestational age, infant sex, and mother's prepregnancy BMI, specific subscales of NCATs predicted infant adiposity z-scores. Poorer mother's response to infant distress was associated with greater SST ( β = -0.20, P = .02), TST ( β = -0.19, P = .04), and weight ( β = -0.14, P = .05). Better maternal sensitivity to infant cues was associated with larger SST ( β = 0.25, P < .01), while mother's poorer social-emotional growth fostering predicted greater SST ( β = -0.23, P < .01) and weight ( β = -0.16, P = .03). Better scores on HOME Organization of the Environment were associated with greater SST ( β = 0.34, P = .02) and TST ( β = 0.33, P = .04).

CONCLUSIONS

Emotionally relevant aspects of the maternal-infant interaction predicted infant adiposity, though in different directions. This indicates that the psychosocial environment, through maternal behavior, may influence infant adiposity. However, the general home environment was not consistently related to infant adiposity.

Maternal and fetal exposure to cadmium, lead, manganese and mercury: The MIREC study

Given the susceptibility of the fetus to toxicants, it is important to estimate their exposure. Approximately 2000 pregnant women were recruited in 2008-2011 from 10 cities across Canada. Cd, Pb, Mn and total Hg were measured in maternal blood from the 1st and 3rd trimesters, umbilical cord blood, and infant meconium. Nutrient intakes of vitamin D, iron, and calcium (Ca) were assessed using a food frequency questionnaire and a dietary supplement questionnaire. Median concentrations in 1st trimester maternal blood (n = 1938) were 0.20, 8.79 and 0.70 μg/L for Cd, Mn and Hg, respectively, and 0.60 μg/dL for Pb. While the median difference between the paired 1st and 3rd trimester concentrations of Cd was 0, there was a significant decrease in Pb (0.04 μg/dL) and Hg (0.12 μg/L) and an increase in Mn (3.30 μg/L) concentrations over the course of the pregnancy. While Cd was rarely detected in cord blood (19%) or meconium (3%), median Pb (0.77 μg/dL), Mn (31.87 μg/L) and Hg (0.80 μg/L) concentrations in cord blood were significantly higher than in maternal blood. Significant negative associations were observed between estimated Ca intake and maternal Cd, Pb, Mn and Hg, as well as cord blood Pb. Vitamin D intake was associated with lower maternal Cd, Pb, and Mn as well as Pb in cord blood. Even at current metal exposure levels, increasing dietary Ca and vitamin D intake during pregnancy may be associated with lower maternal blood Pb and Cd concentrations and lower Pb in cord blood.

Bone remodeling during pregnancy and post-partum assessed by metal lead levels and isotopic concentrations

Bone remodeling is normally evaluated using bone turnover markers/indices as indicators of bone resorption and formation. However, during pregnancy and post-partum, there have been inconsistent results between and within biomarkers for bone formation and resorption. These differences may relate to pregnancy-related changes in metabolism and/or hemodilution altering measured marker levels. An alternative approach to evaluating bone remodeling is to use the metal lead (Pb) concentrations and Pb isotopic compositions in blood. These measurements can also provide information on the amount of Pb that is mobilized from the maternal skeleton. Despite some similarities with accepted bone turnover markers, the Pb data demonstrate increased bone resorption throughout pregnancy that further continues post-partum independent of length of breast-feeding, dietary intake and resumption of menses. Furthermore the isotopic measurements are not affected by hemodilution. These data confirm calcium balance studies that indicate increased bone resorption throughout pregnancy and lactation. They also indicate potentially major public health implications of the transfer of maternal Pb burden to the fetus and new born.

Association of blood lead levels with methylenetetrahydrofolate reductase polymorphisms among Chinese pregnant women in Wuhan city

BACKGROUND

Pregnancy is an important stimulus of bone lead release. Elevated blood lead levels (BLLs) may cause adverse pregnancy outcomes for mothers and harmful lead effects on fetuses. However, the reports about maternal BLL changes during pregnancy are conflicting to some extent. This article is to explore the variations in BLLs among pregnant women. The relationships of BLLs with methylenetetrahydrofolate reductase (MTHFR) gene C677T, A1298C, and G1793A polymorphisms, which are associated with bone resorption, were also studied. A total of 973 women, including 234, 249, and 248 women in their first, second, and third trimesters, respectively, and 242 non-pregnant women, were recruited at the Wuhan Women and Children Medical Health Center.

METHODS

BLLs were determined using a graphite furnace atomic absorption spectrometer. Single-nucleotide polymorphisms of MTHFR were identified with the TaqMan probe method.

RESULTS

The geometric mean (geometric standard deviation) of BLLs was 16.2 (1.78) μg/L for all participants. All the studied MTHFR alleles were in Hardy-Weinberg equilibrium. Multiple-linear regression analysis revealed the following results. Among the pregnant women, those that carried MTHFR 677CC (i.e. wild-genotype homozygote) and 1298CC (i.e. mutant-genotype homozygote) exhibited higher BLLs than those that carried 677CT/TT (standardized β = 0.074, P = 0.042) and 1298AC/AA (standardized β = 0.077, P = 0.035) when other covariates (e.g., age, no. of children, education and income, etc.) were adjusted. The BLLs of pregnant women consistently decreased during the pregnancy and these levels positively correlated with BMI (standard β = 0.086-0.096, P<0.05).

CONCLUSIONS

The 1298CC mutant-type homozygote in the MTHFR gene is a risk factor for high BLLs among low-level environmental lead-exposed Chinese pregnant women, whose BLLs consistently decreased during gestation.

Applying the community partnership approach to human biology research

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

Changes in low levels of lead over the course of pregnancy and the association with birth outcomes

Data are lacking on the effect of low level prenatal lead exposure. We examined the change in blood lead from the second trimester until delivery and the association between maternal and cord blood lead and birth outcomes in 98 participants of the CANDLE birth cohort study. Mixed effects models were constructed to assess blood lead change over pregnancy and regression models were used to explore the relationship with cord blood lead, characteristics effecting maternal lead, birth weight and gestational age. Overall, the geometric mean maternal blood level was 0.43 μg/dL. Maternal blood lead at each time point was predictive of cord blood lead level. A 0.1 μg/dL increase in second trimester lead was associated with lower birth weight and pre-term birth. Maternal blood lead below 1 μg/dL behaves in a manner similar to lead at higher levels and is associated with a small decrease in birth weight and gestational age.

Growth of infants' length, weight, head and arm circumferences in relation to low levels of blood lead measured serially

To determine whether levels of blood lead during gestation and infancy that are below the CDC action level of 10 microg/dl affect infant growth, we studied 211 disadvantaged mother-infant pairs from Albany, NY. Mothers' lead levels were low (second trimester chi = 2.8 microg/dl) as were infants' (chi = 3.3 microg/dl at 6 months; 6.4 microg/dl at 12 months). Multiple linear regression analyses showed that second trimester lead levels were related to reduced head circumference at 6 and 12 months. Infants of mothers with second trimester lead at or above the median (>or=3 microg/dl) exhibited negative associations between blood lead and head circumference at 6 and 12 months, and with weight-for-age, weight-for-length, and upper arm circumference at 6 months, but those below the median did not. Infants' 6-month lead level was related to head circumference at 12 months in the total sample, and in the subsample of infants whose blood lead was above the infants' 6-month blood lead median. Infants were also grouped by changes in their relative blood lead status, that is, above vs. below the median, from second trimester to 12 months of age. Infants whose lead levels changed from above to below the median were larger than infants whose lead levels went from below to above the median. The results suggest that lead may affect some dimensions of infant growth at levels below 10 microg/dl, but effects of lead levels less than 3 microg/dl are not evident in this sample.

Relationships of blood lead to calcium, iron, and vitamin C intakes in Brazilian pregnant women

BACKGROUND & AIMS

This study aimed to determine the relationship between blood lead concentrations and calcium, iron and vitamin C dietary intakes of pregnant women.

METHODS

Included in the study were 55 women admitted to a hospital, for delivery, from June to August 2002. A food frequency questionnaire was applied to determine calcium, iron and vitamin C intakes, and a general questionnaire to obtain data on demographic-socioeconomic condition, obstetric history, smoking habit, and alcohol intake. Blood lead and haemoglobin were determined, respectively, by atomic absorption spectrometry and by the haemoglobinometer HemoCue. Multiple linear regression models were used to determine the relationship between blood lead and calcium, iron and vitamin C intakes, and haemoglobin levels, controlling for confounders.

RESULTS

The final model of the regression analysis detected an inverse relationship between blood lead and age of the women (p=0.011), haemoglobin (p=0.001), vitamin C (p=0.012), and calcium intake (p<0.001) (R(2)=0.952). One hundred percent, 98.2% and 43.6% of the women were below the adequate intake (AI) for calcium, and below the recommended dietary allowances (RDA) for iron, and vitamin C, respectively.

CONCLUSION

Despite the small sample size, the results of this study suggest that maternal age, haemoglobin, vitamin C intake, and calcium intake may interfere with blood concentrations of lead.

Advancing biocultural models by working with communities: a partnership approach

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

Reduced intellectual development in children with prenatal lead exposure

OBJECTIVE

Low-level postnatal lead exposure is associated with poor intellectual development in children, although effects of prenatal exposure are less well studied. We hypothesized that prenatal lead exposure would have a more powerful and lasting impact on child development than postnatal exposure.

DESIGN

We used generalized linear mixed models with random intercept and slope to analyze the pattern of lead effect of the cohort from pregnancy through 10 years of age on child IQ from 6 to 10 years. We statistically evaluated dose-response nonlinearity.

PARTICIPANTS

A cohort of 175 children, 150 of whom had complete data for all included covariates, attended the National Institute of Perinatology in Mexico City from 1987 through 2002.

EVALUATIONS/MEASUREMENTS

We used the Wechsler Intelligence Scale for Children-Revised, Spanish version, to measure IQ. Blood lead (BPb) was measured by a reference laboratory of the Centers for Disease Control and Prevention (CDC) quality assurance program for BPb.

RESULTS

Geometric mean BPb during pregnancy was 8.0 microg/dL (range, 1-33 microg/dL), from 1 through 5 years was 9.8 microg/dL (2.8-36.4 microg/dL), and from 6 through 10 years was 6.2 microg/dL (2.2-18.6 microg/dL). IQ at 6-10 years decreased significantly only with increasing natural-log third-trimester BPb (beta=-3.90; 95% confidence interval, -6.45 to -1.36), controlling for other BPb and covariates. The dose-response BPb-IQ function was log-linear, not linear-linear.

CONCLUSIONS

Lead exposure around 28 weeks gestation is a critical period for later child intellectual development, with lasting and possibly permanent effects. There was no evidence of a threshold; the strongest lead effects on IQ occurred within the first few micrograms of BPb.

RELEVANCE TO CLINICAL PRACTICE

Current CDC action limits for children applied to pregnant women permit most lead-associated child IQ decreases measured over the studied BPb range.

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.

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

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

Blood lead changes during pregnancy and postpartum with calcium supplementation

Pregnancy and lactation are times of physiologic stress during which bone turnover is accelerated. Previous studies have demonstrated that there is increased mobilization of lead from the maternal skeleton at this time and that calcium supplementation may have a protective effect. Ten immigrants to Australia were provided with either calcium carbonate or a complex calcium supplement (approximately 1 g/day) during pregnancy and for 6 months postpartum. Two immigrant subjects who did not conceive acted as controls. Sampling involved monthly venous blood samples throughout pregnancy and every 2 months postpartum, and quarterly environmental samples and 6-day duplicate diets. The geometric mean blood lead at the time of first sampling was 2.4 microg/dL (range, 1.4-6.5). Increases in blood lead during the third trimester, corrected for hematocrit, compared with the minimum value observed, varied from 10 to 50%, with a geometric mean of 25%. The increases generally occurred at 6-8 months gestation, in contrast with that found for a previous cohort, characterized by very low calcium intakes, where the increases occurred at 3-6 months. Large increases in blood lead concentration were found during the postpartum period compared with those during pregnancy; blood lead concentrations increased by between 30 and 95% (geometric mean 65%; n = 8) from the minimum value observed during late pregnancy. From late pregnancy through postpartum, there were significant increases in the lead isotopic ratios from the minimum value observed during late pregnancy for 3 of 8 subjects (p < 0.01). The observed changes are considered to reflect increases in mobilization of lead from the skeleton despite calcium supplementation. The identical isotopic ratios in maternal and cord blood provide further confirmation of placental transfer of lead. The extra flux released from bone during late pregnancy and postpartum varies from 50 to 380 microg lead (geometric mean, 145 microg lead) compared with 330 microg lead in the previous cohort. For subjects replete in calcium, the delay in increase in blood lead and halving of the extra flux released from bone during late pregnancy and postpartum may provide less lead exposure to the developing fetus and newly born infant. Nevertheless, as shown in several other studies on calcium relationships with bone turnover, calcium supplementation appears to provide limited benefit for lead toxicity during lactation.

Environmental Pollution in Urban Environments and Human Biology

▪ Abstract  The biocultural approach of anthropologists is well suited to understand the interrelationship of urbanism and human biology. Urbanism is a social construction that has continuously changed and presented novel adaptive challenges to its residents. Urban living today involves several biological challenges, of which one is pollution. Using three different types of pollutants as examples, air pollution, lead, and noise, the impact of pollution on human biology (mortality, morbidity, reproduction, and development) can be seen. Chronic exposure to low levels of these pollutants has a small impact on the individual, but so many people are exposed to pollution that the effect species-wide is substantial. Also, disproportionate pollutant exposure by socioeconomically disadvantaged groups exacerbates risk of poor health and well being.

Blood lead levels during pregnancy in women living in Rio de Janeiro, Brazil

The present study was designed to determine variations in blood lead levels during pregnancy and the influence of physiological anemia during this period on these findings. An exploratory study was made of a cohort of 38 pregnant women whose blood was tested for lead level and erythrocyte counts at different stages of pregnancy. The values obtained for lead were adjusted to take account of the erythrocyte count values, in order to control the influence of pregnancy-related physiological anemia on blood lead levels. A statistically significant increase in blood lead levels at a 5% level was observed between the first and third trimester. The median blood lead levels for the first, second and third trimester were 5.1 microg/dl, 5.9 microg/dl, and 8.25 microg/dl, respectively (Kruskal-Wallis=11.9, P<0.002). Statistical significance was also shown for raw data, when blood lead levels were not adjusted to erythrocyte count values. The median blood lead levels observed in this latter situation were 5.55 microg/dl, 5.65 microg/dl and 7.3 microg/dl, respectively (Kruskal-Wallis=8.3, P<0.02). It is concluded that there was a significant increase in blood lead concentration during pregnancy in this group of women.