Benchmark dose approach for low-level lead induced haematogenesis inhibition and associations of childhood intelligences with ALAD activity and ALA levels

Lead (Pb) levels, delta-aminolevulinic acid dehydratase (ALAD) activities, zinc protoporphyrin (ZPP) levels in blood, and urinary delta-aminolevulinic acid (ALA) and coproporphyrin (CP) concentrations were measured for 318 environmental Pb exposed children recruited from an area of southeast China. The mean of blood lead (PbB) levels was 75.0 μg/L among all subjects. Benchmark dose (BMD) method was conducted to present a lower PbB BMD (lower bound of BMD) of 32.4 μg/L (22.7) based on ALAD activity than those based on the other three haematological indices, corresponding to a benchmark response of 1%. Childhood intelligence degrees were not associated significantly with ALAD activities or ALA levels. It was concluded that blood ALAD activity is a sensitive indicator of early haematological damage due to low-level Pb exposures for children.     

Effect of the delta-aminolevulinic acid dehydratase gene polymorphism on renal and neurobehavioral function in workers exposed to lead in China

Effects of delta-aminolevulinic acid dehydratase (ALAD) polymorphisms on the renal and neurobehavioral functions were investigated in Chinese workers from a storage battery plant exposed to inorganic lead. Blood and urine were collected from each worker to determine the ALAD genotypes, blood lead levels (PbB), urinary β2-MG and urinary NAG activity. The World Health Organization Neurobehavioral Core Test Battery (WHO-NCTB) was used. Of the 135 lead workers tested for ALAD genotype, 126 were ALAD1-1, 9 were ALAD1-2 but none were ALAD2-2. The gene frequencies of ALADl-1 and ALADl-2 were 93.33% and 6.67%, respectively. The workers with ALAD1-2 genotype had significantly higher concentrations of PbB (62.52 µg/dl vs. 41.02 µg/dl), urinary NAG (22.01 U/gCr vs. 13.49 U/gCr), urinary β2-MG (194.98 μg/gCr vs. 112.88 μg/gCr), and digit span backward (DSB) score (6.67 vs. 5.33) than those of ALAD1-1 genotype. Urinary NAG of ALAD1-2 genotype carriers was significantly higher than that of ALAD1-1 genotype under the same blood lead level (b_i 0.75 vs. b_i 0.29). Interaction between PbB and ALAD genotypes has a significant influence on NAG (P = 0.02) and β₂-MG (P = 0.01). It is postulated that the workers with the ALAD2 allele appear to be more susceptible to the effects of lead on renal injury, whereas neurobehavioral functions in ALAD1 homozygote tend to be more vulnerable.     

Market survey on toxic metals contained in tattoo inks

Tattooing practice is adopted worldwide and represents an important socio-cultural phenomenon, but, the injection into the skin of coloring agents as metals might pose a risk for allergies and other skin inflammations as well as for systemic diseases. In this context, 56 inks for tattooing purchased from 4 different supply companies were analyzed for metal concentration. Aliquots of pigments were microwave digested by nitric acid, fluoridric acid and hydrogen-peroxide and Al, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sr and V were quantified by sector field inductively coupled plasma mass spectrometry. Limits of quantification varied from 0.07 ng/ml (Cd) to 10 ng/ml (Al and Fe); recoveries ranged from 92% (Cd and Sb) to 109% (Sr); within- and between-day precisions were 3.2% and 4.67% on average.The relative contribution of metals to the tattoo inks composition was highly variable between brands and colors, even in pigments with the same base color. Elements found as the main components of inks were as follows (in µg/g): Al, 1.59–5893; Ba, 0.058–1226; Cu, 0.076–31,310; Fe, 0.717–88,443; Sr, 0.174–36.4. Toxic metals as Cd, Mn, Pb, Sb and V were over the 1 µg/g in a few cases, while Hg was in traces. Among the allergenic metals, Cr was the highest (0.315–147 μg/g), followed by Ni (0.037–9.59 μg/g) and Co (0.0028–6.43 μg/g) then. On 56 tattoo inks, Cr, Ni and Co exceeded the safe allergological limit of 1 µg/g in 62.5%, 16.1% and 1.8% of cases, respectively.     

Milk trace elements in lactating cows environmentally exposed to higher level of lead and cadmium around different industrial units

The present investigation was carried out to assess the trace mineral profile of milk from lactating cows reared around different industrial units and to examine the effect of blood and milk concentration of lead and cadmium on copper, cobalt, zinc and iron levels in milk. Respective blood and milk samples were collected from a total of 201 apparently healthy lactating cows above 3 years of age including 52 cows reared in areas supposed to be free from pollution. The highest milk lead (0.85 ± 0.11 µg/ml) and cadmium (0.23 ± 0.02 µg/ml) levels were recorded in lactating cows reared around lead–zinc smelter and steel manufacturing plant, respectively. Significantly (P < 0.05) higher concentration of milk copper, cobalt, zinc and iron compared to control animals was recorded in cows around closed lead cum operational zinc smelter. Analysis of correlation between lead and other trace elements in milk from lactating cows with the blood lead level > 0.20 µg/ml (n = 79) revealed a significant negative correlations between milk iron and milk lead (r = − 0.273, P = 0.015). However, such trend was not recorded with blood lead level < 0.20 µg/ml (n = 122). The milk cobalt concentration was significantly correlated (r = 0.365, P < 0.001) with cadmium level in milk and the highest milk cadmium (> 0.10 to 0.39 µg/ml) group had significantly (P < 0.05) increased milk cobalt. It is concluded that increased blood and milk lead or cadmium level as a result of natural exposure of lactating cows to these environmental toxicants significantly influences trace minerals composition of milk and such alterations affect the milk quality and nutritional values.     

Distribution and transport of sediment-bound metal contaminants in the rio grande de tarcoles, costa rica (Central America)

A reconnaissance survey of the extent of metal contamination in the Rio Grande de Tarcoles river system of Costa Rica indicated high levels of chromium (Cr) in the fine-grain bed sediments (<60 μm) of tributaries downstream from leather tanneries (50–83 times Cr background or 3000–5000 μg/g). In the main channel of the river downstream of the San Jose urban area, Cr contamination in sediments was 4–6 times background and remained relatively constant over 50 km to the mouth of the river. Sediments from a mangrove swamp at the river mouth had Cr levels 2–3 times above background. Similar patterns of dilution were observed for lead (Pb) and zinc (Zn) sediment contamination, although the contamination levels were lower. The high affinity of Cr towards particulate phases, probably as Cr(III), allows the use of Cr contamination levels for delineating regions of deposition of fine-grained sediments and dilution of particle associated contaminants during transport and deposition.     

Blood lead levels of children and its trend in China

To evaluate Chinese children's blood lead levels (BLLs) and identify its distribution features, we collected articles on children's BLLs published from Jan, 2004 to Aug, 2007 with sampling time since 2001, by searching Chinese Biomedical Disk (CBMDisk), Chinese Journal Full-test Database (CJFD) and other ways. After a rigorous investigation, 35 articles eligible for inclusion criteria were reviewed. Meanwhile, to reveal the trend of Chinese children's BLLs, the data was compared with the results from our former study carried out in 2004, which reviewed the articles published since 1995 to 2003. The results showed that the mean BLLs of Chinese children from 2001 to 2007 was 80.7 μg/L (45.5-165.3 μg/L), and 23.9% (3.2%-80.7%) of children's BLLs was higher than 100 μg/L. Both BLLs and prevalence of BLLs higher than 100 μg/L were lower than that of 1995 to 2003. Of 24 provinces or cities, only 4 showed higher BLLs and higher prevalence rates of lead poisoning (BLLs ≥ 100 μg/L) than that of 1995 to 2003. The mean BLLs of children living in industrial areas were higher than those in urban and suburban areas, and suburban higher than urban areas. Boys' BLLs were 79.3 μg/L, significantly higher than girls 76.9 μg/L (P < 0.001). The results also showed that children's BLLs increased with their ages, and the decreased BLLs for all age were observed comparing with the results of our former study in 2004. Overall, our study revealed that the BLLs of children in China showed a decreasing trend after gasoline with lead was banned in China in 1st July 2000. Our study also showed that the BLLs of children in China were still higher than that in developed countries, which suggested that children's lead poisoning prevention and controlling would be a long-term mission in China.     

Acute and chronic toxicity of lead to rainbow trout salmo gairdneri, in hard and soft water

Lead was found to be highly toxic to rainbow trout in both hard water (hardness 353 mg l⁻¹ as CaCO₃) and soft water (hardness 28 mg l⁻¹. Analytical results differ greatly with methods of analysis when measuring concentrations of lead in the two types of water. This is exemplified in LC50's and maximum acceptable toxicant concentrations (MATC's) obtained when reported as dissolved lead vs total lead added in hard water. Two static bioassays in hard water gave 96-h LC50's of 1.32 and 1.47 mg l⁻¹ dissolved lead vs total lead LC50's of 542 and 471 mg l⁻¹, respectively. In a flow-through bioassay in soft water a 96-h LC50 of 1.17 mg l⁻¹, expressed as either dissolved or total lead, was obtained. From chronic bioassays, MATC's of lead for rainbow trout in hard water were between 18.2 and 31.7 μg l⁻¹ dissolved lead vs 120–360 μg l⁻¹ total lead. In soft water, where exposure to lead was initiated at the eyed egg stage of development, the MATC was between 4.1 and 7.6 μg l⁻¹. With exposure to lead beginning after hatching and swim-up of fry, the MATC was between 7.2 and 14.6 μg l⁻¹. Therefore, fish were more sensitive to the effects of lead when exposed as eggs.     

Health benefits of improving air quality in the rapidly aging Korean society

Korea is experiencing an extraordinarily rapid demographic transition. We investigated the short-term association between air pollution and mortality and assessed the impact of improved air quality on mortality in a rapidly aging city, Seoul, Korea.The generalized additive model (GAM) was used to estimate the relative risks (RR) of mortality associated with changes in air pollution. The time trends, seasonal variations, day of the week effects, and weather effects were controlled in the models. To estimate the health benefits, we used the US Environmental Protection Agency's BenMAP.For people 0–64 years of age, elderly people (65+ years), and all age groups, an increase of 10 μg/m³ in PM₁₀ was associated with increases in daily death counts of 0.27% (95% CI: 0.04–0.50), 0.45% (95% CI: 0.27–0.64), and 0.37% (95% CI: 0.23–0.52), respectively. For ages 0–64 years, elderly people, and all age groups, a 10 ppb increase in 1-hour maximum ozone concentration resulted in an increased risk of daily death counts of 0.28% (95% CI: − 0.19–0.74), 0.96% (95% CI: 0.46–1.47), and 0.81% (95% CI: 0.35–1.26), respectively.For elderly people, it was estimated that the health benefits of attaining the World Health Organization's (WHO) air quality guidelines (AQGs) for PM₁₀ (24-hour average 50 μg/m³) would suggest an annual reduction of 964 (95% CI: 564–1366) premature deaths, and 329 (95% CI: 159–500) premature deaths could be prevented annually in 2015 from attaining the WHO's guidelines for ozone (8-hour average 100 μg/m³).The rapid increase of the elderly population has major consequences and implications for society and public health. This study showed that elderly people are at higher risk for the acute mortality effects of air pollution. Therefore, cleaner air will substantially contribute to improved public health in Seoul, given the growing concern about the adverse effects of air pollution for elderly people.     

Preparation and evaluation of iron–chitosan composites for removal of As(III) and As(V) from arsenic contaminated real life groundwater

A study on the removal of arsenic from real life groundwater using iron–chitosan composites is presented. Removal of arsenic(III) and arsenic(V) was studied through adsorption at pH 7.0 under equilibrium and dynamic conditions. The equilibrium data were fitted to Langmuir adsorption models and the various model parameters were evaluated. The monolayer adsorption capacity from the Langmuir model for iron chitosan flakes (ICF) (22.47 ± 0.56 mg/g for As(V) and 16.15 ± 0.32 mg/g for As(III)) was found to be considerably higher than that obtained for iron chitosan granules (ICB) (2.24 ± 0.04 mg/g for As(V); 2.32 ± 0.05 mg/g for As(III)). Anions including sulfate, phosphate and silicate at the levels present in groundwater did not cause serious interference in the adsorption behavior of arsenate/arsenite. The column regeneration studies were carried out for two sorption–desorption cycles for both As(III) and As(V) using ICF and ICB as sorbents. One hundred and forty-seven bed volumes of As(III) and 112 bed volumes of As(V) spiked groundwater were treated in column experiments using ICB, reducing arsenic concentration from 500 to <10 μg/l. The eluent used for the regeneration of the spent sorbent was 0.1 M NaOH. The adsorbent was also successfully applied for the removal of total inorganic arsenic down to <10 μg/l from real life arsenic contaminated groundwater samples.     

Effects of manganese, copper and lead on Selenastrum capricornutum and Chlorella stigmatophora

Algal assays were conducted to observe the responses of Selenastrum capricornutum and Chlorella stigmatophora to the metals manganese, copper and lead, added singly or in combination to both artificial media and natural waters. A 50% reduction in the total algal cell volume of Selenastrum in standard algal assay medium (SAAM) occurred by the addition of either 3.1 mg manganese 1⁻¹ 85 μg copper 1⁻², or 140 μg lead 1⁻¹. For Chlorella grown in 28 ppt artificial seawater plus full SAAM nutrients, the corresponding numbers were 50mg manganese 1⁻¹, 70 μg copper 1⁻¹ or 700 μg lead 1⁻¹. Of the metals tested, only lead was found in higher concentrations in urban and agricultural runoff than at least one of these levels.Theoretical considerations show that a product model is a more reasonable reference for no-interaction than an additive model for experiments in which toxic metals are added in combination. Combination experiments, in which any combination of the three metals act at the same time, indicate (1) synergism between manganese and copper, (2) antagonism between manganese and lead, and (3) antagonism between copper and lead. As to the manganese-lead interaction, it is shown that the lead-induced inhibition of cell division is offset, partially for Selenastrum and completely for Chlorella by the addition of manganese.     

Evaluation of lead exposure in workers at secondary lead smelters in South Korea: with focus on activity of erythrocyte pyrimidine 5'-nucleotidase (P5N)

To evaluate lead exposure among secondary lead-smelting workers with a focus on erythrocyte pyrimidine 5'-nucleotidase (P5N) activity, blood lead concentration (PbB), activity of P5N and other biological variables were examined in 88 exposed workers in five secondary lead smelters and in 24 non-exposed workers in Korea. All of the mean values of air lead concentration (PbA) in the three processes, scrap pretreatment, blast furnace smelting, and refining and casting of the secondary lead smelters, markedly exceeded 0.05 mg/m3. In this survey, 29 (97%) of 30 air samples for lead exceeded 0.05 mg/m3. The highest mean PbA and PbB values were found in the section of blast furnace smelting. All of the mean PbB values in all the sections were higher than 30 microg/dl. PbB of 71 (81%) of the 88 exposed workers exceeded 30 microg/dl. In 31 (35%) of the exposed workers, PbB was above 60 microg/dl. Compared with the non-exposed group, zinc protoporphyrin (ZPP) in the exposed group was significantly increased, whereas erythrocyte P5N activity and activity of erythrocyte delta-aminolevulinic acid dehydratase (ALAD) were significantly inhibited. Erythrocyte P5N activity had valid biological correlation with PbB and with other biological variables, such as ALAD activity or ZPP. Lead exposure affected hemoglobin levels via inhibition of P5N activity, as well as the heme biosynthetic pathway, in the high-exposure state.     

Chronic toxicity of water-borne and dietary lead to rainbow trout (Salmo Gairdneri) in lake Ontario water

Rainbow trout (Salmo gairdneri) exposed to lead in Lake Ontario water demonstrated a 21-day LC₅₀ of 2.4 mg l⁻¹ lead. At lead concentrations ranging from 3 to 120 μg l⁻¹, log₁₀ of lead concentrations in most tissues of exposed fish appeared linearily related to log₁₀ of lead concentrations in water. Highest concentrations occurred in opercular bone followed by gill and kidney. Lead accumulation by brain was not clearly demonstrated. Exposure to lead in water at concentrations as low as 13 μg l⁻¹ caused significant increases in red blood cell (RBC) numbers, decreases in RBC volumes, decreases in RBC cellular iron content and decreases in RBC δ-amino levulinic acid dehydratase activity. No changes were observed in hematocrit or whole blood iron content. The changes indicated increased erythropoiesis to compensate for inhibition of hemoglobin production and increased mortality of mature red blood cells. After 32 weeks exposure to 120 μg l⁻¹ lead in water, 30% of remaining fish exhibited black tails, an early indication of spinal deformities. Lead added to food was not available for lead uptake by fish. Lead content of fish exposed to dietary lead was not elevated above control levels and the majority of lead consumed could be accounted for in the faeces. Dietary lead may have slightly inhibited uptake of dietary iron.     

Characterization of winter airborne particles at Emperor Qin's Terra-cotta Museum, China

Daytime and nighttime total suspended particulate matters (TSP) were collected inside and outside Emperor Qin's Terra-cotta Museum, the most popular on-site museum in China, in winter 2008. The purpose of this study was to investigate the contribution of visitors to indoor airborne particles in two display halls with different architectural and ventilating conditions, including Exhibition Hall and Pit No.1. Morphological and elemental analyses of 7-day individual particle samples were performed with scanning electron microscopy and energy dispersive X-ray spectrometer (SEM-EDX). Particle mass concentrations in Exhibition Hall and Pit No.1 were in a range of 54.7–291.7 μg m^− 3 and 95.3–285.4 μg m^− 3 with maximum diameters of 17.5 μm and 26.0 μm, respectively. In most sampling days, daytime/nighttime particle mass ratios in Exhibition Hall (1.30–3.12) were higher than those in Pit No.1 (0.96–2.59), indicating more contribution of the tourist flow in Exhibition Hall than in Pit No. 1. The maximum of particle size distributions were in a range of 0.5–1.0 μm, with the highest abundance (43.4%) occurred in Exhibition Hall at night. The majority of airborne particles at the Museum was composed of soil dust, S-containing particles, and low-Z particles like soot aggregate and biogenic particles. Both size distributions and particle types were found to be associated with visitor numbers in Exhibition Hall and with natural ventilation in Pit No.1. No significant influence of visitors on indoor temperature and relative humidity (RH) was found in either display halls. Those baseline data on the nature of the airborne particles inside the Museum can be incorporated into the maintenance criteria, display management, and ventilation strategy by conservators of the museum.     

Environmental lead exposure of an urban Indian population

Environmental lead exposure of the Greater Bombay population has been estimated by measuring lead concentrations in air particulates, water, food and cigarette smoke. Atmospheric lead concentrations in different zones of the city varied between 82 and 605 ng m⁻³. The dietary intake of lead is estimated to be 245 μg day⁻¹ and is calculated from the lead content in different food groups and the amount of that group consumed by an average resident of the city. The uptake by a non-smoker living in the city area is estimated to be 33 μg of lead per day, 75% of which comes from food, 15% from air and 10% from water. For a suburban resident 85% of the lead intake comes from food. The blood lead measurements and the contribution of atmospheric lead to the blood lead level are discussed.     

Evaluation of home lead remediation in an Australian mining community

In 1994 a comprehensive program was established to reduce children's blood lead levels in Broken Hill, NSW, Australia. Home remediation (abatement of lead hazards in a child's home) was included as part of a case management strategy for children with blood lead levels ≥ 15 µg/dL. Children with blood lead levels ≥ 30 µg/dL were offered immediate home remediation. Children with blood lead levels of 15-29 µg/dL were allocated to ‘immediate’ or ‘delayed’ home remediation; a subset of these participated in a randomized controlled trial (RCT) to evaluate the effectiveness of home remediation for reducing blood lead levels. One hundred and seventeen children received home remediation. One hundred and thirteen returned for follow-up blood tests, 88 of whom participated in the RCT. On average children's blood lead levels decreased by 1.7 µg/dL (10%) in the 6 months after remediation and by 2.2 µg/dL (13%) in the 6-12 months after remediation. However, remediation did not significantly change the rate of decline in blood lead levels (P = 0.609). There was no evidence of association between change in children's blood lead levels and changes in lead loading in their homes. The results are consistent with the published literature, which suggests that home remediation does not reduce children's exposure to lead sufficiently to cause a moderate or greater decrease in their blood lead level. In communities where lead is widely dispersed, the study suggests that it is important to assess potential sources and pathways by which children are exposed to lead when developing an intervention plan, and the need for multiple interventions to effectively reduce blood lead levels. The findings reinforce the ongoing need for rigorous epidemiological evaluation of lead management programs to improve the evidence base, and for effective primary prevention to avoid children being exposed to lead in the first place.     

Lead associated caries development in children living in a lead contaminated area, Thailand

In an observational cross-sectional design, a sample of 292 children aged 6-11 years from two primary schools around a shipyard area, known to be an area contaminated with lead (from the industry), were examined to verify the cariogenicity of lead. The number of decayed and filled surfaces on deciduous teeth (dfs), and the number of decayed, missing, and filled surfaces on permanent teeth (DMFS), the salivary flow rate, pH, buffer capacity, oral hygiene, Lactobacillus spp. and mutans streptococci counts were recorded. The mean (range) of DMFS and dfs were respectively 1.3 (range 0-17) and 13.2 (range 0-45); and the geometric mean blood lead level (PbB) and SD were 7.2 and 1.5 microg/dl. The level of dfs, but not DMFS correlated with the blood lead level (R(s)=0.25, p=0.00 / R(s)=0.09, p=0.14). The odds ratio for DMFS>or=1 and dfs>5 for a doubling of PbB after adjusting for other factors were 1.28 (95%CI, 0.81-2.04; p value=0.35) and 2.39 (95%CI, 1.36-4.20; p value=0.004), respectively. The cariogenicity of lead is evident in deciduous teeth but not in permanent teeth for this age group.     

Whole blood, serum, and saliva lead concentrations in 6- to 8-year-old children

With increasing evidence of adverse health effects of lower lead levels (below 10 µg/dL in whole blood), studies on novel internal dose biomarkers are needed. This study aimed at: (1) assessing the lead exposure by measuring this element in whole blood (Pb-blood), serum (Pb-serum), and 3 different types of saliva: whole (Pb-whole-saliva), submandibular/sublingual (Pb-sub-saliva) and parotid saliva (Pb-parotid-saliva); (2) correlating Pb-blood with Pb-serum; and (3) relating Pb-blood and Pb-serum with the lead found in the different salivas. The study population included 444 children aged 6 to 8 years attending 4 government schools in the district of Campos Eliseos, in Ribeirao Preto, Sao Paulo State, Brazil. Whole blood, serum, parotid, submandibular/sublingual (“sub-saliva”), and whole saliva were collected in trace element-free tubes. Lead concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Median Pb-blood and Pb-serum were 2.1 µg/dL and 0.4 µg/L, respectively. Ten percent of the children had Pb-blood between 4.0 and 9.4 µg/dL. Boys showed higher Pb-blood than girls (2.3 vs. 2.0 µg/dL, p < 0.0003). Lead concentrations in whole, sub, and parotid saliva were 1.7, 1.4, and 1.3 µg/L, respectively. No significant correlations were found between Pb-blood and Pb-serum, between Pb-blood and lead in the 3 different salivas, or between Pb-serum and Pb-whole-saliva or Pb-sub-saliva. However, there was a weak statistically significant correlation between Pb-serum and Pb-parotid-saliva. In conclusion, the mean Pb-blood concentration was 2.4 µg/dL, with 10% of the children exhibiting Pb-blood between 4.0 and 9.4 µg/dL. Boys presented higher Pb-blood. Results suggest that Pb-blood has no correlation with Pb-serum or lead in the 3 different salivas collected here. A weak but statistically significant correlation between Pb-serum and Pb-parotid-saliva was found. Our results also point to the need for carrying out more studies on sources of exposure and lead levels in children in Brazil.     

Relationship between "chelatable lead" and the indicator of exposure and effect in current and past occupational exposure

The behaviour of blood (PbB) and two biological indicators of effect: erythrocyte protoporphyrin (EP) and urinary aminolaevulinic acid (ALAU), were studied in subjects who had ceased working with inorganic lead for at least one year. The relationships between these indices and chelatable lead (PbU-EDTA) were also analysed. As a comparison, a group of subjects currently exposed to inorganic lead was studied. At a given PbU-EDTA level, the PbB values were significantly lower in the workers with past exposure than those found in currently exposed subjects. The relationship between EP and PbU-EDTA illustrates that, for corresponding levels of chelatable lead, the values of the erythrocyte metabolite are identical in the two groups. Considering the EP-PbB relationship, however, at a given PbB level the protoporphyrin values appear distinctly more altered in the subjects with past exposure. The relationship between ALAU and PbU-EDTA shows that, at a given PbU-EDTA level the urinary metabolite in past exposed subjects is distinctly lower than in currently exposed workers, while the relationship between ALAU and PbB shows that, at similar blood lead values, the ALAU levels are identical in both groups. On the basis of these results, it is concluded that in subjects with past exposure, erythrocyte protoporphyrin can be used in establishing the persistence and extent of an "active deposit" of lead in the organism, while PbB and ALAU are of very limited value.     

Contributions of risk factors to elevated blood and dentine lead levels in preschool children.

The relationship between blood lead level (PbB) and an array of socio-demographic, behavioral, caregiving and environmental risk factors was investigated in a cohort of socioeconomically disadvantaged urban children at ages 2, 3 and 4 years and 10 months. The risk factors were also related to dentine lead level (PbD) from shed deciduous teeth. Strong persistent pairwise relationships with PbB and PbD were observed for maternal IQ, parental education, examiner ratings of the condition and cleanliness of the physical environment, and the HOME scale, which assesses the quality of the caretaking environment. The association between dirt pica and PbB was strong at 2 years (r = 0.30), but was less pronounced in subsequent assessments as the prevalence of pica decreased. Insignificant or weak relationships were found for maternal assessments of paint-and-plaster peeling in the home and non-dirt pica. The HOME scale and the ratings of the condition of the physical environment were significantly related to PbB and PbD even after adjustment for socio-demographic factors. These two measures were also strongly related to an array of developmental outcomes. The results indicate that statistical adjustment specifically for the quality of the caretaking environment can lead to substantial reductions in estimates of adverse lead effects.     

Cadmium and lead in selected tissues of two commercially important fish species from the Adriatic Sea

Baseline levels of cadmium and lead were determined in muscle tissue and liver of hake (Merluccius merluccius) and red mullet (Mullus barbatus), two commercially important fish species from the eastern Adriatic. Concentrations of trace metals in liver (Cd: 6–183 μg kg⁻¹ w. wt. ; Pb: 39–970 μg kg⁻¹ w. wt.) were within the range of recently published data for the Mediterranean. In the muscle tissue, cadmium concentrations (4.1–29 μg kg⁻¹ w. wt.) were among the lowest reported values for the Mediterranean, whereas lead levels (49–158 μg kg⁻¹ w. wt.) were within the range of values reported for various coastal areas of the Mediterranean. Presented data on cadmium and lead content in the studied fish species provide no proof of the general pollution of the Adriatic. Obtained data were tested in relation to fish length. Metal concentrations in liver decreased with the increase in fish size, whereas no significant correlation was found between trace metal levels in the muscle tissue and the length of both species. Relationships between metal concentrations and sex were also tested, but they gave no significant results. A comparison of contaminant concentrations in the edible tissue of hake and red mullet with the Croatian legislation shows that the consumption of their meat is not harmful for humans, not even for the most endangered population from the coastal region.