Geometric Mean Blood Lead Levels Research Articles

Seasonality and trend in blood lead levels of New York State children.

BackgroundEnvironmental exposure to lead remains a significant health problem for children. The costs of lead exposure in children are estimated to be considerably more than other childhood diseases of environmental origin. While long-term trends in blood lead levels (BLLs) among children are declining, seasonal variation persists. Cross-sectional studies have found a peak in summer months. Part of this variation may be due to increased exposure to lead paint on window sills and through increased contact with soils containing lead during the summer. The current study represents the largest published population-based study on seasonality and trends in the BLLs of children to date. In addition, the results offer a comparison of recent data on seasonality of BLLs in New York State children, to studies conducted over the past three decades.Methods262,687 New York State children born between 1994 and 1997 were screened for blood lead within 2 weeks of their first or second birthdays. Time series analyses of blood lead data from these children were conducted to study the seasonality and trends of BLLs.ResultsChildren's blood lead values showed a distinct seasonal cycle on top of a long-term decreasing trend. The geometric mean BLL declined by about 24% for children born between 1994 and 1997. The prevalence of elevated BLLs in two-year-olds was almost twice that in one-year-olds over the time period. Nearly twice as many children had elevated BLLs in the late summer compared to late winter/early spring. In this and previous cross-sectional studies, the amount of seasonality as a proportion of the mean ranged between 15% and 30%.ConclusionPediatricians should be aware of the seasonality of BLLs. For example, if a two-year-old receives a borderline result during the winter, it is possible that the levels would have been higher if he had been tested during the summer. However, physicians should continue to screen children at their normally scheduled well-child visits rather than delaying until summertime and possibly postponing the discovery of an elevated BLL. Age, season, and time trends still need to be considered in lead studies and result interpretation.

Assessment of lead exposure and associated risk factors in urban children in Silesia, Poland

A program of childhood lead poisoning prevention was conducted in six cities of Silesia, the most industrialized region of Poland. We analyzed records of 11,877 children aged 24–84 months, tested between 1993 and 1998, to assess children's exposure to lead and associations of blood lead levels (BLL) with season of sampling, questionnaire data, and environmental levels of lead. Air lead concentrations and lead fallout, as measured in the ambient air monitoring system, were below current Polish air quality standards and gradually decreased. The geometric mean (GM) BLL was 6.3 μg/dL (range from 0.6 to 48 μg/dL), and >13% of children had BLL ⩾10 μg/dL. Mean BLL declined from 6.8 μg/dL in 1993–1994 to almost 5.5 μg/dL in 1998. GM BLL in spring and summer (‘nonheating’ season) months were 10% higher than BLL in children tested in fall and winter (‘heating’ season), although air lead concentrations were lower in nonheating and higher in the heating season. For both the heating and nonheating seasons, there was a significant increase in the mean BLL with increasing air lead concentrations. Poor housing (odds ratio (OR): 1.82; 95% CI: 1.4, 2.3), two or more siblings in the family (OR: 3.12; 95% CI: 2.6, 3.7), lack of recreational trips outside the region (OR: 1.66; 95% CI: 1.47, 1.89), and the time child spent outdoors were associated with elevated BLL. Variables found to affect BLL in the Silesian children should be used to propose criteria to improve identification of children at risk and to focus prevention activities more effectively.

Indirect lead exposure among children of radiator repair workers.

Secondary exposure to lead has been identified as a public health problem since the late 1940s; we investigate the risk of lead exposure among families of radiator repair workers. A sample of the wives and children, aged 6 months to 6 years (exposed children) (n = 19), of radiator repair workers and a sample of children whose parents were not occupationally exposed to lead (non-exposed children) (n = 29) were matched for age and residence; their geometric mean blood lead levels are compared. Blood samples were obtained by the finger stick method and environmental dust samples by the wipe method; both were analyzed using a portable anodic stripping voltameter. Dust lead levels were significantly higher in the houses of exposed children (143.8 vs. 3.9 microg/g; P < 0.01). In crude analyses, the highest lead levels were observed among children whose fathers worked in home-based workshops (22.4 microg/dl)(n = 6). Children whose fathers worked in an external workshop (n = 13) also had high levels (14.2 microg/dl) (P < 0.01), while blood lead levels in non-exposed children were significantly lower (5.6 microg/dl)(P < 0.01). The observed differences remained significant after adjustment for age and gender. This study confirms that children of radiator repair workers are at increased risk of lead exposure and public health interventions are needed to protect them.

The effect of lead-based paint hazard remediation on blood lead levels of lead poisoned children in New York City

Despite the widespread use of lead paint hazard control for children with lead poisoning, few controlled studies that estimate the effect of such control on children's blood lead levels have been published. This retrospective follow-up study examined the effects of lead hazard remediation and its timing on the blood lead levels of lead-poisoned children. From the New York City child blood lead registry, 221 children were selected who had an initial blood lead level of 20–44μg/dL between 1 July 1994 and 31 December 1996; were 6 months to 6 years of age; had a report of a follow-up blood lead test between 10 and 14 months after the initial test; had a lead-based paint hazard identified in the primary dwelling unit prior to the 10- to 14-month follow-up blood lead test; had resided or spent time at only one address with an identified lead-based paint hazard; and were not chelated. The decline in geometric mean blood lead levels from baseline to 10–14 months later was compared for children whose homes were remediated and whose homes were not remediated during the follow-up period. Regardless of remediation, geometric mean blood lead levels declined significantly from 24.3μg/dL at the initial diagnosis to 12.3μg/dL at the 10- to 14-month follow-up blood lead test (P<0.01). Among the 146 children whose homes were remediated the geometric mean blood lead levels declined 53% compared to 41% among the 75 children whose homes were not remediated by the follow-up blood lead test, a remediation effect of approximately 20% (P<0.01). After adjusting for potential confounders, the remediation effect was 11%, although it was no longer significant. Race was the only factor that appeared to confound the relationship: Black children had higher follow-up blood lead levels even after controlling for other factors, including the natural logarithm of the initial blood lead level. The effect of remediation appeared to be stronger for younger (10 to <36 months old) than for older (36 to 72 months old) children (P=0.06). While children in homes with earlier remediation (within less than 3 months) appeared to have greater declines in blood lead levels at the follow-up test than children in homes with later remediation (after 3 or more months), this trend was not significant when controlling for confounding factors. The findings of this study suggest that early identification of lead-poisoned children and timely investigation and abatement of hazards contribute to reducing blood lead levels. However, the apparent effect is modest and further research is needed to systematically test and improve the effectiveness of lead hazard controls.

Niveles de plomo en sangre y factores de exposición en niños del estado de Morelos, México

To assess blood lead levels and lead exposure factors in children living in Morelos State, Mexico. A cross-sectional study was conducted between June and October 1996, in 232 children aged 1-12 years, at Hospital del Niño Morelense de Cuernavaca, Morelos, Mexico. Blood lead levels were measured by anodic voltameter, and exposure factors were collected by questionnaire. The lead concentration value was log transformed for statistical analysis. Odds ratios were obtained for some risk factors. The statistical significative risk factors were later analyzed with ANOVA. A total of 232 children were recruited (50% female); 73% resided in Cuernavaca City. The geometric mean blood lead level was 6.7 micrograms/dl; 29.7% of the children had levels over 10 micrograms/dl; 66% reported use of lead glazed pottery for cooking, 36% for storing food, and 19% for drinking. Blood lead levels were similar to those reported in other Mexican children studies, after the reduction of lead in gasoline. The main risk factors were use of lead glazed pottery and vehicle traffic intensity near the household. These results will be useful for future prevention and control interventions. This paper is available too at: http://www.insp.mx/salud/index.html.

Blood lead levels and risk factors for lead poisoning among children in Jakarta, Indonesia

The phase-out of leaded gasoline began in Jakarta, Indonesia on July 1, 2001. We evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs of Jakarta school children and assessed risk factors for lead exposure in these children before the beginning of the phase-out activities. The study involved a population-based, cross-sectional blood lead survey that included capillary blood lead sampling and a brief questionnaire on risk factors for lead poisoning. A cluster survey design was used. Forty clusters, defined as primary schools in Jakarta, and 15 2nd- and 3rd-grade children in each cluster were randomly selected for participation in the study. The average age of children in this study was 8.6 years (range 6–12) and the geometric mean BLL of the children was 8.6 μg/dl (median: 8.6 μg/dl; range: 2.6–24.1 μg/dl) ( n=397). Thirty-five percent of children had BLLs ≥10 μg/dl and 2.4% had BLLs ≥20 μg/dl. Approximately one-fourth of children had BLLs 10–14.9 μg/dl. In multivariate models, level of education of the child's primary caregiver, water collection method, home varnishing and occupational recycling of metals, other than lead, by a family member were predictors of log BLLs after adjustment for age and sex. BLLs of children who lived near a highway or major intersection were significantly higher than those of children who lived near a street with little or no traffic when level of education was not included in the model. Water collection method was a significant predictor of BLLs ≥10 μg/dl after adjustment for age and sex. BLLs in children in this study were moderately high and consistent with BLLs of children in other countries where leaded gasoline is used. With the phase-out of leaded gasoline, BLLs of children in Jakarta are expected to rapidly decline as they have in other countries that have phased lead out of gasoline.

Further Comparisons of Empirical and Epidemiological Data with Predictions of the Integrated Exposure Uptake Biokinetic Model for Lead in Children

Observed blood lead levels for young children from several communities are compared with blood lead levels predicted for those communities using the USEPA's Integrated Exposure Uptake Biokinetic (IEUBK) Model. In contrast to the compari sons described elsewhere, the blood lead levels observed in the communities con sidered here are not well represented by the model's predictions. The model's predictions for Midvale, UT; Sandy, UT; Cincinnati, OH; and a recent data set for Palmerton, PA, show considerable deviation from observation both for the geometric mean blood lead level and the percent of blood lead levels above 10 µg/dL. Various adjustments in the model to consider play area soils, site specific geometric standard deviations and the time children spend away from their homes do not substantially improve the comparisons to observation. It is difficult to predict a priori the data sets for which the model will yield adequate predictions. This reduces the value of the model for use in communities where blood lead measurements have not been made, and suggests that caution should be exercised when using the model to set soil lead cleanup levels or to predict the result of remediation.

Iron deficiency associated with higher blood lead in children living in contaminated environments.

The evidence that iron deficiency increases lead child exposure is based primarily on animal data and limited human studies, and some of this evidence is contradictory. No studies of iron status and blood lead levels in children have accounted for environmental lead contamination and, therefore, the source of their exposure. Thus, no studies have directly determined whether iron deficiency modifies the relationship of environmental lead and blood lead. In this study, we compared blood lead levels of iron-deficient and iron-replete children living in low, medium, or highly contaminated environments. Measurements of lead in paint, soil, dust, and blood, age of housing, and iron status were collected from 319 children ages 1-5. We developed two lead exposure factors to summarize the correlated exposure variables: Factor 1 summarized all environmental measures, and Factor 2 was weighted for lead loading of house dust. The geometric mean blood lead level was 4.9 microg/dL; 14% exceeded 10 microg/dL. Many of the children were iron deficient (24% with ferritin < 12 ng/dL). Seventeen percent of soil leads exceeded 500 microg/g, and 23% and 63% of interior and exterior paint samples exceeded 5,000 microg/g. The unadjusted geometric mean blood lead level for iron-deficient children was higher by 1 microg/dL; this difference was greater (1.8 microg/dL) after excluding Asians. Blood lead levels were higher for iron-deficient children for each tertile of exposure as estimated by Factors 1 and 2 for non-Asian children. Elevated blood lead among iron-deficient children persisted after adjusting for potential confounders by multivariate regression; the largest difference in blood lead levels between iron-deficient and -replete children, approximately 3 microg/dL, was among those living in the most contaminated environments. Asian children had a paradoxical association of sufficient iron status and higher blood lead level, which warrants further investigation. Improving iron status, along with reducing exposures, may help reduce blood lead levels among most children, especially those living in the most contaminated environments.

Blood Lead Levels among Children Aged 1 to 5 Years in Wuxi City, China

The objective of this study was to determine mean blood lead levels and prevalence of elevated blood lead levels among 1- to 5-year-old children in Wuxi City, China. By use of a representative cross-sectional survey that included measurements of capillary blood lead, 1117 children aged 1–5 years were examined from October through December, 1997. The geometric mean blood lead level for children 1–5 years of age in Wuxi City was 8.2 μg/dL (0.40 μmol/L); 27.3% had blood lead levels ≥10 μg/dL and 1.0% had blood lead levels ≥20 μg/dL. Blood lead levels were significantly higher for males and for those living in industrial areas, particularly the Beitang, Mashan, and Xinqu districts. Residence in these districts and in the Jiaoqu industrialized district also increased the likelihood of an elevated blood lead level, with odds ratios ranging from 2.59 to 4.53. In conclusion, blood lead levels among Wuxi City children are high enough to be of concern, particularly in industrial areas. Further studies are needed to better define the extent of lead exposure among children in China. In addition, national standards for blood lead collection and measurement methods should be applied in China.

Lead levels in blood bank blood.

Although blood bank blood is usually screened for dangerous pathogens, the presence of toxic metals in blood has received little attention. Population blood lead levels have been declining in the United States, but occasional high outliers in blood lead concentration can be found--even when mean levels of blood lead are low. We sampled 999 consecutive blood bank bags from the King/Drew Medical Center, used between December 1999 and February 2000. The geometric mean blood lead level was 1.0 microg/dl (0.048 micromol/l), but 0.5% of the samples had lead levels that exceeded 10 microg/dl, and 2 samples had lead levels that exceeded 30 microg/dl. The 2 samples with the highest lead levels could have presented an additional risk to infants if they were used for blood replacement. Therefore, even in countries with generally low population blood lead levels, blood bank blood should be screened for lead concentration prior to use with infants.

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 microg/dl (range = 1.0-61.0 microg/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 microg/dl in 1990 to 6.3 microg/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.

Lead-glazed ceramic ware and blood lead levels of children in the city of Oaxaca, Mexico.

Although Mexico substantially reduced use of leaded gasoline during the 1990s, lead-glazed pottery remains a significant source of population exposure. Most previous studies of lead in nonoccupationally exposed groups in Mexico have been conducted in the Mexico City metropolitan area. Oaxaca, a poor southern state of Mexico, has a centuries-old tradition of use of low temperature lead-glazed ceramic ware manufactured mainly by small family businesses. We measured blood lead levels in 220 8-10-y-old children (i.e., not from pottery-making families) who were students in the innercity of Oaxaca and in the mothers of all children. The geometric mean blood lead level of the children was 10.5 microg/dl (+7.0/-4.3 microg/dl standard deviation; range = 1.3-35.5 microg/dl). The corresponding mean value for the mothers was 13.4 (+9.0/-5.4 microg/dl standard deviation; range = 2.8-45.3 microg/dl). We used cutoffs that were greater than or equal to 10 microg/dl, 20 microg/dl, and 30 microg/dl, and we determined that 54.9%, 10.3%, and 3.0% of the children were at or above the respective criteria. We accounted for 25.2% of the variance in blood lead levels of the children, using maternal responses to a questionnaire that assessed possible lead sources in a linear multiple-regression model. The most important factors related to lead levels were family use of lead-glazed pottery, use of animal fat in cooking, and family income. The addition of maternal blood lead level to the model increased accounted variance in blood lead to 48.0%. In logistic-regression modeling of children's blood lead levels, we used a cutoff of greater than or equal to 10 microg/dl, and we found that use of lead-glazed pottery was the most important of all questionnaire items that were predictive of blood lead levels (odds ratio = 2.98). In Oaxaca, as is the case elsewhere in Mexico, lead-glazed ceramic ware remains a significant risk factor for elevated blood lead levels in children.

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 μg/dL (0.4 to 38.7) and 2.8 μg/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 μg/g (−33.7 to 62.2) and 8.4 μg/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.

Blood lead levels among children of lead-exposed workers: A meta-analysis

To further assess the utility of targeted blood lead screening for children from households with members having occupational lead exposures, we conducted a meta-analysis of all available reports of take-home lead exposures. Our objective was to estimate the blood lead levels among U.S. children (ages 1-5) from households with lead-exposed workers. Reports considered for inclusion were cited in Medline, Toxline, Excerpta Medica, and Bio-Med plus all unpublished reports available at the National Institute for Occupational Safety and Health through 1994. The a priori criteria for inclusion of U.S. reports required their having data on: (1) venous blood lead levels for children, (2) children's ages, (3) data for at least five children, (4) workers' occupations, (5) workers' blood lead levels, and (6) data collection methods. Based on a meta-analysis of 10 reports from 1987 through 1994, the children (n=139) of lead-exposed workers (n=222) had a geometric mean blood lead level of 9.3 microg/dL compared to a U.S. population geometric mean of 3.6 microg/dL (P=0.0006). Also in this group, 52% of the children had blood lead levels (BLLs) >/= 10 microg/dL compared to 8.9% in the U.S. (P=.0010), and 21% of the children had BLLs >/= 20 microg/dL compared to 1.1% in the U.S. (P=. 0258). We estimate, based on 1981-83 survey data, that there are about 48,000 families with children under six living with household members occupationally exposed to lead. If the findings from this meta-analysis (admittedly limited by small numbers) are generalizable, about half of the young children in these families may have BLLs >/= 10 microg/dL. Data were too sparse to determine if children of workers with elevated blood leads were at greater risk than children whose parents were only known to be lead exposed. Our findings support the position that children of lead-exposed workers should be targeted for blood lead screening. Am. J. Ind. Med. 36:475-481, 1999. Published 1999 Wiley-Liss, Inc.

Secular trend in blood lead levels in a cohort of Mexico City children.

We determined the secular trend in blood lead levels in a cohort of 104 children born in Mexico City between 1987 and 1993. We grouped children by the calendar year in which they reached 6 mo of age and measured blood lead levels every 6 mo until they attained 36 mo of age. The overall geometric mean blood lead level was 9.6 microg/dl (range = 1.5-59.5 microg/dl). A repeated measures analysis of variance revealed a highly significant linear trend in blood lead level with year (p < .001); there was a maximum decrease of 7.6 microg/dl between 1989 and 1993. There was a highly significant quadratic age effect (p < .001); blood lead levels rose between 6 and 18 mo of age and decreased thereafter. There was a marginally significant interaction between age of the child and year. Family use of lead-glazed pottery significantly elevated blood lead levels (p = .028). The downward trend in blood lead levels during the time period of study corresponded to the reduction in various sources of lead exposure.

New lead screening guidelines from the Centers for Disease Control and Prevention: how will they affect pediatricians?

In October 1991, the Centers for Disease Control and Prevention (CDC) issued lead screening guidelines1 that 1. Recommended blood lead screening for virtually all 1-year-old children and, when resources permit, for all 2-year-old children as well; 2. Suggested five questions that physicians could use to assess whether an individual child might be at risk for lead poisoning; 3. Offered recommendations regarding further testing and follow-up should a blood lead level (BLL) ≥10 μg/dL be found. In 1993, the American Academy of Pediatrics (AAP) published recommendations2 similar to those of the CDC. Both sets of recommendations were influenced by reports demonstrating adverse neuropsychologic effects from BLLs as low as 10 μg/dL3,4and by data from the second National Health and Nutrition Examination Survey (NHANES II), conducted 1976–1980, showing that 88% of 1- to 5-year-old children had BLLs ≥10 μg/dL.5,6 Subsequent to publication of the 1991 CDC and 1993 AAP guidelines, data from a number of blood lead screening studies demonstrated marked variation in the prevalence of elevated BLLs.7-12Publication of data from these studies, many appearing in the February 1994 issue of this journal, resulted in a commentary in the same issue that questioned the appropriateness of the CDC screening and follow-up recommendations.13 Variation in the prevalence of children with BLLs ≥10 μg/dL ranged from 71% in central Philadelphia9 and 28% in central Rochester8 to 3.6% in Chicago suburbs7 and 0.6% in Alaska Medicaid children.10 In the Chicago area study, 0.1% of children had a BLL ≥20 μg/dL, and in Alaska none had a BLL ≥11 μg/dL. Results of Phase I (1988–1991) of NHANES III, which were unavailable when the 1991 CDC guidelines were developed, showed a marked reduction in the geometric mean (GM) BLL of 1- to 5-year-old children …

Statewide assessment of lead poisoning and exposure risk among children receiving Medicaid services in Alaska.

Lead poisoning is a well-recognized public health concern for children living in the United States. In 1992, Health Care Financing Administration (HCFA) regulations required lead poisoning risk assessment and blood lead testing for all Medicaid-enrolled children ages 6 months to 6 years. This study estimated the prevalence of blood lead levels (BLLs) >/=10 microg/dL (>/=0.48 micromol/L) and the performance of risk assessment questions among children receiving Medicaid services in Alaska. Measurement of venous BLLs in a statewide sample of children and risk assessment using a questionnaire modified from HCFA sample questions. Eight urban areas and 25 rural villages throughout Alaska. Nine hundred sixty-seven children enrolled in Medicaid, representing a 6% sample of 6-month- to 6-year-old Alaska children enrolled in Medicaid. Determination of BLL and responses to verbal-risk assessment questions. BLLs ranged from <1 microg/dL (<0.048 micromol/L) to 21 microg/dL (1.01 micromol/L) (median, 2.0 microg/dL or 0.096 micromol/L). The geometric mean BLLs for rural and urban children were 2.2 microg/dL (0.106 micromol/L) and 1.5 microg/dL (0.072 micromol/L), respectively. Six (0.6%) children had a BLL >/=10 microg/dL; only one child had a BLL >/=10 microg/dL (11 microg/dL or 0.53 micromol/L) on retesting. Children whose parents responded positively to at least one risk factor question were more likely to have a BLL >/=10 microg/dL (prevalence ratio = 3.1; 95% confidence interval = 0.4 to 26.6); the predictive value of a positive response was <1%. In this population, the prevalence of lead exposure was very low (0.6%); only one child tested (0.1%) maintained a BLL >/=10 microg/dL on confirmatory testing; no children were identified who needed individual medical or environmental management for lead exposure. Universal lead screening for Medicaid-enrolled children is not an effective use of public health resources in Alaska. Our findings identify an example of the importance in considering local and regional differences when formulating screening recommendations and regulations, and continually reevaluating the usefulness of federal regulations.

Results of a lead decontamination program.

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 micrograms/dl (0.44 mu mol/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 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 micrograms/dl (0.24 mu mol/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.

Blood lead levels in North Carolina painters.

1. Blood lead levels were examined in 127 housepainters in North Carolina between April and September, 1993. Each participant filled out a questionnaire and gave a blood sample. The questionnaire covered the individual's work history, concentrating on paint-removal activities and personal protection, and also covered potential nonoccupational sources of lead exposure. Blood samples were analysed for lead content using atomic absorption spectroscopy. 2. The geometric mean blood lead level was 0.33 mumol L-1 (6.8 micrograms dL-1). No blood lead samples were found to exceed the occupational standard of 1.93 mumol L-1 (40 micrograms dL-1). The three highest samples had levels between 0.97 and 1.45 mumol L-1 (20 and 30 micrograms dL-1); this represented 2.4% of the study sample. 3. No statistical association was found between blood lead levels in these painters and their painting activities, including using dust masks for personal protection. 4. Current painting practices in this group of North Carolina painters do not appear to elevate blood lead levels above the occupational standard.

Time Trend and Determinants of Blood Lead Levels in a Swiss Population over a Transition Period (1984-1993) from Leaded to Unleaded Gasoline Use

This study analyzes the trend and determinants of blood lead levels in a Swiss region (population 770,000) over the 10-year period following the introduction of unleaded gasoline in 1985. The consumption of unleaded fuel increased rapidly, accounting in 1988 for 36% and in 1992 for 65% of all gasoline sales. Blood lead levels were measured in three representative samples ( n = 1700) of the adult population within the framework of a health examination survey carried out in 1984/1985, 1988/1989, and 1992/1993. The geometric mean blood lead levels were, respectively, 0.59, 0.42, and 0.33 μmole/liter in men, 0.41, 0.29, and 0.25 μmole/liter in women. Similar trends have been observed across all age groups, occupational classes, and categories based on smoking, drinking, and dietary habits. The overexposure of city residents, in comparison to village residents, fades out over the observation period. These findings suggest that the changeover from leaded to unleaded gasoline has been the major cause of the blood lead decline. Wine drinking, cigarette smoking, and age appear to be significant determinants of blood lead for both sexes in all three surveys. In contrast, the association is inverse for milk consumption. The multivariate regression analysis shows that wine drinking remains the most important predictor of blood lead, whereas the influence of age increases with time and overcomes the effect of smoking in the third survey.