Maternal blood lead level during pregnancy in South Central Los Angeles.

Twenty-five years of public health efforts produced a striking reduction in lead exposure; the blood lead average in the United States has decreased to less than 20% of levels measured in the 1970s. However, poor minority groups that live in large urban centers are still at high risk for elevated lead levels. In this study, our data showed that pregnant immigrants (n = 1,428) who live in South Central Los Angeles--one of the most economically depressed regions of California--have significantly higher (p < .0001) blood lead levels (geometric mean = 2.3 microg/dl [0.11 micromol/l]) than 504 pregnant nonimmigrants (geometric mean = 1.9 microg/dl [0.09 micromol/l]). The most important factors associated with lower blood lead levels in both groups were younger age; more-recent date of blood sampling (i.e., decreasing secular trend); and blood sampling in mid-autumn, instead of mid-spring (i.e., seasonal trend). Blood lead levels of immigrants were strongly dependent on time elapsed since immigration to the United States; each natural log increase in years of residence was associated with an approximately 19% decrease in blood lead levels. Although blood lead means for both groups were almost the same as the estimated national average, 25 of the 30 cases of elevated blood lead (i.e., > or = 10 microg/dl [0.48 micromol/l) occurred in the immigrant group. The odds ratio (95% confidence intervals within parentheses) for having elevated blood lead levels (a) was 9.3 (1.9, 45.8) if the immigrant engaged in pica; (b) was 3.8 (1.4, 10.5) if the immigrant had low dietary calcium intake during pregnancy; and (c) was .65 (.43, .98) for every natural log unit increase of years of residence in the United States. The control of pica and dietary calcium intake may offer a means of reducing lead exposure in immigrants.     

Blood Lead Levels in Children in South Central Los Angeles

We retrospectively reviewed 3 679 pediatric records from King/Drew Medical Center, south central Los Angeles, between 1991 and 1994. Blood lead levels of children were followed to age 18 y. Patients were not referred specifically for lead poisoning. The sample was primarily Latino. Geometric mean blood lead peaked at 6.7 μg/dl (0.32 μmol/l) between 2 and 3 y of age. There was a downward secular trend and a seasonal trend. Males had higher lead levels than females. Children who lived in several zipcode areas, in which the lowest family incomes were reported, had higher lead levels. More Latino children had higher lead levels than African American children. Latino children (i.e., 20.2%) who were 1–5 y of age had blood lead levels that were ≤ 10 μg/dl. Young Latino children in this zone of Los Angeles may be at increased risk for lead exposure.     

Association of maternal blood lead level during pregnancy with child blood lead level and pregnancy outcome in Kuwait

High blood lead levels (BLL) in pregnancy are associated with poor pregnancy outcome and neuro-behavioral deficits in infants. We investigated the prevalence of high BLL in pregnant women and its impact on pregnancy outcome in Kuwait. Blood from 194 mother-infant pairs were analyzed for lead by Atomic Absorption Spectrophotometry. Data were collected on birth weight, crown-heel length, head circumference, APGAR score, gestational age, and placental weight. Results revealed that 28% of pregnant women and 58% of infants had BLL >10 g/dL. Cord BLL was significantly higher than maternal BLL (10.92 vs. 5.77 g/dL, p < .001). Maternal BLL was not significantly associated with any of the outcome variables tested, whereas, cord BLL was a significant negative predictor of APGAR score only in boys. A significant proportion of pregnant women and their children in Kuwait have lead levels well above the safety limit, which is a matter of public health concern.     

Low-level lead exposure and elevations in blood pressure during pregnancy

Background

Lead exposure is associated with elevated blood pressure during pregnancy; however, the magnitude of this relationship at low exposure levels is unclear.

Objectives

Our goal was to determine the association between low-level lead exposure and blood pressure during late pregnancy.

Methods

We collected admission and maximum (based on systolic) blood pressures during labor and delivery among 285 women in Baltimore, Maryland. We measured umbilical cord blood lead using inductively coupled plasma mass spectrometry. Multivariable models were adjusted for age, race, median household income, parity, smoking during pregnancy, prepregnancy body mass index, and anemia. These models were used to calculate benchmark dose values.

Results

Geometric mean cord blood lead was 0.66 μg/dL (95% confidence interval, 0.61–0.70). Comparing blood pressure measurements between those in the highest and those in the lowest quartile of lead exposure, we observed a 6.87-mmHg (1.51–12.21 mmHg) increase in admission systolic blood pressure and a 4.40-mmHg (0.21–8.59 mmHg) increase in admission diastolic blood pressure after adjustment for confounders. Corresponding values for maximum blood pressure increase were 7.72 (1.83–13.60) and 8.33 (1.14–15.53) mmHg. Benchmark dose lower limit values for a 1-SD increase in blood pressure were < 2 μg/dL blood lead for all blood pressure end points.

Conclusions

A significant association between low-level lead exposures and elevations in maternal blood pressure during labor and delivery can be observed at umbilical blood lead levels < 2 μg/dL.     

Blood lead level and blood pressure of bus drivers in Bangkok, Thailand

This study aims to evaluate blood lead level (PbB) and blood pressure of bus drivers in Bangkok, Thailand, after the phasing out of lead in gasoline. The subjects comprised of 439 male bus drivers whose age ranged between 23 and 59 yr with the mean age of 42 +/- 8 yr. Average working experience was 10 +/- 7 yr. The mean of the systolic and diastolic blood pressure were 131 +/- 17 and 81 +/- 11 mmHg, respectively. PbB ranged from 2.5 to 16.2 microg/dl with the mean PbB of 6.3 microg/dl. Prevalence rate of systolic and diastolic hypertension among bus drivers were 23.0% and 18.2%, respectively. There were significant correlations between PbB and blood pressure both in systolic and diastolic blood pressure after controlling for age, BMI, alcohol consumption, smoking and physical exercise. However, the data on psycho-social factors which may affect on blood pressure of bus drivers were not available. Therefore, further study is needed to clarify the relationship between blood pressure and psycho-social stress among bus drivers in Bangkok. These findings suggested lead exposure at low PbB is related to increases in blood pressure.     

Blood lead levels during pregnancy

Summary A cross-sectional study of the variation in blood-lead levels throughout pregnancy was carried out on 165 women living in a rural area and 19 women living in an urban area. The mean blood-lead levels of both groups did not differ significantly from those of non-pregnant controls (27 rural and 19 urban). There was, however, a significant decrease in blood-lead levels throughout pregnancy, the magnitude of which was greater than the dilution effect of the concurrent increase in plasma volume. Women living in the urban area, whether pregnant or not, had significantly higher blood-lead levels than did those in the rural area. The mean blood-lead levels of 23 neonates was significantly lower at 6 days than their mothers' at term.These observations suggest that throughout pregnancy there is either an increasing placental deposition of lead or an increasing rate of transfer of lead to foetal tissues or a possible increased loss of body lead via other routes, e.g., urine.The higher blood-lead levels observed for the urban populations reflect increased environmental contamination with lead.     

Increases in hypertension and blood pressure during pregnancy with increased bone lead levels

Prior studies have revealed associations of current lead exposure (blood lead) and past lead exposure (bone lead) with risks of hypertension and elevated blood pressure. The authors examined the effects of blood and bone lead on hypertension and elevated blood pressure in the third trimester and postpartum among 1,006 women enrolled in Los Angeles prenatal care clinics between 1995 and 2001. The authors measured bone lead concentration by K-shell x-ray fluorescence in the tibia (mean = 8.0 micro g/g (standard deviation (SD) 11.4)) and calcaneus (heel) (mean = 10.7 micro g/g (SD 11.9)). Geometric mean prenatal and postnatal blood lead levels were 1.9 micro g/dl (geometric SD +3.6/-1.0) and 2.3 micro g/dl (geometric SD +4.3/-1.2), respectively. For each 10- micro g/g increase in calcaneus bone lead level, the odds ratio for third-trimester hypertension (systolic blood pressure > or =140 mmHg or diastolic blood pressure > or =90 mmHg) was 1.86 (95% confidence interval (CI): 1.04, 3.32). In normotensive subjects, each 10- micro g/g increase in calcaneus bone lead level was associated with a 0.70-mmHg (95% CI: 0.04, 1.36) increase in third-trimester systolic blood pressure and a 0.54-mmHg (95% CI: 0.01, 1.08) increase in diastolic blood pressure. Tibia bone lead concentration was not related to hypertension or elevated blood pressure either in the third trimester or postpartum, nor was calcaneus bone lead related to postpartum hypertension or elevated blood pressure. Past lead exposure influences hypertension and elevated blood pressure during pregnancy. Controlling blood pressure may require reduction of lead exposure long before pregnancy.     

Blood pressure and blood lead in surveys in Wales

The association between blood pressure and blood lead level was examined in two population surveys in Wales. In a survey of 1,721 male and female subjects throughout the principality, there was evidence of a marked relation of blood pressure with age, but when this was removed no residual association with blood lead remained. In a survey of 1,164 older men in Caerphilly, there was no evidence of an association between blood lead and either resting blood pressure or the rise in blood pressure during a cold pressor test.     

血铅浓度对血压、心电图的影响

以某企业铅作业工人血铅偏高者作为观察组,与同企业铅作业工人血铅正常组、非铅作业对照组进行比较,发现观察组血压升高及心电图异常的比例均高于正常组和对照组,正常组与对照组比较差异无统计学意义。建议采取有效措施控制职业性铅危害,降低职业性铅接触人群心血管疾病发病率。     

Patterns and determinants of blood lead during pregnancy

The pattern of blood lead during pregnancy was investigated in a cohort of 195 women who, between October 1992 and February 1995, entered prenatal care at Magee-Womens Hospital in Pittsburgh, Pennsylvania, by week 13 of pregnancy. Blood was drawn as many as five times, once in each of the first two trimesters and a maximum of three times in the third trimester. Blood lead determinations were made by atomic absorption spectrophotometry. Potential sources or modifiers of lead exposure were collected by interviews, including sociodemographic, pregnancy history, occupational, and lifestyle data. Results confirmed a previously reported U-shaped curve in blood lead concentration during pregnancy as well as findings that blood lead levels increase with age, smoking, lower educational level, and African-American race and decrease with history of breastfeeding and higher intake of calcium. Additionally, interactions were found between time since last menstrual period and both maternal age and calcium. Specifically, older mothers showed steeper increases in blood lead concentrations during the latter half of pregnancy than did younger mothers, and intake of calcium had a protective effect only in the latter half of pregnancy, an effect that became stronger as pregnancy progressed. These findings provide further evidence that lead is mobilized from bone during the latter half of pregnancy and that calcium intake may prevent bone demineralization.     

营养教育与妊娠后期孕妇血压及白蛋白的关系

目的 探讨妊娠期营养指导对改善孕妇营养、减少妊娠期高血压疾病的效果.方法 选择山西医科大学第二医院产科门诊进行产前检查的孕妇共426名,按照是否愿意接受定期营养指导分为观察组和对照组,在其孕期监测体重、宫高、腹围、收缩压、舒张压及水肿情况,对部分孕妇检测血清蛋白水平.结果 ①观察组孕妇妊娠晚期舒张压均值低于对照组(t=2.37,P<0.05),观察组孕妇妊娠晚期妊娠高血压疾病发生率低于对照组(χ2=4.56,P<0.05);②两组妊娠中期孕妇体重与收缩压和舒张压之间呈正相关(均P=0.001);两组妊娠晚期孕妇体重与舒张压之间呈正相关(均P=0.001);③在妊娠期进行营养宣教后,观察组妊娠晚期孕妇水肿发生数减少(χ2=7.92,P<0.01),血清蛋白水平明显升高(t=2.96,P<0.01).结论 在妊娠期进行营养宣教可减少妊娠晚期的妊娠期高血压疾病的发生,可提高孕妇血清蛋白水平,减少孕妇水肿的发生.     

Seasonal variation in bone lead contribution to blood lead during pregnancy

Population blood lead level (PbB) often shows seasonal variation, frequently being higher in summer and lower in winter. As vitamin D metabolites also show seasonal variability, and the metabolites are associated with bone metabolism, some authors have posited a role for bone lead release in seasonal PbB changes. We made third trimester and postdelivery PbB measurements on 414 immigrant women (98% Latina) in Los Angeles. We measured in vivo tibia and calcaneus (heel) lead concentration postdelivery via K-shell X-ray fluorescence. We saw evidence of seasonal variation in prenatal PbB, but not postnatal PbB. PbB was highest in spring and lowest in autumn. Tibia lead concentration was associated with prenatal PbB, as reported before. The contribution of tibia lead to prenatal PbB varied seasonally, with the greatest contribution occurring in the winter quarter and the least in the summer quarter. The temporal pattern of bone lead contribution to PbB follows the seasonal alteration of insolation. There was no seasonal component in prenatal PbB associated with calcaneus lead, nor were there seasonal variations in either calcaneus or tibia lead contributions to postnatal PbB. Bone turnover in the third trimester of pregnancy may be higher in winter months than in summer months, resulting in greater fetal lead exposure in spring than at other times of the year.     

Maternal bone lead contribution to blood lead during and after pregnancy

We examined bone lead contribution to blood lead in a group of 311 immigrant women, 99% from Latin America, during the third trimester of pregnancy and 1 to 2 months after delivery. We measured in vivo tibia and calcaneus (heel) bone lead concentration in the postdelivery period with K shell X-ray fluorescence. Prenatal and postnatal geometric mean (range) blood lead level was 2.2 microg/dL (0.4 to 38.7) and 2.8 microg/dL (0.4 to 25.4), reflecting low current exposure. Postnatal blood lead level was significantly higher than prenatal (P<0.0001). Mean (range) tibia and calcaneus lead concentration was 6.7 microg/g (-33.7 to 62.2) and 8.4 microg/g (- 30.1 to 66.4), reflecting varying but elevated past lead exposure. Mean calcaneus lead concentration was significantly higher than mean tibia lead concentration (P = 0.055). Variance-weighted multiple regression and structural equation models showed that both calcaneus and tibia lead were directly associated with prenatal blood lead but only calcaneus lead was associated with postnatal blood lead. Increasing natural log years in the United States independently predicted decreasing calcaneus and third-trimester blood lead. The data suggest that while some exogenous lead sources and modulators of blood lead level, such as use of lead-glazed pottery and calcium in the diet, control lead exposure during and after pregnancy, endogenous lead sources from past exposure before immigration continue to influence blood lead levels in this sample.     

Spatial analysis of bioavailable soil lead concentrations in Los Angeles, California

Lead (Pb) poisoning causes permanent neurologic and developmental disorders and remains an important environmental health problem for US children, despite removal of Pb from gasoline and household paints. To better understand the contribution of Pb from historical traffic and residential Pb based paint to soil Pb concentrations in Los Angeles, we analyzed 550 soil Pb samples from south central Los Angeles County, CA, in relation to land-use patterns (commercial, industrial, residential, and parks and open areas) and proximity to freeways, highways, and major arterials. House age variables (surrogates of historical Pb-based paint) and traffic index variables (surrogates of historical traffic) were created at different buffer distances (10-5000 m).Total and bioavailable Pb concentrations near freeways and major arterials were significantly higher than those collected elsewhere. Total and bioavailable Pb concentrations were highly correlated (r=0.96) after the removal of one outlier. Both parcel-age related variables and traffic variables were important predictors of current soil bioavailable Pb concentrations. Average age of parcels within 30 m and length of small streets within 3000 m explained 57% and 38% of the variance, respectively, in soil bioavailable Pb concentrations in residential areas away from freeways and major arterials (N=44). Road length of freeways within 750 m explained 28% of bioavailable Pb concentrations in parks and open areas (N=26). Multi-variable regression models predicted 16-61% of the variances in bioavailable Pb concentrations, depending on land-use type and spatial relationship to roadways. Based on these models a map of spatial distributions of soil Pb concentrations was created for the Los Angeles area that shows promise as a screening tool to evaluate continued Pb poisoning in children.     

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.     

Association between blood lead level and blood pressure in aborigines and others in central Taiwan

To investigate the relationship between the blood lead level (BLL) and blood pressure among aborigines and non-aborigines in central Taiwan, a community-based survey that included demographic data, medical history, and blood chemistry analyses was conducted among 2,565 adults during an annual health examination. BLLs were analyzed using a graphite furnace atomic absorption spectrometer (AAS). There was a dose response among the non-aborigines (high BLL odds ratio = 2.97, compared with low BLL) but not among aborigines. Based on multiple linear regression models, BLLs were positively correlated with both systolic (an increase of 0.85 mm Hg/microg/dL) and diastolic (an increase of 0.48 mm Hg/microg/dL) blood pressures after adjusting for age, gender, ethnic group, alcohol consumption, and body mass index. BLLs were higher among aborigines than non-aborigines and were significantly correlated with blood pressure, particularly systolic pressure. The association should be considered causal.