Re-Examination of Longitudinal Studies of Workers

This cross-sectional study examined the association between blood lead levels and neuropsychological and behavioral development of 139 children (7–9 y of age) who attended school in the southwestern part of Mexico City. A trained psychologist administered an IQ test to 84% of the children, and teachers graded them for agility, socialization, expression, and knowledge. Parents also answered a questionnaire on demographic and socioeconomic variables. Anodic stripping voltametry was used to determine blood lead levels. Regression models were used to determine the best predictors of IQ and teachers' rating scores. The mean blood lead level was 19.4 μg/dl (standard deviation [SD] = 7.6), with a geometric mean of 17.8 μg/dl (95% confidence interval [95% CI] = 16.5–19.1). Blood lead was the strongest predictor of full-scale IQ, and there was a significant negative trend between blood lead, full-scale IQ, and teachers' rating scores. In this study, children with higher levels of blood lead performed more poorly on psychometric tests and had poorrer educational attainment than their counterparts. These results suggest an association between neuropsychological and behavioral impairment and lead exposure.     

Blood Lead Levels in 2- to 3-Year-Old Children in the Greater Bilbao Area (Basque Country,Spain): Relation to Dust and Water Lead Levels

The objectives of this study were to determine blood lead levels in 2-y-old children in the Greater Bilbao Area (Basque Country, Spain) and to compare those levels with the lead content of different media (i.e., house dust, park dust and soil, and water) in the child's environment. Between May and September of 1992, 138 children, aged 2 to 3 y, were studied. All children were attended by pediatricians within the public health-care network, and their parents volunteered for the study. A venous blood sample was drawn from each child and was analyzed for lead level, and the parents answered a questionnaire that addressed the socioeconomic background and habits of the children. The environment was investigated in 42 cases. Blood lead levels exceeded 15 μg/dl in 2% of the children, and 14% of the children had levels that exceeded 10 μg/dl (geometric mean = 5.7 μg/dl [4.7–6.7 μg/dl]). Blood lead levels were higher among (a) children whose mothers worked outside the home, (b) children whose fathers had only a primary-level education, and (c) children who lived in houses constructed prior to 1950. The geometrical averages of lead in house dust, park soil, and park dust were 595, 299, and 136 μg/g, respectively. Statistically significant linear correlation was found between blood lead level and lead content in park dust, a finding that explained a 9% variation in blood lead level; a subgroup of these children was also found to have a strong linear association between blood lead and lead content in house dust.     

Stochastic Behavior of Trace Substances

An epidemiological survey was conducted in August 1991 to evaluate the impact of a public health program. The objective of the program was to decrease the level of exposure to lead of children who lived within 200 m of a lead-reclamation plant. In 1989, these children had a geometric mean blood lead level of 9.2 μg/dl (0.44 μmol/l). Children who were 6 mo to 10 y of age (N = 101) participated in the survey. Demographic and behavioral characteristics of the children and their parents were ascertained by interviewers. Blood samples were taken by venipuncture. Geometric mean blood lead levels were calculated by age in 1991 and by residence in 1989. In 1991, the geometric mean blood lead level had decreased to 5.0 μg/dl (0.24 μmol/l) in children. There was no difference in mean blood lead levels with respect to age or residence. From 1989 to 1991, a significant decrease in the proportion of children who engaged in hand-to-mouth activities was also observed. The lead-poisoning prevention program reached its main objective stated above. The success of this program was attributed to the coordinated actions of public agencies at both the provincial and local levels.     

Low-Level Lead Exposure and Blood Lead Levels in Children: A Cross-Sectional Survey

The authors studied 53 girls (44.5%) and 66 (55.5%) boys in Karachi, Pakistan, to determine their blood lead levels. The association between blood lead levels/water lead levels and the possible risk factors and symptoms associated with lead toxicity was explored. The mean lead level for the entire group was 7.9 μg/dl (standard deviation = 4.5 μg/dl). Thirty (25.2%) of the children had lead levels that exceeded 10 μg/dl; 12 (10.0%) of these had lead levels that exceeded 15 μg/dl. Thirteen (20.9%) of the children under the age of 6 yr (n = 62) had lead levels greater than 10 μg/dl, and 6 (9.6%) had levels in excess of 15 μg/dl. The authors found no association (p > .05) between high lead levels in water and blood lead levels in children. Mean blood lead levels were highest in the group of children exposed to various risk factors for lead absorption (e.g., exposure to paint, remodeling, and renovation; use of lead utensils; pica). There was a significant association between a history of exposure to paint/renovation activities and a history of pica. High blood lead levels in the children in Karachi stress the urgency for actions that control lead pollution. Screening programs should be instituted by the state. Individuals must become aware of lead's toxicity, and they must avoid substances that contain lead.     

Lead levels in Maryland construction workers

A cross-sectional study of unionized construction workers not currently known to be performing lead work was conducted. Participants completed an interviewer-administered questionnaire obtaining information about demographics, work history, other possible sources of lead exposure and health status (including hypertension, noise-induced hearing loss and renal disease). Blood was then obtained via venipuncture for whole blood lead level, hematocrit and free erythrocyte protoporphyrin determination. Two hundred and sixty-four Maryland construction workers had median whole blood lead determinations of 7 μg/dl and mean values of 8.0 μg/dl, with a skewed distribution ranging from 2 to 30 μg/dl. None were currently engaged in known lead work. Blood lead levels were significantly higher for the 124 who had ‘ever’ worked in demolition (8.8 μg/dl vs. 7.2 μg/dl, p = .004), and for the 79 who had ever burned paint and metal and welded on outdoor structures compared to the 48 who had done none of these activities (8.6 μg/dl vs. 6.8 μg/dl, p = .01). The 58 workers who had ever had workplace lead monitoring performed had higher lead levels (9.7 vs. 7.5 μg/dl, p = .003). Blood lead levels increased with age, and cigarette smoking. African Americans (N = 68) had higher lead levels (9.1 vs. 7.5 μg/dl, p = .01). There were only two women in the study, one with a lead level of 21 μg/dl and one, 7 μg/dl. Blood lead levels did not predict either systolic or diastolic blood pressure in this population. However, there was a significant interaction between race and lead as predictors of blood pressure, with blacks demonstrating a trend-significant correlation, and whites showing a nonsignificant but negative association. Demolition and hotwork on outdoor structures are known to cause acute episodes of lead poisoning. They also appear to cause slight but persistent increases in blood lead levels. Future workplace regulation should recognize and seek to maintain the low baseline now apparent even in urban, East Coast, construction workers. Am. J. Ind. Med. 31:188–194, 1997. © 1997 Wiley-Liss, Inc.     

Lead and Cadmium Exposure from Contaminated Soil among Residents of a Farm Area near an Industrial Site

In this study, the authors determined the degree of lead and cadmium exposure in a population that resided in an area with contaminated soil. The extent of exposure from soil pollution was also assessed. Lead and cadmium concentrations in blood of children and adults who resided in the contaminated area were measured, and cadmium concentration in urine of adults was also determined. An adult control group was recruited from a non-polluted area. The mean blood lead level in adults who resided in the polluted area was 9.8 μg/dl, compared with a mean level of 6.8 μg/dl in controls (p = .004). Urinary cadmium levels were well below the level associated with onset of symptoms, but the differences between levels in residents of the contaminated area (0.54 μg/gm creatinine) and levels in the controls (0.37 μg/gm creatinine) indicated that life-long cadmium exposure had been higher among the residents of the contaminated area (p = .086). The mean blood lead level and mean blood cadmium level in children were 5.2 μg/dl (maximum = 7.90 μg/dl) and 0.10 μg/l, respectively. Lead in soil accounted in large part for the differences in blood lead levels in children; however, blood cadmium levels were not associated with soil cadmium levels, but, rather, with consumption of home-grown vegetables.     

The Physiological Response of Animals to β-Nitronaphthalene

The effect of lead exposure on blood pressure in the modern industrial setting is controversial. In this study, we followed 67 workers in a lead-battery plant for 6–10 y, and blood pressure and blood lead levels were measured every 6 mo. Weight, height, alcohol intake, cigarette smoking, and age were recorded. Partial correlation coefficients showed that initial systolic blood pressure, age, and body mass index (i.e., weight/height squared) accounted for 25%, 30.9%, and 20.2%, respectively, of the variance in systolic blood pressure (p < .001 in all cases). Conversely, average blood lead levels (13 ± 3 tests/worker) accounted for only 0.4% of the variance (not significant). Repeated-measures analysis of variance showed a small—but significant—association between blood lead levels and systolic blood pressure. There was a negative correlation between blood lead levels and diastolic blood pressure. There were 18 men with average blood lead levels that were less than 30 μg/dl (average = 25 ± 3 μg/dl), and 32 men had levels of 40 μg/dl or more (average = 47 ± 6 μg/dl). The mean final systolic blood pressure, adjusted for age, and initial systolic blood pressure were 117 ± 13 mm Hg and 114 ± 11 mm Hg, respectively. We concluded that blood lead levels had no clinically significant effect on blood pressure in lead-battery workers. The main predictors of the follow-up systolic blood pressure were age, body mass index, and initial systolic blood-pressure measurements.     

Distribution of Blood Lead Levels in 1 047 Saudi Arabian Children with Respect to Province,Sex, and Age

Relationships between blood lead concentrations in 1 047 children aged 2 mo to 16 y and age, sex, and province (i.e., residence) were examined. The relationships were consistent with other studies, in which mean blood lead concentrations reportedly increased during the first 5 y of life, after which began to decrease, reaching a minimum at approximately 16 y of age. However, boys who were more than 6 y of age had higher blood lead concentrations than similarly aged girls. Blood lead levels of children living in the Eastern Province were higher than levels found in children from other provinces. Most of the children in this study who had elevated blood lead concentrations resided in small towns, e.g., Ehssa, Abqiq, Hofouf, rather than in cities such as Dammam and Dahran. Factors, such as socioeconomic status and cultural habits (e.g., diet, use of traditional remedies and cosmetics), may have contributed to this result.     

Change in blood lead concentration up to 1 year after a gunshot wound with a retained bullet

The authors studied the time course and prevalence of elevated blood lead concentrations and associated injury- and patient-specific factors during the first year following gunshot injury. They determined blood lead levels at mean time points of 0.3, 3.1, 18.7, 94.5, 188.3, and 349.4 days after injury in a volunteer sample of 451 subjects from a Los Angeles, California, trauma center who sustained a first-time gunshot injury with a retained projectile in 2000-2002. In mixed-model analyses, blood lead levels increased with time postinjury (p < 0.0005) up to 3 months, with number of retained fragments (p < 0.0005), and with increasing age (p < 0.0005). Increased blood lead concentration as a function of fragmentation was approximately 30% higher among subjects who had suffered bone fracture in the torso (p < 0.0005). Subjects with bullets or fragments lodged near bone (p < 0.0005) or near joints (p = 0.032) had higher blood lead levels. Logistic models correctly predicted a blood lead elevation of >/=20 micro g/dl in 81% and 85% of subjects at 3 and 6 months postinjury, respectively. The prevalence of elevated blood lead was 11.8% at 3 months and 2.6% at 12 months. The authors recommend continued surveillance of blood lead levels after gunshot injury for patients with key indicators.     

Blood lead levels in Japanese children: Effects of passive smoking

Blood lead levels (BLLs) of 188 pediatric patients were measured and their parents were queried as to the smoking style in their home. Their mean BLL was 3.16 μg/dl, which was among the lowest levels in the world, and none of them had levels of over 10 μ g/dl. Preschool children ( 1 to 6 years of age) with parents who smoked in the same room had a significantly higher BLL (mean; 4.15 μ g/dl) than those with parents who never smoked (mean; 3.06 μ g/dl) (P<0.01). However, the mean BLL of school children (6 to 15 years of age) with parents who smoked in the same room was not significantly different from that of school children with parents who never smoked. Passive smoking caused an increase of the BLL only in preschool children in Japan. This is probably because preschool infants spend much more time with their parents and have much more contact with passive smoking than school children and, additionally young infants have a limited ability to excrete lead from the body.     

Determinants of blood lead levels in children: a cross-sectional study in the Canary Islands (Spain)

The adverse effects of lead exposure on children are well known. Low blood lead levels (BLL) produce neurodevelopmental delay and cognitive disorders. However, since BLL thresholds for adverse effects on children's health are not known, the children population at risk of excessive lead exposure still has to be identified. This study was aimed at evaluating BLL in a children population of Gran Canaria (Canary Islands, Spain). Up to our knowledge, this is the first study to report on BLL in this population. Lead was identified and quantified in blood samples of 120 children, by means of Graphite furnace atomic absorption spectrometry (GFAAS). Lead was undetected in 80% of samples; BLL was 1 to 5 μg/dl in 15% of samples, and higher than 5 μg/dl in more than 4% of samples. BLL values in the evaluated children were low and similar to those described for other populations in Western countries. However, samples with the highest contamination (those in percentile 95) reached BLLs as high as 5.2 μg/dl. Positive associations were found between BLL and recent immigration (children adopted from non-western countries), and between BLL and parental smoking in children with low weight at birth. Since lead exposure in childhood may be a causative factor in adverse health trends - especially those involving the neurological system - and since threshold values for adverse lead effects are unknown, our finding that around 20% of the studied children had BLL higher than 1 μg/dl are of concern. Enhancing preventive measures for reducing lead exposure in children from the Canary Islands deserves further study.     

A pilot study of take-home lead exposure in new jersey

Studies in various industries have found an association between worker exposure to lead and elevated blood lead levels in workers' children, but the magnitude of this problem is unknown. In an effort to characterize this problem further, a pilot study was undertaken to obtain blood lead levels of children of lead-exposed workers with elevated blood lead levels who had been reported by laboratories to the New Jersey Department of Health. Fifteen workers' families participated in this study, including 28 children. Thirty-two percent of the children were found to have blood lead levels ≧ 10 μg/dl, the level of concern set by the Centers for Disease Control and Prevention for medical monitoring. This finding is in contrast to population-based data collected from the Third National Health and Nutrition Survey, where the overall prevalence of blood lead levels ≧ 10 μg/dl was only 4.5%.     

Comparison of the entropy technique with two other techniques for detecting disease clustering using data from children with high blood lead levels

The entropy technique was compared with two other case-control techniques for detecting disease clustering using data on blood lead levels of children who were patients at the King/Drew Medical Center in South-Central Los Angeles in 1991 to 1994. The other two methods are the nearest neighbor technique (NNT) and Moran's IPOP technique, a variation of Moran's I test, in which rates are adjusted for population size. Four different blood lead levels (15 microg/dl, 20 microg/dl, 30 microg/dl, 35 microg/dl) were used as cutoff levels to designate cases. Persons with blood lead levels greater than or equal to the cutoff level were designated as cases. The authors found significant clustering for all four cutoff levels using the entropy method, and for the first three cutoff levels using the NNT. They found significant clustering with Moran's IPOP for some scales for two of the cutoff levels. While performance of the entropy technique and the NNT were independent of scale, that of Moran's IPOP was highly scale-dependent.     

Public Protection in an Open Exhibit of Radioactivity

Studies on the effects of lead on the somatic growth of children are limited and contradictory. The authors investigated the adverse effects of blood lead concentration on the somatic growth of primary-school-age children. In this study, there was a total of 522 children, aged 6–9 y, who resided in three areas of Greece (i.e., Loutraki, Lavrion, and Elefsina). The medical evaluation included medical history; physical examination; and measurements of height, head circumference, and chest circumference. The authors also evaluated dietary information, socioeconomic status, and height of parents. The authors conducted laboratory tests for hematological parameters and blood lead levels. The mean blood lead level was 12.3 μg/dl (standard deviation = 8.9 μg/dl), and levels ranged from 1.3 μg/dl to 51.2 μg/dl. There were negative monotonic relationships between growth parameters and blood lead levels, even after the authors allowed for confounding effects. An increase in blood lead level of 10 μg/dl was associated with a decrease of (a) 0.33 cm in head circumference (95% confidence interval = 0.12, 0.55; p = .002); (b) 0.86 cm in height (95% confidence interval = 0.14, 1.16; p = .020); and (c) 0.40 cm in chest circumference (95% confidence interval = ?0.22, 1.02; p = .207). These findings led the authors to conclude that a decrease in growth in children may be associated with blood lead concentrations.     

Air lead pollution and lead exposure of experimental animals and children in Stara Zagora town (Bulgaria)

The air pollution with lead aerosols in Stara Zagora town was investigated at four sampling sites over a period of 6 years. Transport is the main source of air lead pollution in the town. The mean annual air lead concentrations varied from 0.06 to 0.6 μg/m³. The highest air lead levels were measured in the area of a big crossroads during the whole period. An experimental group of mice were exposed near to the crossroads and a control group was exposed in a relatively cleaner residential district for 6 months. The lead concentrations in blood, urine, bones, kidney, liver and lung investigated by atomic absorption spectrometry were significantly higher in the animals from the experimental group in comparison with the control. The lead levels in blood, urine and nails were investigated in children living and going to school in the area with high transport traffic and in a control group of children from the residential district where the control mice were exposed. The mean blood lead level estimated in the group of children exposed at the higher air lead pollution (10.28 μg/dl) slightly exceeded this estimated in the control group (9.47 μg/dl) and the standard for childhood of the Center for Disease Control and Prevention, US (10 μg/dl). It was found that 60% of children from the 'experimental' and 50% from the control group had PbB concentrations equal to or higher than the lowest limit action level. Lead levels in urine were significantly higher in the 'experimental' group as a whole, and in the 'female experimental' group of children also.     

广州市某医疗机构体检儿童血铅水平调查

[目的]调查广州市0～14岁儿童血铅水平,为防治儿童铅中毒提供科学依据。[方法]收集2010年1月至2011年6月在广东省中医院就诊的0～14岁儿童1517名血铅资料,按照年龄划分为3组：〈3岁、3～7岁及〉7岁儿童组。采用原子吸收光谱法测定血铅含量。[结果]0～14岁儿童血铅均值为57.05μg/L;血铅≥100μg/L者39例,占调查人数的2.57%。不同年龄组间儿童血铅水平差异有统计学意义（P〈0.05）;3～14岁年龄段男童血铅水平明显高于女童（P〈0.05）。[结论]本次调查儿童血铅水平及铅中毒率较低。但铅对儿童健康的潜在风险不能忽视,应加强儿童铅中毒防治健康教育。     

Evaluation of lead levels in children living near a Los Angeles county battery recycling facility.

This cross-sectional study examined the association between environmental lead measurements surrounding a Los Angeles County battery recycling facility and the blood lead levels of the children living nearby. Environmental lead measurements and blood lead levels of young children living in a community adjacent to a stationary lead source were compared to those living in a community without a stationary lead source. Predictors of blood lead level were identified. The blood lead levels of the children living near the secondary lead smelter were within the normal range (< 5 micrograms/dl). The absence of ground cover was associated with slightly increased blood lead levels; however, this increase was not of biological significance. Lead levels in surface soil near the stationary lead source were elevated compared to the control community; however, the soil affected community, which may be due in part to controls recently installed at the stationary lead source.     

Blood Lead Secular Trend in a Cohort of Children in Mexico City. II. 1990–1995

The authors determined the secular trend in blood lead levels in a cohort of 91 children born in Mexico City between 1987 and the beginning of 1993. The authors grouped children by calendar year in which they reached 36 mo of age (i.e., 1990–1995), and their blood lead levels were measured every 6 mo during a 66-mo period. The overall geometric mean blood lead level was 8.6 μmlg/dl (range = 1.0–61.0 μmlg/dl). A repeated measures analysis of variance revealed a significant downward linear trend in blood lead levels by year (p < .001)—from an estimated marginal geometric mean of 14.2 μmlg/dl in 1990 to 6.3 μmlg/dl in 1995. There was also a significant linear age effect (p < .001); blood lead levels generally fell during the 36th-66th mo. Family use of lead-glazed pottery significantly elevated blood lead levels (p = .006), and the effect magnified as age increased (Age x Pottery Interaction [p = .014]). Although the overall downward trend in blood lead levels during the time period described corresponded to a reduction in various sources of lead exposure, there was no alteration in production, distribution, or use of leaded pottery. Currently, use of lead-glazed ceramic pottery is one of the most profound sources of lead exposure in the Mexican population.     

Determinants of Blood Lead Levels across the Menopausal Transition

In this study, the authors sought to evaluate the impact of menopause on lead remobilization from bone-lead stores. The study was conducted between 1993 and 1995 in Mexico City and included 903 women (mean age = 46.8 y [standard deviation = 8.2 y]). Participants provided information about reproductive variables and known risk factors for high PbB levels. PbB levels were determined with graphite furnace atomic absorption spectrophotometry. The authors used linear-regression models to describe the relationship between PbB levels and variables of interest. PbB levels ranged from 1.0 μg/dl to 43.8 μg/dl (mean = 11.0 μg/dl). Menopausal women at baseline had the highest PbB levels; the mean difference between pre- and postmenopausal women was 0.76 μg/dl (95% confidence interval = 0.024, 1.48). We observed an inverted U-shaped relationship between PbB level and age. The highest PbB levels were observed in women aged 47-50 y. Other important predictors of PbB levels were use of lead-glazed ceramics, number of pregnancies, history of cigarette smoking, and height. Our results support the hypothesis that bone lead may be mobilized during menopause and may constitute an important source of exposure.     

Blood lead levels of 4-11-year-old Mexican American, Puerto Rican, and Cuban children

Data from the Hispanic Health and Nutrition Examination Survey were used to estimate arithmetic mean blood lead and percent with elevated blood lead [25 micrograms per deciliter (micrograms per dl) or greater] for 4-11-year-old Mexican American, Puerto Rican, and Cuban children. The sample size was 1,390 for Mexican American children, 397 for Puerto Rican children, and 114 for Cuban children. Puerto Rican children had the highest mean blood lead levels (11.5 micrograms per dl), followed by Mexican American children (10.4 micrograms per dl) and Cuban children (8.6 micrograms per dl, P less than .05). Puerto Rican children had the highest percent with elevated blood lead (2.7 percent); 1.6 percent of Mexican American children had elevated blood lead; less than 1 percent (0.9 percent) of the Cuban children had elevated blood lead (P less than .05). Mexican American girls had a lower mean blood lead level than did boys: 9.7 micrograms per dl versus 11.0 micrograms per dl (P less than .05). For both Puerto Rican and Mexican American children, younger age indicated a higher risk of having elevated blood lead levels. Mexican American children who lived in poverty had higher mean blood lead levels than did Mexican American children who did not live in poverty--11.6 micrograms per dl versus 9.6 micrograms per dl (P less than .05). Despite advances in primary prevention of lead toxicity in children during the past 10 years, many Hispanic children are at risk of lead toxicity. Approximately 19,000 Mexican American 4-11-year-old children living in the Southwest and approximately 8,000 Puerto Rican children living in the New York City area had elevated blood lead levels (greater than or equal to 25 micrograms per dl) during 1982-84.