Mean Lead Concentration Research Articles

Lead concentrations and isotope ratios in street dust in major cities in Greece in relation to the use of lead in petrol

Until recently, the most important source of environmental lead pollution in cities was thought to come from the combustion of leaded petrol. A simple way to monitor the extent of this phenomenon, used in a number of studies in the past, has been to measure lead levels in street dust. Nowadays, it would be expected that lead concentrations in urban dust would have decreased from earlier values, following the progressive reduction of lead in petrol over the past few years, and this hypothesis has recently been confirmed in Manchester, UK. The object of the present work is to determine levels of lead pollution in cities in Greece on 1997 and, if possible, to discover whether similar reductions in lead concentrations have occurred there also. Surveys have been conducted in Thessaloniki, Athens and Piraeus. Samples of roadside dust were collected from streets (categorised by traffic density), national gardens and school playgrounds, and lead was extracted by digestion with concentrated nitric acid. Lead concentrations were determined by graphite furnace atomic absorption spectrometry and lead isotope ratios measured by inductively coupled plasma mass spectrometry. Results for Thessaloniki showed that mean lead concentrations in all categories of location are similar to present levels in Manchester. Further, lead concentrations in dust in the busiest streets in Thessaloniki have fallen by about 55% since a previous study 17 years ago. In Athens and Piraeus, the lead levels in street dust are much higher and significant differences were observed between the various types of street. In particular, it was observed that lead levels in school playgrounds in these two cities were much higher than in similar locations in Thessaloniki and Manchester, with a possible hazard to children. Isotope ratio measurements showed that Thessaloniki's lead is isotopically distinct from that found in Athens and Piraeus, which presumably reflects differences in sources of supply.

Analysis of Lead Levels in Local Jordanian and Imported Sheep Meat and Organs Using Atomic Absorption Spectrometry

A total of two hundred and forty random samples were collected equally from mutton, liver and kidney of 40 local (Jordanian) and 40 imported Australian sheep (40 each sub sample). Fresh samples were collected from 12-18 m old sheep slaughtered in abattoirs in Jordan in 2002. Besides, 40 fresh mutton samples of imported Chinese sheep were collected from different markets. Atomic absorption spectrometry (AAS) was used to estimate the lead (Pb) content of the samples. Results indicated that Australian mutton had significantly higher (p < 0.05) mean of lead pollution than that of the local and Chinese muttons. The mean concentration of lead (mg/kg) in Australian, local and Chinese muttons was 4.30, 3.15 and 2.17, respectively. The mean concentration of lead in Australian sheep liver was significantly higher (p < 0.05) than that recorded in the local sheep liver. The mean concentration of Pb in Australian and local sheep liver was 5.69 and 4.52 mg/kg, respectively. The mean concentrations of Pb in the kidney of the Australian and local sheep were not significantly different (p > 0.05). They were 4.59 and 3.87 mg/kg, respectively. On the basis of the samples lead level, 85, 92 and 87.5% of local, Australian and Chinese mutton respectively, exceeded the international safe permissible limit of 1.0 mg/kg. Furthermore, the effect of Pb on animal and human health was discussed.

Assessment of the Lead Content in Perna perna Mussels in the Metropolitan Region of the Rio de Janeiro City

Guanabara Bay is the most important estuarine system in Rio de Janeiro City and receives the most untreated effluents of the city. As a consequence of this impact the beaches in the metropolitan zone are heavily polluted. Bivalves mollusks are able to store a wide variety of pollutants from very diluted solutions without visible damage. The Perna perna mussel is a bivalve organism that accumulates metal and thus it is considered an environmental pollution indicator. Native from the region, this species is consumed in the diet by poor people since it is easily available. Lead is one of the most common pollutants in the environment. It is considered toxic to human beings and animals and without any physiological known function in the organism. Lead toxic effects can affect almost all organs and systems of the body. In this work electro-thermal atomic absorption spectrometry was used to determine lead concentration in Perna perna mussels collected at Flamengo, Vermelha and Vidigal beaches located in the metropolitan region of the Rio de Janeiro City. The mean lead concentration found was (2.0 ± 0.93 mg.kg–1) almost 10 times greater than that found for non exposed mussel, used as the control group from Penha (SC). This value is the upper limit allowed by the Brazilian legislation (2.0 mg.kg–1), meaning a risk to those people with a rich diet in mussels.

Levels of non-essential elements in muscle from harp seal ( Phagophilus groenlandicus) and hooded seal ( Cystophora cristata) caught in the Greenland Sea area

The non-essential elements, arsenic, cadmium, mercury and lead, inevitably accumulate in marine top predators such as seals. The concentration of these elements and the essential element selenium, due to its proposed protective properties against mercury toxicity in marine mammals, were measured in muscle, liver and kidney from reproductive active females of harp seal ( Phagophilus groenlandicus) and hooded seal ( Cystophora cristata) caught in the drift ice between Iceland and East Greenland. Arsenic levels were below 1 μg/g w.w. in all analysed samples, and were therefore low compared to other seafood products. The concentrations of arsenic found in the present study were comparable to the results reported in a similar study from 1985. Mean concentrations of total mercury in muscle from the present study were higher than levels in other seafood products. The levels of total mercury from the present study showed a tendency of lower levels in all tissue samples compared to the study from 1985. Methyl mercury displayed a trend of a lower ratio of methyl mercury to total mercury as the concentration of total mercury increased, indicating a demethylation of methyl mercury at high total mercury concentrations (e.g. mercury in liver of hooded seal). The concentration ratio of methyl mercury to total mercury in muscle samples was more than 75%, with total mercury concentration less than 0.5 μg/g w.w., whereas the ratio for liver was as low as 0.2% with a total mercury concentration of 128 μg/g w.w. The molar concentration ratios of selenium to mercury showed that selenium was present in a molar surplus to mercury in all tissues with low mercury concentration. However, there seemed to be a general mobilisation of selenium in liver and kidney tissues of harp seal and hooded seal, whereas an extraordinary mobilisation seemed to take place at hepatic mercury concentrations exceeding 50 μg/g w.w. The mean concentrations of lead in muscles in the present study were higher than in fish and other seafood products from the Barents Sea. The lead concentrations from the present study were lower than levels reported in the 1985 study. However, the levels of the non-essential elements analysed in muscle from the two seal species in the present study should not prevent the use of seal meat in human nutrition.

Impact of Automobile Exhaust on Levels of Lead in a Commercial Food From Bus Terminals

The impact of automobile exhaust on the levels of lead in commercially produced and sold white bread at bus terminals in Lagos Nigeria were assessed. Total lead concentrations by Atomic Absorption Spectrometry were carried out. The mean concentration of lead in foods across the sites (T1-T10) ranged from 0.01-0.025 µgg(-)(1); 0.01-0.03 µgg(-)(1); 0.015-0.035 µgg(-)(1) and 0.005-0.025 µgg(-)(1) for the first second third and fourth periods of sampling respectively. The overall mean concentration of the metal varied between 0.015-0.26 µgg(-)(1) across the sampled sites. The analytical protocol was validated through the quality assurance experiment with quantitative recovery of 92.5% and C.V of 5% which was considered applicable for routine analyses of food samples. The metal was detected in over 80% of the 160 samples that were collected and analyzed. (authors)

Biomonitoring of Lead in Atmospheric Environment of An Urban Center of the Ganga Plain, India

Monitoring of atmospheric lead from the Dalbergia sissoo tree was undertaken at Lucknow urban centre of the Ganga Plain, India. A total of 26 leaf samples were collected in spring, monsoon and winter seasons from 16 sampling sites and was analysed by Atomic Absorption Spectrophotometry method. Lead concentrations were low in spring season, increased in monsoon to winter seasons and range from 2.1 to 28.2 microg/g (dry wt.). This accumulative response of lead in the tree leaves is directly linked with the exposure time of automobile emission that is considered to be the predominant source for it. Highway localities show higher lead concentrations by a factor of 2 as compared to urban localities. Highest concentration was recorded at Sitapur Road (National Highway No. 24) in winter season. A linear quantitative relationship between urban air-lead levels and lead-in-the Dalbergia sissoo leaves is used to infer the qualitative assessment of present day atmospheric lead pollution. Reported results suggest a drastic reduction in mean lead concentration in Lucknow urban air from 1.32 microg/m3 in 1994 to 0.19 microg/m3 in 2002. Similarly, mean lead concentration in the tree leaves during winter season also dropped from 17.9 microg/g in 1994 to 8.1 microg/g in 2004. Despite of increasing urban population, urban area, vehicle population and traffic density, the introduction of unleaded-petrol (vehicular fuel) keeps lead level in the urban environment of Lucknow much lower than the past. Like Lucknow, other urban centres of the Ganga Plain are also on way to the exponential increase in pressure of urbanization. An appropriate urban public transport planning is required to provide healthy atmospheric environment for millions of people especially future young generation.

Concentration of Trace Metals (Lead, Iron, Copper and Zinc) In Crops Harvested in Some Oil Prospecting Locations in River State, Nigeria

Concentrations of the trace metals lead, iron, copper and zinc were estimated in crops harvested in some oil prospecting locations in Rivers State, Nigeria. The locations were; Agbada-Aluu (AA), Ebocha (EB), Idu Ekpeye (IE), Obagi (OB) and Trans Amadi Layout (TA), with the Teaching and Research Farm of Rivers State University of Science and Technology, Port Harcourt as control. Crops investigated were cassava (Manihot esculenta), cocoyam (Colocasia esculenta), okra (Hibiscus esculentus), pumpkin leaves (Telfairia occidentalis) and waterleaf (Talinum traingulare). Results of the mean lead concentrations were from 1.1µg/g in cocoyam to 9.1 µg/g in okro, showing higher trends in the industrialized areas. While cocoyam had the lowest lead concentration, the concentration rest of the crops did not differ significantly from one another. Crops from locations TA, OB, IE and EB had significantly higher concentrations of lead, although IE, AA and TF were not significantly different from one another. Mean concentrations of iron were between 40 µg/g in cassava from TF, and 651 µg/g in pumpkin leaves from TA - the industrial base of Rivers State - reflecting a high level of pollution from the various industries in that location. Differences in concentration of iron in crops showed pumpkin leaves to have the highest level of iron, followed by the other green vegetables – waterleaf and okra - although no significant differences occurred between okra, cocoyam and cassava. Copper concentrations were between 4.4 µg/g in cocoyam from locations TF and 23 µg/g in pumpkin leaves from TA. Pumpkin leaves had the highest concentrations of copper, followed by okra, then waterleaf, with cocoyam and cassava having the least significant levels. Zinc concentrations in crops were between 29 µg/g in cocoyam from TF to 240 µg/g in pumpkin leaves from EB. Pumpkin leaves and okra contained the highest levels of the metal, followed by waterleaf, then cassava and finally cocoyam. In terms of location, TA, OB and EB had the highest concentrations in crops, the least occurring in TF and AA. These results reflect higher concentrations of metals in crops from the industrialized locations, with the green vegetables, particularly pumpkin leaves, having the highest uptake, while cocoyam invariably had the least. These findings give cause for concern, particularly as heavy metals are bio-accumulative in the system and portend a serious health risk to man and animals.

Effect of the mother's consumption of traditional Chinese herbs on estimated infant daily intake of lead from breast milk

Infant exposure to lead through breast milk is of special concern because breast milk is considered the best food source for infants under 6 months. In this study, a total of the mothers provided colostrum samples once in the early postpartum period, but only 16 of them provided breast milk weekly at 1–60 days postpartum. The geometric mean of lead concentrations in all colostrum samples ( n=72) was 7.68±8.24 μg/L. The concentration of lead in the breast milk of the consumption group (the mothers who consumed traditional Chinese herbs) was 8.59±10.95 μg/L, a level significantly higher than the level of 6.84±2.68 μg/L found in the control group (mothers who did not consume traditional Chinese herbs). In the consumption group ( n=9), the mean concentration of lead in the breast milk decreased with days postpartum, from 9.94 μg/L in colostrum to 2.34 μg/L in mature milk. We found the highest daily lead intake in infants at birth, and the level gradually decreased after the first month. We used an estimation of the hazard index (HI) to analyze the health risk of infants. In total, 5.7% (2 out of 35) of the HI estimates exceed 1.0 for the consumption group. In conclusion, the consumptions of traditional Chinese herbs by the mothers in this study significantly affected the body burden of lead in their infants.

Longitudinal patterns in benthic communities in an urban stream under restoration

Okeover Stream, on the University of Canterbury campus in Christchurch, New Zealand, has been the subject of restoration efforts since 1998. Our study focused on quantifying the response of this urban stream to current restoration efforts. Initially, physico‐chemical conditions and biological communities at three sites along the Okeover Stream were compared with three physically similar sites on each of nearby Waimairi Stream and Avon River. General physical and chemical parameters were similar in all streams with circum‐neutral pH, specific conductivity ranging from 167 to 173 μS/cm, dissolved oxygen ranging from 9.0 to 9.2 mg/litre, low turbidity, and similar hydrological conditions. However, analysis of heavy metals in the sediment showed mean lead (Pb) concentrations in Okeover and Waimairi Streams exceeded ANZECC ISQG‐low trigger values (86.9 and 83.7 mg/kg, respectively), whereas Avon River sediment Pb levels (27.3 mg/ kg) were below trigger values. Benthic taxonomic richness did not differ significantly among the three streams. However, Okeover Stream community was dominated by the amphipod Paracalliopefluviatilis, whereas in Waimairi Stream and Avon River the gastropod snails Potamopyrgus antipodarum and Physella acuta were the dominant benthic fauna. A further assessment made at six sites along 1200 m of Okeover Stream showed no distinct longitudinal patterns in physical or chemical conditions, but there was a strong pattern in benthic macroinvertebrate communities. Taxonomic richness and caddisfly diversity increased downstream, with twice as many taxa at the most downstream site than the uppermost sampling site. In upper reaches, copper (Cu), Pb, and zinc (Zn) concentrations in sediments all exceeded ANZECC ISQG‐low trigger values. Despite ongoing restoration efforts in Okeover Stream, sedimentation, the presence of high heavy metal concentrations, intermittent flows in headwaters, and possible barriers to adult recolonisation seem to be having a continuing negative impact on benthic communities, especially in the headwaters.

High levels of blood lead in griffon vultures (Gyps fulvus) from Cazorla natural park (southern Spain)

The blood lead of 23 griffon vultures (Gyps fulvus) trapped in 2003 was analyzed in order to evaluate exposure to lead in the vulture population of Cazorla Natural Park (in southern Spain). In 2001 the use of leaded gasoline in vehicles was banned in the European Union; however, lead ammunition is still used in Spain in big-game hunting for red deer, fallow deer, mouflon, and wild boar, which are ingested by vultures from September to March. The mean concentration of lead in blood was 43.07 +/- 31.96 microg/dL with a range of 17.39-144.80 microg/dL. Only two vultures had lead levels below 20 microg/dL, and two others had blood lead concentrations close to 150 microg/dL. In view of the results, we think the population of vultures from Cazorla Natural Park is suffering subclinical exposure to lead, with some individuals exposed to high toxicity risk. We concluded that ingestion of lead in the metallic form alone is sufficient to produce these blood lead concentrations, and we recommend the prohibition of lead ammunition for big-game hunting in order to preserve the vulture population.

Spatial Distribution of Lead in Enamel and Coronal Dentine of Wistar Rats

Lead is one of the most hazardous environmental toxins known. The assessment of lead in dental hard tissues is important in the understanding of its toxic effects on oral tissues and in estimating exposure and body burden in individuals exposed to lead from the environment. However, current information on the uptake and distribution of lead in enamel and dentine is limited. The aim of this project was to study, at high resolution, the spatial distribution of lead in enamel and coronal dentine using an experimental rat model. A dose of 40 mg/L of lead nitrate was administered to pregnant female rats during the periods of gestation and lactation through drinking water. First mandibular molar teeth were removed from their 15-d-old pups and the distribution of lead was studied using a nuclear microprobe (NMP). The distribution of lead in enamel and coronal dentine showed four distinct zones with significantly different mean lead concentrations (p<0.05). High levels of lead were observed in the superficial regions of enamel and in the dentine directly adjacent to the pulp. Additionally, the results confirmed that the NMP is capable of mapping the distribution of lead in teeth at micron resolutions with a detection limit of approx 1 microg/g.

Spatial distribution of lead in the roots of human primary teeth

Lead remains one of the most hazardous metals in our environment. The concentrations of lead in coronal dentine and enamel have previously been reported but limited information is available regarding lead levels in radicular dentine and cementum. This study reports the distribution of lead in 26 roots of 16 human maxillary primary teeth from seven individuals. In addition, calcium and phosphorous concentrations were also measured to detect any variations in the degree of mineralization in different regions of the roots. The mean lead concentration in these roots was 1.67±1.43 μg/g, which is comparable to other studies. In all cases there were higher lead concentrations in the apices of non-resorbed roots of primary maxillary teeth relative to middle and cervical regions. The findings reported here are of potential significance during the process of physiological root resorption whence periapical tissue may be exposed to higher levels of lead.

Levels of heavy metals in outdoor and indoor dusts in Muscat, Oman

The concentrations of lead, copper, nickel, zinc and chromium in outdoor and indoor dusts collected from different sites in Muscat, Oman, were determined by flame atomic absorption. Results showed a wide range of concentrations, the means in the outdoor dust being, 65 ± 50, 124 ± 316, 47 ± 45, 930 ± 666 and 64 ± 26 mg kg− 1 for lead, zinc, copper, nickel and chromium, respectively. The 2001 Omani phasing out of leaded fuel resulted in low levels of lead in outdoor dust compared to those reported in the literature. Outstanding was the high nickel concentration in outdoor dust when compared to that in the literature, the reason being natural soil pollution due to the local geology of the northern parts of Oman. The concentrations of chromium, copper and zinc are lower than or comparable to these in other cities around the world. The results also showed that the industrial activities in Muscat do not contribute significantly to metal pollution in street dusts. On the other hand, the mean concentrations of lead, zinc, copper, nickel and chromium in indoor dust were 108 ± 65, 753 ± 1162, 108 ± 91, 130 ± 125 and 34 ± 14 mg kg− 1, respectively. In general, zinc and nickel levels are higher than those reported in the literature while lead, copper and chromium levels are lower or comparable. When outdoor and indoor dusts were correlated, the ratios between indoor–outdoor mean concentrations revealed that lead, zinc, and copper were generated internally, while nickel and chromium were from external sources.

PHYSICO-CHEMICAL STUDIES OF SOIL ALONG THE BANKS OF MILI SHALLOW STREAM IN NNEWI, ANAMBRA STATE OF NIGERIA FOR EVIDENCE OF INDUSTRIAL POLLUTION

The physico-chemical properties of soils along the banks of Mili shallow stream in Nnewi, Anambra State of Nigeria was investigated for possible evidence of industrial pollution. The parameters investigated include pH, chloride, nitrate, sulphate, phosphate, Hydrocarbon, alkaline and heavy metal contents of the soil extracts and digests. The data were compared with those of two control stations at Nza Ozubulu and Uzoakwa Ihiala of the neighboring towns. The pH of soils from banks of the Mili stream sampling stations have values less than 5, indicating that soil acidity is wide spread along the banks of Mili stream. Hydrocarbon and lead contamination of soil along some parts of the banks of Mili stream was found to have occurred. Thus, a mean lead concentration of 11.9 ± 9.0mg/kg was recorded. Hydrocarbon concentration as high as 30.1 mg/kg of soil was recorded around Resources Improvement and Manufacturing Company Limited (Rimco). Statistical analysis was carried out on the data and is concluded that there is evidence of soil contamination along the banks of Mili Ele and Rimco industrial parts of the Mili stream. KEY WORDS: Industrial pollution, monitoring, physico-chemical parameters, soils, Nnewi. Global Jnl Pure & Applied Sciences Vol.10(1) 2004: 111-119

Lead levels in primary teeth of children living in Mexico City.

The aim of this study was to discover the lead concentration in primary teeth extracted in the peripheral clinics of the Faculty of Dentistry, UNAM (Mexico City). One hundred healthy primary teeth were collected from 2 to 13-year-old children (52 girls and 48 boys). Sixty-six were maxillary teeth and 34 were mandibular teeth. Lead concentrations were measured by Graphite Furnace Atomic Absorption Spectrophotometry. Our results indicate that lead concentration in the 10-13-year-old group (7.7 micro g/g(-1)) was higher than in the other groups. Geometric mean lead concentration was higher in girls than in boys (7.3 micro g/g(-1) and 6.3 micro g/g(-1), respectively). Maxillary teeth had higher lead concentrations than mandibular teeth and primary canines showed the highest mean lead concentration followed by incisors and molars. Teeth from children living in the south-east area (which according to the Mexico City's Pollution Center data is the more polluted area), presented the highest lead concentration but no statistically significant difference was found among teeth from the different areas. Our results suggest that age, gender and place of residence are not related to the lead concentration in human primary teeth. This fact seems to indicate the ubiquitous presence of lead in the whole atmosphere of Mexico City and suggests that zones of residence do not appear to influence tooth lead concentration.

Lead in Playground Soil: Exposure Estimation of Children via Ingestion and Contamination Source

Lead exposure of children via soil ingestion has never been closely examined in Japan. We determined the lead concentrations in sand and soil samples collected from some public playgrounds in Tokyo Metropolitan Area and estimated lead intake via soil ingestion among children. The mean lead concentration of the soil of 149μm fraction was 46.4μg/g; lead concentrations of play area soil and sand samples (149μm) collected from 25 playgrounds ranged from 11.7μg/g to 248μg/g. An average daily intake of 9.28μg lead was estimated; this amount of lead intake via soil ingestion alone covers 14% of the Provisional Tolerable Weekly Intake (PTWI) of 25μg/kg of body weight set by FAO/WHO. Moreover, the weekly lead intake through soil ingestion could be as high as 72% of PTWI when children ingest soil containing 200μg/g lead. Stable isotope ratios (IRs) analysis of selected soil samples and comparison with the IRs of probable sources were carried out. The IRs of soil samples with lead concentrations higher than 100μg/g had a similar distribution to the gasoline-lead used in Japan, indicating that atmospheric particulates deposited in the past remain in surface soil despite the fact that leaded-gasoline has not been used in Japan for transportation since the 1980s.

Blood lead concentration and delayed puberty in girls.

Environmental lead exposure has been linked to alterations in growth and endocrine function. It is not known whether such exposure affects pubertal development. We analyzed the relations between blood lead concentration and pubertal development among girls (defined as females 8 to 18 years of age) who were enrolled in a cross-sectional study (the third National Health and Nutrition Examination Survey) in which race was self-reported or proxy-reported: 600 were non-Hispanic white, 805 were non-Hispanic African-American, and 781 were Mexican-American girls. Puberty was measured on the basis of the age at menarche and Tanner stage for pubic-hair and breast development. Geometric mean lead concentrations were less than 3 microg per deciliter (0.144 micromol per liter) in all three groups. As compared with concentrations of 1 microg per deciliter (0.048 micromol per liter), lead concentrations of 3 microg per deciliter were associated with decreased height (P<0.001), after adjustment for age, race, and other factors, but not with body-mass index or weight. Blood lead concentrations of 3 microg per deciliter were associated with significant delays in breast and pubic-hair development in African-American and Mexican-American girls. The delays were most marked among African-American girls; in this group, the delays in reaching Tanner stages 2, 3, 4, and 5 associated with a lead concentration of 3 microg per deciliter as compared with 1 microg per deciliter were 3.8, 5.3, 5.8, and 2.1 months, respectively, for breast development and 4.0, 5.5, 6.0, and 2.2 months, respectively, for pubic-hair development; the associated delay in age at menarche was 3.6 months. In white girls, there were nonsignificant delays in all pubertal measures in association with a lead concentration of 3 microg per deciliter. These data suggest that environmental exposure to lead may delay growth and pubertal development in girls, although confirmation is warranted in prospective studies.

Effects of mining activities on heavy metal concentrations in water, sediment, and macroinvertebrates in different reaches of the Pilcomayo River, South America.

From 1997 until 1999 the extent and the ecological effects of zinc, copper, lead, and cadmium pollution were studied in different reaches of the South American Pilcomayo River. A comparison of metal concentrations in water, sediment, and chironomid larvae, as well as the diversity of macroinvertebrate species, was made between sites near the origin of the Pilcomayo River, with hardly any mining activities, sites in the Potosí region, with intensive mining, and sites located 500 km or further downstream of Potosí, in the Chaco plain. Samples were also collected in an unpolluted river (Cachi Mayu River) and in the Tarapaya River, which is strongly contaminated by mine tailings (1000 tons a day). The upper parts of the Pilcomayo River are strongly affected by the release of mine tailings from the Potosí mines where mean concentrations of lead, cadmium, copper, and zinc in water, filtered water, sediment, and chironomid larvae were up to a thousand times higher than the local background levels. The diversity of the benthic macroinvertebrate community was strongly reduced in the contaminated parts; 97% of the benthic macroinvertebrates consisted of chironomid larvae. The degree of contamination in the lower reaches of the river, however, was fairly low because of sedimentation processes and the strong dilution of mine tailings with enormous amounts of clean sediment from erosion processes. Analysis of sediment cores from the Ibibobo floodplain, however, reveal an increase of the heavy metal concentrations in the lower reaches since the introduction of the contaminating flotation process in the mine industry in 1985.

Uptake and distribution of lead (Pb) and cadmium (Cd) in the freshwater crab, Potamonautes perlatus (Crustacea) in the Eerste River, South Africa

The uptake and distribution of lead (Pb) and cadmium (Cd) in thefreshwater crab, Potamonautes perlatus in the Eerste River,South Africa were studied seasonally over two years by comparingconcentrations in crabs, water and sediment in two localities, one upstream and one downstream from the town of Stellenbosch. Lead and cadmium concentrations in whole crabs of different sizeclasses as well as concentrations in various organs and tissues were determined by atomic absorption spectrometry. Data on physical, chemical and bacteriological features are also presented. The mean Zn concentration in the sediment of the downstream locality (77.5 ± 38.4 μg g-1) was significantly higher than in the less polluted upstream locality(44.7 ± 32.8 μg g-1) whilst the manganese concentration of the sediment was significantly higher in the upstream locality. The gonads (mean Pb 23.4, range 0.1-125.0 μg g-1; mean Cd 5.3, range 0.1-22.2 μg g -1) and carapace (mean Pb 23.4, range 0.7-327.6 μg g-1; mean Cd 4.0, range 0.4-18.5 μg g-1) contained thehighest concentrations of both metals irrespective of season orlocality. For both Pb and Cd significant differences (p < 0.05, Student's t-test) were found between the metal content of different organs. The gonads had the highest and the digestiveglands the lowest concentrations of both heavy metals.Results indicated that anthropogenic activities did not influencesediment and water concentrations significantly. Smaller crabs accumulated more lead and cadmium than larger crabs with all crabs having significantly higher concentrations than both waterand sediment. No significant differences in mean concentrationsof lead and cadmium in whole crabs or organs were found between the two localities. Although body loads for both metals did notreflect prevailing environmental levels of these metals reliably,the crabs may still be used to monitor bioavailability over time.

Biomarkers of Renal Effects in Children and Adults with Low Environmental Exposure to Heavy Metals

The health effects of chronic exposure to heavy metals such as lead, cadmium, and mercury are widely documented, yet few data exist about the renal impact of low environmental exposure to these metals, particularly in children. The aim of this study was to assess renal parameters in children and adults living in an environment known for its past heavy metal contamination around two nonferrous smelters in northern France (Noyelles-Godault and Auby) and to compare their results with age and gender-matched controls living in neighboring municipalities with unpolluted soil (total: 400 children, 600 adults, sex ratio = 1). The integrity of renal function was assessed by measuring the urinary excretion levels of total protein, albumin, transferrin, g 2 -microglobulin, retinol-binding protein, brush border antigen, and the enzyme N-acetyl- g -D-glucosaminidase (NAG). The mean blood concentrations of lead (Pb-B, children h 42.2 w /L, adults h 71.3. w /L) and of cadmium (Cd-B, children h 0.52 w g/L, adults 0.86 w g/L) were all relatively low, indicating a low uptake of these heavy metals from the environment despite relatively high levels in soil (between 100 and 1700 ppm for lead and 0.7 to 233 ppm for cadmium). Pb-B levels were, however, significantly increased in boys, girls, and women--but not men--living in the polluted area. Boys, men, and women living in the polluted area had also on average higher Cd-B levels. The concentrations of mercury in urine (Hg-U) were by contrast similar in control and exposed groups. None of the renal parameters studied showed a significant difference between control and exposed groups. The influence of heavy metals on renal parameters was further assessed by stepwise multiple regression, testing Pb-B, Cd-B, Hg-U, age, gender, body mass index (BMI), urinary creatinine levels, and area of residence as predictors in both children and adults, including first-order metal interaction terms, smoking habits, and alcohol consumption in adults. The only positive correlation was found between the urinary excretion of NAG activity (standardized for BMI and urinary creatinine) and Cd-B levels when taking the whole children population, indicating that even low cadmium burdens may produce subtle effects on the proximal tubule in children, although deleterious consequences are unlikely should exposure not increase. However, in the absence of other positive findings even after studying the smaller subgroups with higher levels of heavy metals, these results are clearly indicative of the minimal renal impact of living around nonferrous smelters that are currently complying with pollution regulations, even when soil contamination is still high.