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PubMed1991

Lead exposure from conventional and cottage lead smelting in Jamaica.

A survey was conducted to determine the distribution and determinants of environmental and blood lead levels near a conventional and several cottage lead smelters and to assess the relationship between environmental and blood lead levels in a tropical, developing-country setting. Fifty-eight households were studied in the Red Pond community, the site of the established smelter and several backyard smelters, and 21 households were studied in the adjacent, upwind Ebony Vale community in Saint Catherine Parish, Jamaica. Households were investigated, using questionnaires, soil and housedust lead measurements, and blood lead (PbB) measurements from 372 residents. Soil lead levels in Red Pond exceeded 500 parts per million (ppm) at 24% of households (maximum--18,600 ppm), compared to 0% in Ebony Vale (maximum 150 ppm). Geometric mean PbB in Red Pond, where 44% of children less than 6 years of age had PbB levels greater than or equal to 25 micrograms per deciliter (micrograms/dL), was more than twice that Ebony Vale in all age groups (p less than 0.0005). Within Red Pond, proximity to backyard smelters and to the conventional smelter were independent predictors of soil lead (p less than 0.05). Soil lead was the strongest predictor of PbB among Red Pond subjects under 12 years of age. The blood lead--soil lead relationship in children differed from that reported in developed countries; blood lead levels were higher than expected for the household-specific soil lead levels that were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1983

The metabolism of lead in isolated bone cell populations: interactions between lead and calcium.

Previous studies of lead metabolism in bone organ culture have defined, in part, an exchangeable bone lead compartment regulated by the same ions and hormones that normally control bone cell metabolism. This study was undertaken to further characterize this subcompartment of exchangeable lead and to examine possible interactions between lead and calcium in isolated bone cell populations. Bone cells, derived from mouse calvaria, were enriched for osteoclasts (OC) and osteoblasts (OB) by a sequential collagenase digestion. We found that (1) the uptake of 210Pb by OC cells was rapid, and OC cells had greater avidity for lead, compared to OB cells, at concurrent time points of incubation, (2) OB cells showed very little increase in lead uptake as medium lead concentrations were increased from 6.5 to 65 microM, in contrast, the uptake of lead by OC cells was almost linear, (3) after loading OC cells with 210Pb, significant release of label (approximately 15 to 30%) occurred within short time periods (less than or equal to 2 hr) during incubations in chase medium, (4) parathyroid hormone (PTH) at physiological concentrations effected a marked increase in 210Pb and 45Ca uptake in OC cells, after 5 min of incubation, Pb accumulation into OC cells continued as calcium uptake markedly decreased, (5) this PTH effect on 210Pb uptake was linear over PTH concentrations of 50 to 250 ng/ml, and (6) rising medium concentrations of lead (greater than or equal to 26 microM) markedly enhanced/exaggerated calcium uptake by OC cells, far above that produced by physiological concentrations of PTH. These data indicate that (1) quantitatively, OC cells are the predominant cell type in the metabolism of lead in this in vitro system of OC and OB cell monolayers, (2) mediated incorporation of lead into OC cells occurs and likely involves changes in membrane permeability effected by hormonal stimuli, such as PTH, and (3) modulations in cellular calcium metabolism induced by lead at low concentration may have the potential of disturbing multiple cell functions of different tissues that depend upon calcium as a second messenger.

Animals↗
PubMed1993

Leaded windows as a source of lead within homes.

Corrosion of 'cames', i.e., the lead binding or decorative strips in leaded windows, is a significant, but previously unreported source of lead within older homes. Surfaces close to the leaded windows are highly contaminated with lead but the content of lead in dust diminishes rapidly within the first 2 m away from the window and is minimal after 3 m. The dust near the window was identified, using X-ray diffraction, as mainly composed of basic lead carbonate. Condensation water on leaded windows contains appreciable lead whereas for unleaded windows it is negligible. The exterior surface of unleaded windows contains more lead than the interior surface but the converse is true for leaded windows. A laboratory simulation suggested that corrosion by window condensate was likely to be the principal mechanism by which lead entered the home environment.

Dust↗
PubMed1987

Lead-induced inclusion bodies in rat kidney after perinatal treatment with lead and disulfiram.

The presence of inclusion bodies in renal proximal tubules was studied in rats exposed to lead and/or disulfiram (tetraethylthiuram disulfide). Pregnant rats were treated with only lead acetate (0.25% Pb in the drinking water), only disulfiram (0.1 mmol/kg p.o. twice a week) or with both lead acetate and disulfiram from day 1 of pregnancy and until the offspring were 4 weeks of age. After parturition the disulfiram was given s.c. directly to the offspring instead of to the dams. Treatment was discontinued at weaning and tissue samples from renal cortex were studied by electron microscopy. In lead-treated dams inclusions were present in nuclei of renal proximal tubule cells in the 3 segments with the highest incidence in the middle segment. Inclusions were also present in the cytoplasm. In the offspring, indirectly exposed to lead via the dams, inclusions were present in all 3 segments. No inclusions were present in control rats or in disulfiram-treated rats. Combined treatment with lead and disulfiram resulted in a marked decrease in the incidence of inclusion bodies both in the dams and in the offspring compared to in rats treated with only lead. Diethyldithiocarbamate, a major metabolite of disulfiram, forms a lipophilic complex with lead, and is known to cause pronounced effects on the tissue distribution of lead. The present investigation shows that lead inclusion bodies are formed in the offspring indirectly exposed to lead via the dams during gestation and lactation. Concurrent exposure to disulfiram reduces the incidence of inclusion bodies in renal proximal tubules, probably due to formation of a lead-dithiocarbamate complex.

Animals↗
PubMed2004

The influence of milk intake on the lead toxicity to the sensory nervous system in lead workers.

The dietary calcium supplement has been suggested to children and pregnant women for prevention of lead toxicity, because of lead-calcium interaction. Lead workers were supplied free milk in Taiwan; however, part of workers did not drink milk due to lactose intolerance. The goal of this study is to evaluate the effects of milk-intake on the peripheral nervous system in workers with long-term lead exposure. We measured 181 workers' current perception thresholds (CPT) as neurological outcomes. The outcome variables were then correlated to the subject's milk intake, blood lead levels, and index of long-term lead exposure that was calculated by the subject's serial blood lead data in a period of working duration. The potential confounders, including age, gender, body height, smoking and alcohol consumption, were also collected and analyzed in multiple regressions. 23 workers who reported never or rarely drinking milk, which meant that they have suffered from diarrhea or abdomen discomfort after drinking milk since childhood, had higher blood lead parameters but not statistically significant, and higher thresholds in sensory nerve tests, especially, statistically significance on 5 and 250 Hz of hand CPTs, which represent C fiber and A-delta fiber. In multiple regression models with control of potential confounders, significant protective effects of milk intake were found on reducing hand CPTs, but not on foot CPTs. Our study, using measurement of sensory nerve CPTs, revealed that drinking milk (two bottles a day, about 700 g per day) might have an effect to protect lead peripheral neurotoxicity. The detail biochemical mechanisms need further investigations. However, reduction of occupational lead exposure is the essential way to protect lead neuropathy. The authors did not emphasize that offers of milk to workers could be instead of occupational hygiene efforts. Furthermore, lead workers with lactose intolerance might be more susceptible, and need more industrial hygiene interventions.

Adult↗
PubMed2005

Dealing with lead in Broken Hill--trends in blood lead levels in young children 1991-2003.

The objective of the study was to investigate trends in blood lead concentrations in preschool children between 1991 and 2003, as part of the evaluation strategy of a public health lead management program in Broken Hill, Australia. Since 1991, all Broken Hill children aged 1-4 years have been offered at least annual blood lead screening as part of a community-wide lead management program. Recruitment of children was promoted throughout the period using local media and distribution of promotional material from health care centres and preschool, childcare, and educational facilities around the city. Venous blood samples were collected using standard procedures and analyses were subjected to internal and external quality control programs. Because the frequency distribution of blood lead levels are skewed, geometric rather than arithmetic means were used for comparative purposes. Trend analysis was based on age and sex standardised mean blood lead levels. The number of 1- to 4-year-old children screened ranged between 496 and 948 in any one year and response rates varied between 39% and 73%. The age-sex standardised mean blood lead level decreased from 16.3 microg/dL to 7.1 microg/dL between 1991 and 2003. Overall, blood lead levels declined by 56% over 13 years. These reductions were consistently observed irrespective of age or where a child lived in the town. The rate of decline has slowed since 1997. We conclude that substantial progress has been made in dealing with the lead problem in Broken Hill children, although the rate of decline of blood lead levels has slowed. Continued public health action is still needed to bring the proportion of young children with significantly elevated blood lead levels (>15 microg/dL) down from the 2003 figure of 12% to the NHMRC community-based target for lead in young Australians of 5%.

Child, Preschool↗
PubMed2006

A stable lead isotopic investigation of the use of sycamore tree rings as a historical biomonitor of environmental lead contamination.

The validity of the use of sycamore (Acer pseudoplatanus) tree-rings for the reconstruction of atmospheric lead pollution histories was investigated. Tree cores spanning 1892-2003 were collected from several sycamores from the eastern shore of Loch Lomond, Scotland, an area with no local point sources of lead emission. The lead concentration and 206Pb/207Pb profiles of the Loch Lomond region cores were compared with corresponding data for the 210Pb-dated loch sediment, and also with data for moss of known age from a Scottish herbarium collection. Two of the seven sycamore cores showed the same lead concentration trend as the lead flux to the loch, the rest having no similarity to either each other or the loch sediment record. Two further sycamore cores showed some similarity in their temporal 206Pb/207Pb trends to those seen in the sediment and moss records, but only in part of their profiles, whilst the 206Pb/207Pb ratios of the other sycamore cores remained relatively unchanged for the majority of the time covered, or exhibited an opposite trend. The 206Pb/207Pb ratios of the tree cores were also mostly higher than those of the previously established records for any given time period. Tree cores covering 1878-2002 were also collected along transects from Wanlockhead and Tyndrum, two areas of former lead mining and smelting associated with distinct 206Pb/207Pb ratios of 1.170 and 1.144, respectively. The Wanlockhead tree cores exhibited a generally decreasing trend in lead concentration with both time and distance from the lead mine. The characteristic 206Pb/207Pb ratio of 1.170 was observed in samples close to the mine but a decrease in the influence of the mine-derived lead was observed in more distant samples. The tree sampled at Tyndrum showed elevated lead concentrations, which decreased with time, and a fairly constant 206Pb/207Pb ratio of 1.15 reflecting input from the mine, features not observed in any other trees along the transect. Overall the data suggest that sycamore tree-ring analysis is an unsuitable method for obtaining records of historical lead deposition in areas with no large local lead input, although it can reveal some information about the temporal and spatial influence of point source emitters. The unsuitability probably arises from the number of active annual rings in a single year, the post-uptake radial translocation of elements, the relative importance of the different routes of uptake, and the soil depth(s) from which trees draw nutrients.

Acer↗
PubMed2006

Lead decline in the Indian environment resulting from the petrol-lead phase-out programme.

Recently, the lead content of various environmental components has decreased in response to replacement of leaded petrol by unleaded petrol. In India, 15 research studies are here assessed with respect to lead concentrations in various environmental components during the leaded petrol phase (before 1996), the transitional phase (1996-2000) and the unleaded petrol phase (2000 onwards). The Ganga River Water exhibited a decrease in lead concentration from 18.0 microg/l in 1988 to 3.1 microg/l in 2001. In Lucknow urban centre, mean lead concentrations in the urban air decreased from 1.6 microg/m(3) in 1994 to 0.2 microg/m(3) in 2002. Lead concentrations in Dalbergia sissoo tree leaves also decreased from 18.7 microg/g dry wt. in 1994 to 8.3 microg/g dry wt. in 2004. Mean blood-lead levels of children from Mumbai, Chennai, Bangalore, Amritsar and Lucknow urban centres have fallen from 18.1 microg/dl in the leaded petrol phase to 12.1 microg/dl in the unleaded petrol phase. The petrol-lead phase-out effort in India has reduced lead concentrations in the various environmental components after 2000. It will help to reduce the exposure of millions of people to environmental lead.

Child↗
PubMed2006

Spatial distribution of lead in human primary teeth as a biomarker of pre- and neonatal lead exposure.

Lead remains one of the most hazardous toxins in our environment. Because the toxic effects of lead are most prominent during early development, it is important to develop a suitable biomarker for lead exposure during the pre- and neonatal periods. In the present study, the spatial distribution of lead was measured in the enamel and dentine of ten human primary teeth using laser ablation-inductively coupled plasma-mass spectrometry. The neonatal line, visualized using confocal laser scanning microscopy, was used to demarcate the pre- and postnatal regions of the sample teeth. Lead levels in pre- and postnatally formed enamel and dentine were compared to blood-lead levels measured at birth and one year of age for four of these participants. Mean dentine-lead levels ranged from 0.17+/-0.02 to 5.60+/-1.79 microg/g, and mean enamel-lead levels ranged from 0.04+/-0.01 to 1.47+/-0.20 microg/g. The results of this preliminary study showed that the spatial distribution of lead in dentine reflected the blood-lead levels. The present study demonstrates a methodology where the spatial distribution of lead in the dentine of human primary teeth may be used to obtain temporal information of environmental lead exposure during the pre- and neonatal periods.

Adolescent↗
PubMed1999

Estimation of cumulative lead releases (lead flux) from the maternal skeleton during pregnancy and lactation.

Recent longitudinal studies with human subjects and nonhuman primates using high-precision stable lead isotopes show that lead is mobilized from the maternal skeleton during pregnancy and the postpartum period. We have now calculated the cumulative lead release (lead flux in micrograms) mobilized from the skeleton during these periods by means of analysis of monthly PbB samples from recent immigrants to Australia. Results included a statistically significant inverse relationship (P = .006) between the lead flux and the time of conception after the arrival of the subjects in Australia. By using an area-under-the-curve approach to determine the added lead inputs to blood during pregnancy and nursing versus a baseline value, the net lead release to blood varied from 0.9 to 10.1 microg/d, which is equivalent to 0.3 to 4.03 mg of lead. With group PbB concentrations usually less than 3 microg/dL, the observed releases imply a high skeletal turnover of greater than 10% and possibly greater than 30% in some subjects during pregnancy and the postpartum period. These elevated rates in some subjects may partly arise from low daily calcium intakes, being one half to two thirds of that of recommended daily requirements. The lead flux calculated from a cumulative approach was compared with other approaches: first-order kinetics, bone turnover, bone x-ray fluorescence measurements, and the International Commission for Radiological Protection lead pharmacokinetic model. Calculated lead releases and remaining bone lead concentrations would likely not be detectable by current x-ray fluorescence methods.

Adolescent↗
PubMed2000

Influence of ethanol on lead distribution and biochemical changes in rats exposed to lead.

In the present study, an attempt has been made to investigate the effect of ethanol consumption on the distribution of lead in different regions of brain and body organs of male albino rats. Lead when administered intragastrically, for a period of eight weeks resulted in almost uniform accumulation of this metal in all the regions of brain, which increased by almost two fold when ethanol was given along with lead. Lead was also seen to compartmentalise in almost all the tissues of the body to varying extents, with the highest accumulation in the kidney. A progressive and appreciable accumulation of lead was seen in blood with a concomitant increase in ZPP levels in animals during the course of treatment, which increased further when ethanol was administered along with lead. The activity of delta-ALAD and AChE in blood was significantly decreased in lead as well as ethanol treated animals. However, in animals coexposed to lead and ethanol, the inhibition of delta-ALAD was not significantly different, when compared to only lead-treated animals. The results suggested that animals exposed to ethanol and lead simultaneously accumulate higher levels of lead in blood and brain of animals making them more vulnerable to the haematological and neurological toxic effects of lead.

Acetylcholinesterase↗
PubMed2000

New isotopic evidence for chronic lead contamination in the San Francisco Bay estuary system: implications for the persistence of past industrial lead emissions in the biosphere.

Measurements of lead isotope compositions in unfiltered San Francisco Bay waters from 1989 to 1998 have brought new insights into the cycling of anthropogenic lead in estuaries. Isotopic compositions of lead in the shallow (<2 m) southern reach were essentially invariant ( approximately 90% derived from 1960s-1970s leaded gasoline) during the study period because of limited hydraulic flushing and the remobilization of lead from bottom sediments. In contrast, in the northern reach freshwater flushing from the San Joaquin and Sacramento rivers produced seasonal and decadal variations in lead isotope compositions. The seasonal shifts are attributed to advection of soils containing late 1980s gasoline lead into the bay during winter rains. Mass balance calculations indicate that only a small fraction (1-10%) of this leaded gasoline fallout from the late 1980s has been washed out of the San Joaquin and Sacramento rivers' drainage basin by 1995. Superimposed on this seasonal cycling was a long-term systematic shift in the component of gasoline lead expressed in the river systems, with a small ( approximately 5-10%) decrease in the amount of 1960s-1970s gasoline lead in river and North Bay waters. The retention of gasoline lead in the river systems draining into the bay as well as San Francisco Bay sediments indicates that historic gasoline deposits may remain in the combined riparian/estuarine system for decades. Such a persistence is in contraindication to recent reports of rapid (annual) decreases in lead contamination in other environments, and the link between climate and contaminant transport suggests local or global climate change will have an impact on contaminant distribution and fate.

Industrial Waste↗
PubMed2005

Estimation of burden of lead for offspring of female lead workers: a quality-adjusted life year (QALY) assessment.

This study demonstrates an empirical example that uses quality-adjusted life year (QALY) as a common metric for occupational health assessment to measure the utility loss of potential lead-exposed children delivered by female lead-battery-exposed workers. A set of nationwide health examination data was used for 1726 lead workers. Among them, there were 649 female workers. The numbers of offspring from female lead workers were estimated by multiplying the age-specific fertility rate (ASFR) by the number of workers in each age stratum. The quality of life assessment for these offspring was assumed impaired by increased absorption of lead using a measure of utility for quality of life that was adapted from Rosser's index of health-related quality of life. The total utility loss was calculated by summing up the loss of QALY for these expected offspring. Dose-response and exposure assessments were based on their mothers' blood lead levels. It was estimated that more than 38 babies were delivered in 1 yr. There would be 19 babies born with blood lead levels over 30 microg/dl, and about 17 babies with blood lead between 10 and 29 microg/dl. The expected utility loss of the babies was estimated to be about 216 QALY, of which 51.6 QALY was attributed to the babies with moderate blood lead level, while that of high blood lead was 164.4 QALY. An effective industrial hygiene program to reduce blood lead to 5, 10, and 15 microg/dl in female lead-exposed workers would decrease the utility loss to 169.5, 126.8, and 92.3 QALY, respectively, in the offspring. An alternative policy of raising the age of female workers by 5 or 10 yr before employment would also reduce the loss to 174.6 or 107.4 QALY. Data suggest that an effective industrial hygiene program should be implemented, and the use of QALY as a common metric for comparative assessment of occupational health policy may be feasible.

Adult↗
PubMed1995

Blood lead surveys of communities in proximity to lead-containing mill tailings.

In former mining communities tailings containing up to 2% (20,000 ppm) lead (Pb), frequently as galena (lead sulfide), may be present in large piles near residences, as landfill under homes, or mixed with residential soils. The impact of tailings on blood lead was assessed by comparing blood lead values obtained from residents and environmental lead measured in soils and tailings piles. Data from 13 communities were compiled. Approximately 2995 blood lead measurements were available from persons residing on or near tailings, with the majority of samples from children. Blood lead levels were compared to 1806 controls from nearby communities, national norms, and communities with active smelters. Data comparisons indicated that blood lead values in tailings residents were usually comparable to controls. These data suggest that lead present in mill tailings is not readily bioavailable, even to children who played in dirt or tailings piles. Consequently, the hazard of lead in soils appears to be site-specific and influenced by bioavailability; the bioavailability of galena tailings to humans is low. When health risks of lead soils are predicted, factors affecting the bioavailability of lead present in tailings need to be taken into account.

Biological Availability↗
PubMed2004

Residential dust lead loading immediately after intervention in the HUD lead hazard control grant program.

At the conclusion of most lead hazard control interventions in federally assisted housing built before 1978, a certified clearance examiner must verify that the lead hazard control work was completed as specified and that the area is safe for residents, a process referred to as clearance. This study explores the experience of 14 grantees participating in the Evaluation of the HUD Lead-Based Paint Hazard Control Grant Program in passing clearance. The study also considers how preintervention lead levels (interior dust and paint), building condition/characteristics, and the scope of work influenced initial clearance dust lead loadings and clearance rates. At the initial clearance inspection, 80% of the 2682 dwellings achieved grantee-specific clearance standards on windowsills, window troughs (500 microg/ft2 and 800 microg/ft2, respectively), and floors (80, 100, or 200 microg/ft2 depending on state/local regulations at the dates of clearance in the mid-1990s), with individual grantee success rates ranging from 63 to 100%. Dwellings that failed initial clearance required an average of 1.13 retests to clear. The high level of success at clearance demonstrates that following methods for work site containment, lead hazard control, and cleaning similar to those recommended in the HUD Guidelines for the Evaluation and Control of Lead-Based Paint in Housing is effective. The most common lead hazard control intervention was window abatement accompanied by the repair or abatement of all other deteriorated lead-based paint (56% of dwellings). An additional 5% of dwellings were fully abated, 29% had lower intensity interventions. Interventions including window replacement are recommended to reduce dust lead loading on windowsills and troughs at clearance, but lower level interventions such as full paint stabilization are just as good at reducing floor dust lead loadings. Whatever lead hazard control activities are selected, the condition of the surfaces of interest should be in good condition at clearance.

Air Pollution, Indoor↗
PubMed1998

Relation of nutrition to bone lead and blood lead levels in middle-aged to elderly men. The Normative Aging Study.

The relations of nutritional factors to lead accumulation in the body were examined cross-sectionally among 747 men aged 49-93 years (mean 67 years) in the Normative Aging Study in 1991-1995. Means (standard deviations) for blood lead, tibia lead, and patella lead were 6.2 (4.1) microg/dl, 21.9 (13.3) microg/g, and 32.0 (19.5) microg/g, respectively. In multiple regression models adjusting for age, education level, smoking, and alcohol consumption, men in the lowest quintile of total dietary intake levels of vitamin D (including vitamin supplements) (<179 i.u./day) had mean tibia and patella lead levels 5.6 microg/g and 6.0 microg/g higher than men with intake in the highest quintile (> or =589 i.u./day). Higher calcium intake was associated with lower bone lead levels, but this relation became insignificant when adjustment was made for vitamin D. The authors also observed inverse associations of blood lead levels with total dietary intake of vitamin C and iron. When analyses were controlled for patella lead, age, smoking, and alcohol consumption, men in the lowest vitamin C intake quintile (<109 mg/day) had a mean blood lead level 1.7 microg/dl higher than men in the highest quintile (> or =339 mg/day), while men in the lowest iron intake quintile (<10.9 mg/day) had a mean blood lead level 1.1 microg/dl higher than men in the highest quintile (> or =23.5 mg/day). This study suggests that low dietary intake of vitamin D may increase lead accumulation in bones, while lower dietary intake of vitamin C and iron may increase lead levels in the blood.

Aged↗
PubMed1995

Associations of delta-aminolevulinic acid dehydratase genotype with plant, exposure duration, and blood lead and zinc protoporphyrin levels in Korean lead workers.

Previous studies have suggested that polymorphisms in delta-aminolevulinic acid dehydratase (ALAD), a heme synthetic enzyme, may be associated with differences in blood lead levels, perhaps due to differential binding of lead in erythrocytes. The authors examined associations of ALAD genotype with blood lead and zinc protoporphyrin (ZPP) levels, exposure duration, sex, and plant in 308 currently exposed lead workers in three lead storage battery manufacturing plants in the Republic of Korea in 1993. The overall prevalence of the variant allele, ALAD2, was 11%, but prevalence varied by plant (p = 0.02: 8.6% in plant A, 20% in plant B, and 22% in plant C). While ALAD2 was not associated with mean blood lead levels, the allele was associated with blood lead levels greater than or equal to 40 micrograms/dl (crude odds ratio (OR) = 2.6, 95% confidence interval (CI) 1.1-6.3; adjusted OR = 2.3, 95% CI 0.8-6.2, with adjustment for sex, plant, and exposure duration) and with exposure durations greater than 6 years (adjusted OR = 2.5, 95% CI 1.2-5.4, with adjustment for blood lead, sex, and plant). Among workers in plant C, the highest exposure plant, ALAD2 was associated with lower ZPP levels when controlling for blood lead levels. These data suggest that lead toxicokinetics may be modified by ALAD genotype and that ALAD2 may be protective for the health effects of lead. ALAD genotype also appears to have been a selection factor for current lead exposure status in the studied workers.

Adult↗
PubMed2005

Dietary and inhalation intake of lead and estimation of blood lead levels in adults and children in Kanpur, India.

This research was initiated to study lead levels in various food items in the city of Kanpur, India, to assess the dietary intake of lead and to estimate blood lead (PbB) levels, a biomarker of lead toxicity. For this purpose, sampling of food products, laboratory analysis, and computational exercises were undertaken. Specifically, six food groups (leafy vegetables, nonleafy vegetables, fruits, pulses, cereals, and milk), drinking water, and lead air concentration were considered for estimating lead intake. Results indicated highest lead content in leafy vegetables followed by pulses. Fruits showed low lead content and drinking water lead levels were always within tolerable limits. It was estimated that average daily lead intake through diet was about 114 microg/day for adults and 50 microg/day in children; tolerable limit is 250 microg/day for adults and 90 microg/day for children. The estimated lead intakes were translated into the resultant PbB concentrations for children and adults using a physiologically-based pharmacokinetic (PBPK) model. Monte Carlo simulation of PbB level variations for adults showed that probability of exceeding the tolerable limit of PbB (i.e.,10 microg/dL) was 0.062 for the pre-unleaded and 0.000328 for the post-unleaded gasoline period. The probability of exceeding tolerable limits in PbB level was reduced by a factor of 189 in the post-unleaded scenario. The study also suggested that in spite of the introduction of unleaded gasoline, children continue to be at a high risk (probability of exceeding 10 microg/dL = 0.39) because of a high intake of lead per unit body weight.

Administration, Inhalation↗