Soil Lead Levels Research Articles

Environmental and childhood lead contamination in the proximity of boat-repair yards in southern Thailand—I: Pattern and factors related to soil and household dust lead levels

High blood lead levels have recently been documented in schoolchildren living in communities adjacent to boat-repair yards in southern Thailand. In this study, the spatial pattern of lead contamination of soil and household dust in an area surrounding several boat-repair yards is described, and household factors associated with elevated dust lead are identified. A cross-sectional spatial study was conducted in a coastal residential area within a distance of 2 km from three major boat-repair yards situated on the east coast of peninsular Thailand. Household dust specimens were collected from an undisturbed position in the residences of children, aged 4–14 years, sampled randomly from all children living in the study area. Soil specimens were obtained from the interstices of a square grid, 70×70 m 2, superimposed on the area. Geographic coordinates of residence and soil sampling positions were recorded and semivariograms and kriging used to contour the spatial distribution of lead in dust and soil. Environmental lead levels were also modeled in terms of direction and minimum distance from a boat-repair yard and, for household dust lead content, in terms of household variables, including occupation of household members in boat-repair work, type of house construction, and general cleanliness. Household dust and soil lead content ranged from 10 to 3025 mg/kg and from 1 to 7700 mg/kg, respectively. The distribution of soil lead peaked at the location of the boat-repair yards, but outside the yards the distribution was generally below 400 mg/kg and irregular. About 24% of household dust lead specimens were equal to or above 400 mg/kg, but showed significant decrease with increasing distance from the boat-repair yards, at rates of between 7% and 14% per 100 m. In houses where a family member was a worker in one of the major boatyards and in houses where occasional repair of small boats was undertaken, household dust lead levels were significantly elevated, by 65% (95% CI: 18–130%) and 31% (95% CI: 5–63%), respectively. Siting of boat-repair yards at a distance from residential areas and measures to reduce the spread of lead-containing dust are recommended to alleviate the problem of elevated household dust lead levels.

Lead and IQ in Children: Lanphear et al. Respond

As described in our original article (Lanphear et al. 2005), we decided a priori to focus our analyses on the blood lead (BPb) variable that had the strongest association with IQ (intelligence quotient) scores. This decision was made to limit the number of analyses and to minimize problems with multiple comparisons. There was a clear consensus among the co-investigators—which originally included Ernhart—to use this strategy. Because concurrent BPb concentration was the strongest predictor of intellectual functioning, we focused most of our analyses on this variable. There are now several studies indicating that concurrent or lifetime average BPb concentration are better predictors of children’s IQ scores than measures taken in early childhood (Baghurst et al. 1992; Canfield et al. 2003; Chen et al. 2005; Dietrich et al. 1993; Tong et al. 1996; Wasserman et al. 2003). Thus, existing evidence indicates that interpretation of this literature should rely on concurrent or lifetime measures of BPb concentration. Ernhart is concerned that we found no significant association of IQ and three of the four indices of lead exposure at peak BPb levels < 10 μg/dL or < 7.5 μg/dL (Lanphear et al. 2005). In addition to a significant inverse association of concurrent BPb concentration and IQ score for children with maximal BPb levels < 7.5 μg/dL, we found a consistent inverse association for lifetime average BPb concentration (β = −3.13, p = 0.054). As we reported, the relationship of peak BPb concentration and early childhood BPb concentration was not as predictive of children’s IQ scores. Ernhart is particularly concerned about our analyses for children with “very low” lead exposure (Lanphear et al. 2005). The results of our parsimonious analysis for children who had maximal BPb concentrations < 10 μg/dL and < 7.5 μg/dL were entirely consistent with the fully adjusted model. When we included all of the additional covariates, concurrent BPb concentration changed by < 5%, and it remained statistically significant (β = −2.99, p = 0.019) for the children with maximal BPb levels < 7.5 μg/dL. When we further restricted the analysis to U.S. cohorts and introduced race as a covariate, race was clearly not a significant factor, and the pattern remained similar. These secondary analyses support our original conclusion that there is an inverse relationship of lead exposure and intellectual function, with greater decrements at lower BPb concentrations (Lanphear et al. 2005). We agree that using an early measure of the HOME (Home Observation for Measurement of the Environment) inventory (Caldwell and Bradley 1984) in the Rochester cohort was a potential limitation. Still, when we excluded the Rochester cohort from the pooled analysis, the coefficient changed by < 3% and remained statistically significant (Lanphear et al. 2005). Thus, this limitation did not alter the conclusions of the study. Ernhart is critical about the “peculiar” increase in sample size and shifts in demographic variables in the Rochester study. Although some families became “too busy” to participate when their children were toddlers, we routinely invited them to participate in subsequent visits. A larger number of families were willing to return for an evaluation as their children aged. We conducted a secondary analysis of studies that included prenatal BPb concentration. Contrary to Ernhart’s comment, prenatal lead exposure was not significantly associated with children’s IQ scores in adjusted analyses (Lanphear et al. 2005). We concluded that “prevention of lead exposure must occur before pregnancy or a child’s birth” (Lanphear et al. 2005) because children are particularly vulnerable to lead intake and absorption during the first 2–3 years of life (Clark et al. 1985; Lanphear et al. 2002; Ziegler et al. 1978). Ernhart argues that her request for further information about the 6-year data from the Rochester study “was denied.” The earlier measures of intellectual function in the Rochester children (i.e., at 3 and 5 years of age) were measured using the Stanford Binet test (Canfield et al. 2003). The IQ test at 6 years of age, which was measured using the Wechsler Preschool and Primary Scales of Intelligence, was done specifically for the pooled analysis. We believed that it was in the best interest of public health to confirm the findings of the original Rochester study with the larger pooled analysis rather than await publication of the follow-up 6-year IQ tests. Numerous studies have found evidence for adverse consequences of childhood lead exposure at BPb levels < 10 μg/dL (Bellinger and Needleman 2003; Chiodo et al. 2004; Fulton et al. 1987; Lanphear 2000; Sood et al. 2001; Walkowiak et al. 1998; Wasserman et al. 2000). These studies provide sufficient evidence that childhood lead exposure should be reduced even more by banning all nonessential uses of lead and further reducing the allowable levels of lead in air emissions, house dust, soil, water, and consumer products.

Sources of Blood Lead in Children

Sources of Blood Lead in Children

The Role of Resuspended Soil in Lead Flows in the California South Coast Air Basin

The inputs and outputs of airborne lead in the South Coast Air Basin of California (SOCAB) are quantified according to standard mass balance calculations. Results for 2001 show that approximately 49,000 kg of lead exitthe Basin each year, but traditional sources contribute only about 6500 kg of lead each year. We resolve this discrepancy through a simple computer model that quantifies the resuspension of lead-containing particles. Our results suggest that these lead particles were deposited during the years of leaded gasoline use and that resuspension is responsible for generating an additional 54,000 kg of airborne lead each year. This agrees roughly with estimated outputs. Thus, we conclude that resuspension, although an insignificant source of airborne lead during the era of leaded fuel, became a principal source in the SOCAB as lead emissions from vehicles declined. The results of the resuspension model further suggest that soil lead levels will remain elevated for many decades, in which case resuspension will remain a major source well into the future.

Lead dust in Broken Hill homes: Effect of remediation on indoor lead levels

This study was undertaken to determine whether home remediation effectively reduced indoor lead levels in Broken Hill, a long-established silver–lead–zinc mining town in outback Australia. A before–after study of the effect of home remediation on indoor lead levels was embedded into a randomized controlled trial of the effectiveness of remediation for reducing elevated blood lead levels in young children. Moist towelettes were used to measure lead loading (μg/m 2) on internal windowsills and internal and entry floors of 98 homes; samples were collected before, immediately after, and 2, 4, 6, 8, and 10 months after remediation. Data were log 10 transformed for the analysis. Remediation reduced average indoor lead levels by approximately 50%, and lead levels remained low for the duration of the follow-up period (10 months). The greatest gains were made in homes with the highest initial lead levels; homes with low preremediation lead levels showed little or no benefit. Before remediation, homes located in areas with high soil lead levels or with “poor” dust proofing had higher lead levels than those in areas with lower soil lead levels or with “medium” or “good” dust proofing; these relative differences remained after remediation. There was no evidence that lead loading was reduced by an increased opportunity to become aware of lead issues. We conclude that remediation is an effective strategy for reducing the lead exposure of children living in homes with high indoor lead levels.

Levels of Lead in Urban Soils from Selected Cities in a Central Region of the Philippines (7 pp)

Levels of Lead in Urban Soils from Selected Cities in a Central Region of the Philippines (7 pp)

Questioning Lead Standards: Even Low Levels Shave Points off IQ

The maximum blood lead concentration deemed acceptable for children has declined over the years, from 60 micrograms per deciliter (μg/dL) in 1970 to the present-day level of 10 μg/dL, first established in 1991. In the last several years, however, researchers have begun to suspect that even lower concentrations may impair cognition. Now a reevaluation of data from seven international longitudinal studies involving 1,333 children confirms this suspicion [EHP 113:894–899]. The studies—conducted in Boston, Cincinnati, Cleveland, Rochester (New York), Port Pirie (Australia), Mexico City, and Yugoslavia—originally looked at children known to be at risk for lead poisoning, such as those living near lead smelters or in deprived urban settings. Therefore, the majority of the participants had blood lead levels far higher than the averages currently being reported in the developed world. The mean blood lead concentration for the entire group peaked at 17.8 μg/dL at age 2.5 years, and declined to 9.4 μg/dL between ages 5 and 7. Only 18% of the children had maximal blood lead levels of less than 10 μg/dL, and 8% had maximal blood lead levels of less than 7.5 μg/dL. Most of the children took IQ tests when they were between almost 5 and 7 years of age; the Boston children were tested at age 10. The current team calculated, across the seven studies, how much of the difference in IQ scores was related to lead alone by controlling for other factors that influence IQ scores, including child birth weight, birth order, prenatal exposure to tobacco smoke and alcohol, and mother’s IQ. On a population basis, an increase in blood lead level from 2.4 to 10 μg/dL at the time of testing was associated with a decrease of 3.9 IQ points. At lower blood lead levels, a small increase in blood lead made a bigger difference in IQ than the same size increase did at higher concentrations. A blood lead level of 20 μg/dL was associated with scoring about 1.9 points lower on tests of IQ compared with a blood lead level of 10 μg/dL. The difference in IQ shrank to 1.1 points when comparing a blood lead level of 20 μg/dL with a concentration of 30 μg/dL. To determine if the data from one particular study drove the final results, the team removed the findings for one site at a time and recalculated the results. It became clear that no single study was driving the results of the pooled analysis. Consistent with a study published in the May 2005 issue of EHP, blood lead level at the time of IQ testing was generally a stronger predictor of effects on IQ than was—as previously believed—blood lead level at age 2. The individual-level effect on IQ is difficult to determine, however, and may depend in part on the child’s social environment. In the United States, about 2–3% of children have a blood lead concentration above 10 μg/dL, but in some cities, such as Rochester, 1 in 5 children have elevated blood lead. These new findings, along with those from previous human and animal studies, point to the importance of eliminating nonessential uses of lead and lowering allowable levels of lead in air emissions, house dust, soil, water, and consumer products.

Characterization of lead and arsenic contamination at Barber Orchard, Haywood County, NC

Barber Orchard is a residential community in Western North Carolina that was declared a U.S. EPA Superfund Site in September 2001 because of elevated levels of arsenic, lead, and organochlorine compounds in the soil. The contamination was introduced by pesticides (e.g., lead arsenate, DDT) when the land was employed as an apple orchard. Concentration levels of lead and arsenic in soil were measured throughout two plots by inductively coupled plasma optical emission spectrometry. A linear relationship was observed between the moles of lead and arsenic. Sequential extraction procedures were employed to characterize the mobility and bioavailability of the metals. The major forms of both elements were bound to iron–manganese oxides. In general, the relative composition of the metal species did not statistically vary with depth, although higher concentration levels were observed near the surface. Brake ferns ( Pteris vittata) were employed in greenhouse phytoremediation experiments employing soil which had been homogenized to a uniform concentration level. Considerable variation was observed in the amount of arsenic absorbed by the ferns.

Lead in Paint and Soil in Karnataka and Gujarat, India

Blood lead surveys in several areas of India have found very high percentages of children with elevated blood lead levels. Fifty-three percent of children under 12 years of age in a seven-city screening had blood lead levels equal to or greater than 10 μg/dL, the level currently considered elevated by the U.S. Centers for Disease Control and Prevention (CDC). A number of these surveys focused on populations near lead smelters or in areas with high lead levels from combustion of lead-containing gasoline. There is little information available, however, on the levels of lead in paint in India and in soil. Field portable X-ray fluorescence analyzers were used to determine environmental lead levels in paint, dust, air, soil, and other bulk samples near several lead-using industries and in the residential environments of children with very high blood lead levels, at least four times as high as the CDC limit. Soils near industrial operations, such as secondary lead smelters, and battery dismantling units contained levels up to 100,000 ppm of lead. Four of 29 currently available paints from five manufacturers measured 1.0 mg/cm 2 or above—the current U.S. definition of lead-based paint in housing—after the application of a single coat; four others measured at least 1.0 after three coats, and three others likely to have reached this level after the application of an additional one or two coats. In five of 10 homes of the elevated blood lead children, three or more locations in or around the home were found to have lead paint levels of 1.0 mg/cm 2 or higher. Soil exceeding the U.S. standard for residential areas (400 ppm) was found at only one of the houses. Other sources of lead exposure, including traditional ayurvedic medicine tablets, were also observed. Similar surveys would be useful elsewhere in India and in other developing countries.

Influence of soil lead (Pb) levels on fungal occurrence, growth and sporulation

The emission of exhaust fumes into the environment, which are eventually deposited in to soils, contributes to the increasing hazardous levels of lead in the soil ecosystem. Kenya has a high number of automotives that emit high levels of exhaust fumes that make lead a major environmental pollutant. At high levels, lead has adverse effect on the soil microbiota. This study was designed to investigate the effect of lead on mucoraceous fungi in a roadside habitat. Mucoraceous fungi are mostly saprophytes and play an important role in nutrient cycling, elemental storage and transport in the soil. Soil plate and dilution methods were used to isolate fungi from the topsoil collected from the Kiambu roadside habitat and forest stand. The soil lead content was determined by atomic absorption spectrometry. The effect of lead on the occurrence, growth and sporulation of the fungi was studied. Lead concentration of up to 160 &mu;g g-1 was recorded from the roadside, habitat soils. This decreased with increase in distance away from the road. The mucoraceous fungi showed a decline in frequency of occurrence and species diversity with increasing lead pollution load in the soil. However, Cunninghamella spp. were predominantly present in the heavily contaminated soils and showed good in vitro growth in lead agar medium. Cunninghamella. elegans, which was the most common species showed tolerance for lead. Theses results showed that lead negatively affected the occurrence and diversity of mucoraceous fungi. The presumed tolerance of lead by species of Cunninghamella presents them as candidates for use in remediation of contaminated soils. Key Words: Mucorales, soil fungi, soil contamination, lead, pollution, exhaust fumes. J. Trop. Microbiol Vol.2 2003: 27-34

Impacts of traffic-induced lead emissions on air, soil and blood lead levels in Beirut.

Lead is a purely toxic heavy metal which induces a wide variety of adverse physiologic effects. Nevertheless, it has been mined and used for more than 8,000 years. Among the different contemporary sources of lead pollution, traffic-induced emissions from the combustion of leaded gasoline is of particular concern, as it can constitute more than 90 percent of total lead emissions into the atmosphere in congested urban areas where no phase-out activities have been adopted. Gasoline lead content and traffic volume are strongly correlated with concentrations of lead in various environmental media. In the absence of policies to reduce the use of lead in gasoline or to favor the use of unleaded gasoline, leaded gasoline remains the predominant grade in many countries. This paper assesses the status of lead pollution from the combustion of leaded gasoline in Beirut based on field measurements of lead in air and roadside dust of urban and rural/suburban areas and recent data on soil and blood lead levels. Average atmospheric lead concentrations was about 1.86 microg m(-3) at urban locations and 0.147 microg m(-3) at suburban locations. The analysis of roadside dust revealed an average lead level of 353 microg g(-1) along urban streets and 125 microg g(-1) along rural/suburban roads. Blood lead levels were also relatively high in comparison to countries where leaded gasoline has been phased-out.

Lead poisoning of seabirds: environmental risks from leaded paint at a decommissioned military base.

The sources and risk factors for lead exposure to humans are relatively well recognized, yet much less is known about lead exposure risks and effects to wildlife. Here we utilized lead isotopic fingerprinting to investigate sources of elevated lead exposure to Laysan albatross (Phoebastria immutabilis) chicks in the Midway Island National Wildlife Refuge, which was established on the site of a decommissioned military base that previously had undergone lead remediation. Whole blood from chicks as well as soil and paint chips from the chicks' nests were collected from birds nesting close to (<5 m, building site) and distant from (>100 m, reference site) buildings and analyzed for lead levels and isotopic compositions using magnetic sector ICP-MS. Blood lead levels of chicks from the building site had a geometric mean of 190 microg/dL (average = 320 +/- 310 SD, range = 6.8-1400, n = 21) as compared to 4.5 microg/dL (average = 6.0 +/- 4.2 SD, range = 1.2-13, n = 15) in chicks from the reference site. Nest soil lead levels from both sites were similar and relatively low (0.05-11 microg/g) unless visibly contaminated with paint chips (building site). Isotopic analyses confirmed that leaded paint was the source of lead poisoning in these chicks and showed that the pathway of exposure was via direct ingestion of paint chips and not through contaminated soil. This study found continued risk to wildlife and possibly humans from lead hazards in a wildlife refuge established on a decommissioned military base. In addition, this study demonstrates the utility of lead isotopes to identify environmental lead hazards and exposure pathways to wildlife.

Hierarchical sampling of multiple strata: an innovative technique in exposure characterization

Sampling of multiple strata, or hierarchical sampling of various exposure sources and activity areas, has been tested and is suggested as a method to sample (or to locate) areas with a high prevalence of elevated blood lead in children. Hierarchical sampling was devised to supplement traditional soil lead sampling of a single stratum, either residential or fixed point source, using a multistep strategy. Blood lead (n=1141) and soil lead (n=378) data collected under the USEPA/UCI Tijuana Lead Project (1996–1999) were analyzed to evaluate the usefulness of sampling soil lead from background sites, schools and parks, point sources, and residences. Results revealed that industrial emissions have been a contributing factor to soil lead contamination in Tijuana. At the regional level, point source soil lead was associated with mean blood lead levels and concurrent high background, and point source soil lead levels were predictive of a high percentage of subjects with blood lead equal to or greater than 10μg/dL (pe 10). Significant relationships were observed between mean blood lead level and fixed point source soil lead (r=0.93; P<0.05; R2=0.72 using a quadratic model) and between residential soil lead and fixed point source soil lead (r=0.90; P<0.05; R2=0.86 using a cubic model). This study suggests that point sources alone are not sufficient for predicting the relative risk of exposure to lead in the urban environment. These findings will be useful in defining regions for targeted or universal soil lead sampling by site type. Point sources have been observed to be predictive of mean blood lead at the regional level; however, this relationship alone was not sufficient to predict pe 10. It is concluded that when apparently undisturbed sites reveal high soil lead levels in addition to local point sources, dispersion of lead is widespread and will be associated with a high prevalence of elevated blood lead in children. Multiple strata sampling was shown to be useful in differentiating among sources by site-specific association to mean blood lead and the prevalence of elevated blood lead at the regional level.

Water-soluble species and heavy metal contamination of the petroleum refinary area, Jordan.

The levels of lead, cadmium, copper, zinc, aluminum, chromium, and iron in street dust, soil, and plants in the Jordanian petroleum refinery were determined using flame and graphite-furnace atomic absorption spectrophotometry. Major cations (Li+, Na+, NH4+, K+, Mg2+, and Ca2+) and anions (F-, Cl-, NO3-, SO4(2-), and Br-) were also determined using suppression mode ion chromatography. Generally, higher levels of the heavy metals studied were found in street dust samples than in soil samples. On the other hand, except Cl-, and Li+ ions, other anions and cations showed higher concentrations in soil than in street dust samples. For plant samples, unwashed samples showed higher levels of heavy metals than their washed counterparts, indicating that dust fall is a source of heavy metal contamination.

The high cost of improper removal of lead-based paint from housing: a case report.

The costs of lead-based paint hazard control in housing are well documented, but the costs of cleanup after improper, inherently dangerous, methods of removing lead-based paint are not. In this article we report a case of childhood lead poisoning and document the costs of decontamination after uncontained power sanding was used to remove paint down to bare wood from approximately 3,000 ft(2) of exterior siding on a large, well-maintained 75-year-old house in a middle-income neighborhood. After the uncontrolled removal of lead-based paint, interior dust lead levels ranged from 390 to 27,600 micro g Pb/ft(2) (on floors and windowsills) and bare soil lead levels ranged from 360 ppm in the yard to 3,900 ppm along the foundation to 130,000 ppm in the child's play area, well above applicable U.S. Department of Housing and Urban Development/U.S. Environmental Protection Agency standards. The hard costs of decontamination were over $195,000, which greatly exceeds the incremental cost of incorporating lead-safe work practices into repainting. This case report highlights the need to incorporate lead-safe work practices into routine repainting, remodeling, and other renovation and maintenance jobs that may disturb lead-based paint.

Platinum levels in natural and urban soils from Rome and Latium (Italy): significance for pollution by automobile catalytic converter

Platinum concentrations in topsoil samples collected in 1992 (48) and in 2001 (16) from the urban area of Rome have been determined by ICP–MS. Concentrations in 47 soil samples collected in 1992 from natural sites of Latium (an area around Rome) have been determined for a first assessment of natural background levels. The Pt concentrations in Rome urban soils collected in 1992 range from 0.8 to 6.3 ng/g ( X ̄ =3.8±1.0) overlapping the concentration range of natural soils from Latium ( X ̄ =3.1±2.1 ng/g). No significant correlation has generally been found between Pt contents in the ‘natural’ soils and related bedrock or major pedogenetic parameters. These results suggest that there is no evidence of Pt pollution in Rome urban soils at that time, because the massive use of the automobile catalytic converter has only just started. Higher (up to six times more) Pt concentrations, than those measured in the 1992 samples, have been measured, in some cases, in Rome urban soils collected in 2001, suggesting a possible start of Pt accumulation because of the large-scale use in the last decade of automobile catalytic converters. At the same time, a clear decrease of lead levels in Rome urban soils with respect to the levels measured in 1992 has been observed, paralleling the decreasing number of lead gasoline-fuelled cars. Here we present one of the first systematic studies for defining background levels of Pt in Italian natural soils, thus allowing for monitoring, in the future, should any possible Pt pollution caused by the use of automobile catalytic converter, especially in urban soils, occur.

Relationships between Levels of Lead, Cadmium, Zinc, and Copper in Soil and Settleable Particulate Matter in Cartagena (Spain)

In this article we report the relationships between heavy metals (Pb, Cd, Zn, Cu) in soil and settleable particulate matter using data from 6 yr at six different sampling points within Cartagena, a Spanish Mediterranean city. The use of enrichment factors and factor analysis allowed us to predict the major sources of these metals. Soils were classified as one of three types: soils from polluted zone L, soils from polluted zone Z, and non-polluted soils. Settleable particulate matter was also classified in the following three groups: Industrial zone, Urban zone, and Intermediate zone. Enrichment factors showed that soils from polluted zone L are enriched in Pb and Cd when compared with soils from polluted zone Z, and soils from polluted zone Z are enriched in Zn and Cu when compared with soils from polluted zone L. In this context, soils from polluted zones L and Z are identified as specific sources of metals in the settleable particulate matter samples. We also suggest the importance of anthopogenic contribution of metals to soil-enrichment from ancient times up to the present. This process was most severe during the XIX century, when our city suffered an important industrial development. The concentration of these heavy metals are also affected by regional meteorological conditions, which include scarce rainfalls and a significant wind dispersion of soil aerosols.

Lead, Copper and Zinc Levels in Soils along Kaduna-Zaria Highway, Nigeria

Soil samples collected along the left (l) and right (r) sides of a heavy traffic Kaduna-Zaria highway were analysed for lead, copper and zinc using energy dispersive X-ray spectrometry. Levels of lead, copper and zinc from sampled soils were found to be higher than the control samples collected 2 meters away from the highway. The mean concentration ranges of Pb (l), Pb (r), Cu (l), Cu (r), Zn (l) and Zn (r) in the samples are 23-121, 21-99, 40-156, 39-262, 30-118 and 30-162 ppm respectively. Statistical analysis showed positive correlation between the el ements analysed, however correlation is only partially significant between lead and zinc. Lead and zinc levels may be attributed to pollution emanating from automobile emission and contamination while copper level could be due to pollution from fungicides and insecticides. KEYWORDS: Copper, lead, zinc, Energy Dispersive X-Ray Spectrometry, soil pollution. [Global Jnl Environ Sci Vol.1(1) 2002: 7-14]

Elevated dentine-lead levels in deciduous teeth collected from remote first nation communities located in the western James Bay region of northern Ontario, Canada.

Teeth were collected from First Nation schoolchildren inhabiting the remote western James Bay region of northern Ontario, Canada. Lead levels in dentine chips were determined by graphite furnace atomic absorption spectrometry, for naturally exfoliated deciduous teeth. Within exfoliated teeth (one tooth supplied per person), no significant differences in lead concentrations between tooth type were found (P = 0.36). The mean lead concentration of exfoliated teeth of 9.2 microg g(-1) dry weight (N = 61) from this remote region was comparable to levels reported by others for children inhabiting urban centers or residing near smelters. Further, 24.6% (N = 15) had elevated dentine-lead levels ( > 10 microg g(-1)). Lead levels in soil, water, and air have been reported as being low and unimportant sources of exposure for people of the western James Bay area. Evidence is reviewed suggesting that lead contaminated game meat was one source of environmental lead exposure. Consumption data indicate that wildlife is still an important food source for First Nation people of the western James Bay region; 98% (46/47) of the children surveyed consumed some type of wild meat.

An Analysis of the EPA's Proposed Lead Hazard Standards For Homes

Exposure to lead in homes poses such large risks to children's health that reducing it is a major public health priority. To limit these risks, the Environmental Protection Agency (EPA) recently proposed national standards to identify hazardous levels of lead dust and lead in soil, as well as hazardous conditions for lead-based paint. Meeting those standards would require controls that would cost an average of thousands of dollars per home in 21 million homes where lead-based paint is present, according to the EPA. Although the EPA believes its proposed standards reflect an appropriate balancing of benefits and costs, a proper assessment of its proposal suggests otherwise. Each of the EPA's proposed standards for paint, soil and dust would result in measures to control lead that have costs in excess of benefits. Together those costs, less the associated benefits, are likely to exceed $20 billion. Estimates of net costs would be still greater if based on an analysis that corrects remaining deficiencies in the EPA's work. The EPA's proposal would likely increase unnecessarily the premature abandonment of housing in instances where control costs are large relative to the market value of homes. Such abandonment is especially undesirable because it will occur mostly in low-income neighborhoods of older homes. Standards with lower costs would result in less abandonment. The EPA's media-specific, national standards would have other undesirable consequences. Perversely, about half of all the homes that do not meet the standards have risks of elevated blood-lead less than at other homes in full compliance with the standards. In addition, all homes built before 1978 would be subject to the same national standards, although exposure, risk and the cost of controls vary substantially among different households. As a consequence, the EPA's standards would result in controls in homes of more than one million middle-income families whose children face risks lower than the risks for children of poor families living in homes that meet the standards. Controls to reduce low risks are not likely to be cost-effective and are unfair to families facing lower risks who would bear the brunt of the control costs. The EPA can set standards that would offer greater net benefits and avoid controls in lower-risk homes. To provide greater net benefits, the EPA should set less stringent standards based on a more careful reappraisal of the benefits and costs of controlling residential lead hazards. To avoid control measures in lower-risk homes, the EPA should set standards based on lead levels in all media and establish a range of lead levels where recommendations to control lead depend on risk factors specific to individual homes