Contribution to the study of drinking water, danube water and biocenose contamination with chlorinated insecticides

The present paper deals with the methods of determination of BHC isomers, of DDE, DDT and HCB in waters, drinking and surface waters from the Danube; in two sorts of fish living in the Danube: herbivorous (Cyprinus carpio L., Abramis ballerus L., and Chondrostoma nasus L.) and carnivorous (Esox lucius L., Lepomis gibbosus L., Aspius asptus L. and Perca fluviatilis L.); in sediment and water plants using GLC and TLC.In the period 1971–1974, the mean concentrations of the compounds studied were: in drinking water from 0.00 to 0.12 μg/1; in the waters from the Danube from 0.006 to 0.197 μg/1; in predominantly herbivorous fish from 0.00 to 2.58 mg/kg; in sediment from 0.01 to 2.11 mg/kg; and in water plants from 0.002 to 0.032 mg/kg.The mean levels of the studied compounds found in the fish were 1000–10,000 times higher than those of the water. Comparing the average contents of the BHC isomers as well as of DDT and DDE in fish, considerably higher concentrations of DDT and DDE were found as compared with the BHC levels, mainly in carnivorous fish. Differences in the contents of the insecticides studied are due to their different cumulative properties.     

Dietary intake of hexachlorobenzene in Catalonia, Spain

To assess the dietary intake of hexachlorobenzene (HCB) by the population of Catalonia, Spain, a total-diet study was carried out. Concentrations of HCB were determined in food samples randomly acquired in seven cities of Catalonia between June and August 2000. A total of 11 food groups were included in the study. HCB levels were determined by HRGC/HRMS. Estimates of average daily food consumption were obtained from recent studies. HCB intake was estimated for five population groups: children (aged 4 to 9 years), adolescents (aged 10 to 19 years), male and female adults (aged 20 to 65 years), and seniors (aged >65 years). In general, HCB residues in foods were rather low excepting dairy products with a mean concentration of 0.869 ng/g wet weight. Total dietary intakes of HCB (microgram per kilogram body weight/day) were the following: children (0.0064), adolescents (0.0031), female adults (0.0025), male adults (0.0024) and seniors (0.0019). All these values are considerably lower than the WHO tolerable daily intake (TDI), which is 0.17 microg kg(-1) day(-1) for non-cancer effects and 0.16 microg kg(-1) day(-1) for neoplastic effects in humans.     

Thermal destruction of PCB and hexachlorobenzene

PCB and hexachlorobenzene are considered to be two environmental compounds of concern that are most difficult to destroy. This report describes experiments that have been carried out in order to obtain basic data for appraisal of the risks involved in the thermal destruction of PCB and hexachlorobenzene.The investigation indicates that it is possible to destroy PCB by incineration provided that the transit time is sufficiently long. In the pilot scale incinerator used, a transit time of more than two seconds was required to obtain a residue of PCB that was less than 100 mg/kg PCB fed into the incinerator. It was not possible to determine any fixed relationship between the temperature and the PCB residue within the temperature range examined (675–1000°C). The investigation also shows that hexachlorobenzene is formed in association with the combustion of PCB and that the rate of formation increases at high temperatures (35 mg HCB/kg PCB at 1000°C).A temperature of 950°C is needed for the destruction of hexachlorobenzene if the residue is to be less than 100 mg HCB/kg HCB. At 800°C, with a transit time of about 2 s, there is a residue of approximately 1200 mg/kg.     

Exposure to hexachlorobenzene through fish and seafood consumption in Catalonia, Spain

The concentrations of hexachlorobenzene (HCB) were analyzed by HRGC/HRMS in 42 composite samples of the 14 most consumed marine species (sardine, tuna, anchovy, mackerel, swordfish, salmon, hake, red mullet, sole, cuttlefish, squid, clam, mussel, and shrimp) in Catalonia, Spain. The daily intake of HCB associated with this consumption was also estimated for four age groups of the population of Catalonia: children, adolescents, adults and seniors, which were in turn divided according to sex. The highest HCB levels were found in salmon and mackerel: 1.68 and 0.80 ng/g of wet weight, respectively, whereas the lowest HCB levels were found in cuttlefish, mussel, and shrimp (0.02, 0.03, and 0.04 ng/g of wet weight, respectively). In general terms, these results are within the range of data reported in recent years by a number of authors. The highest and lowest HCB intake (ng/day) corresponded to female adults (13.3) and girls (4.0), respectively. For most age/sex groups, salmon and sole were the species showing the highest contribution to HCB intake. When HCB intake was calculated according to the average body weight of the individuals in each group, the highest and lowest values corresponded to boys (0.32 ng/kg/day) and female adolescents (0.14 ng/kg/day). For all groups, HCB intake from fish and seafood consumption was considerably lower than the WHO tolerable daily intake (TDI), for non-cancer effects and for neoplastic effects in humans.     

Residuals of beta-hexachlorocyclohexane, dichlorodiphenyltrichloroethane, and hexachlorobenzene in serum, and relations with consumption of dietary components in rural residents in Japan

To estimate levels of organochlorine residuals in the Japanese population and the contribution of dietary factors to these levels, we determined serum levels of beta-hexachlorocyclohexane (beta-HCH), hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE) and p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) in 41 volunteers (14 men and 27 women) in a rural area of Northern Japan. These organochlorine levels were measured using gas-chromatography mass-spectrometry. By a self-administered dietary history questionnaire, the usual dietary intake was estimated. Their median levels (range) were as follows: beta-HCH, 0.50 (0.05-1.50); HCB, 0.20 (0.02-0.70); and total DDT (p,p'-DDE + p,p'-DDT), 5.0 (0.9-31.0) ng/ml serum. Levels of p,p'-DDD were detected in only seven subjects (0.05-0.6 ng/ml serum). The beta-HCH levels were increased with rice and milk intakes, but the least squares means were not simply increased according to the quartile of the intakes. Concerning HCB, fish intake showed a borderline significant correlation (0.20, P = 0.052). In terms of total DDT, intakes of meat, fish, vegetable and milk showed a positive relationship, although none of them provided statistically significant results. No other statistically significant relation between any organochlorines and any food intakes examined was observed in this study. The present study suggests that organochlorine compounds are transported into the human body via foods in the Japanese population. Their effects on health should thus be investigated and monitored.     

Seasonality of diffusive exchange of polychlorinated biphenyls and hexachlorobenzene across the air-sea interface of Kaohsiung Harbor, Taiwan

Gaseous and dissolved concentrations of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) were measured in the ambient air and water of Kaohsiung Harbor lagoon, Taiwan, from December 2003 to January 2005. During the rainy season (April to September), gaseous PCB and HCB concentrations were low due to both scavenging by precipitation and dilution by prevailing southwesterly winds blown from the atmosphere of the South China Sea. In contrast, trace precipitation and prevailing northeasterly winds during the dry season (October to March) resulted in higher gaseous PCB and HCB concentrations. Instantaneous air-water exchange fluxes of PCB homologues and HCB were calculated from 22 pairs of air and water samples from Kaohsiung Harbor lagoon. All net fluxes of PCB homologues and HCB in this study are from water to air (net volatilization). The highest net volatile flux observed was + 172 ng m^− 2 day^− 1 (dichlorobiphenyls) in December, 2003 due to the high wind speed and high dissolved concentration. The PCB homologues and HCB fluxes were significantly governed by dissolved concentrations in Kaohsiung Harbor lagoon. For low molecular weight PCBs (LMW PCBs), their fluxes were also significantly correlated with wind speed. The net PCB and HCB fluxes suggest that the annual sums of 69 PCBs and HCB measured in this study were mainly volatile (57.4 × 10³ and 28.3 × 10³ ng m^− 2 yr^− 1, respectively) and estimated yearly, 1.5 kg and 0.76 kg of PCBs and HCB were emitted from the harbor lagoon surface waters to the ambient atmosphere. The average tPCB flux in this study was about one-tenth of tPCB fluxes seen in New York Harbor and in the Delaware River, which are reported to be greatly impacted by PCBs.     

Cu, Pb and Zn contamination in Nuuanu watershed, Oahu, Hawaii

Trace metal contamination in urban aquatic ecosystems in Hawaii is a significant problem, especially in terms of Cu, Pb, and Zn. These trace metals are linked to automobile usage. An in-depth study was designed to determine the influence of road sediments and storm sewers on bioavailable (0.5 M HCl) trace metal concentrations in bed sediments of Nuuanu stream, Oahu. Lead was the most enriched trace metal in the watershed. Compared to baseline Pb concentrations of <3 mg/kg, road sediments averaged 186 mg/kg, with a maximum value of 3140 mg/kg. Stream bed sediments had average Pb values of 122 mg/kg, with a maximum of 323 mg/kg. Al-normalized enrichment ratios (ERs) for the <63 microm fraction indicated that the watershed was significantly polluted in the lower, urbanized reaches, with maximum ER values of 560 and 94 for Pb in road sediments and stream sediments, respectively. Median ER values for Cu, Pb, and Zn in stream sediments were 2, 36, and 5, respectively. Rainfall events prior to sediment sampling masked any influence that storm sewer outlets might have had on the localized spatial distribution of metals associated with bed sediments. However, there was a general pattern of increasing trace metal concentrations downstream as the fluvial network traversed residential areas and commercial, highly trafficked areas in the lower portions of the watershed.     

Lead contamination in tap water of households with children in Lower Saxony, Germany

Lead has numerous acute and chronic adverse effects on human beings. This is especially true for infants and children. The main path of lead ingestion in children can be different according to housing and living situation. The intake of lead through drinking water is commonly due to metal corrosion. The users plumbing can be an important factor. In recent years, many lead pipes in Germany have been replaced by pipes made of an alternative material. The aim of this study is to assess the present state of drinking water contamination and the resulting exposure of infants to lead. For this purpose mothers of new-born babies were offered a free examination of their drinking water. After a written declaration of consent had been obtained and after the infant in question had reached an age of 3 months, a stagnation sample of cold tap-water after overnight stagnation together with a random daytime sample was obtained from the family. The collected samples were analysed by atomic absorption spectrometry for their lead concentration. In total, 1485 samples from households were collected. Of the 1434 stagnation samples, 3.1% had lead concentrations greater than 0.01 mg/l (recommended limit of the WHO) and 0.6% had concentrations above the limit of the German drinking water regulation (0.04 mg/l). The values for the 1474 random daytime samples were 2.1% above 0.01 mg/l and 0.2% greater than 0.04 mg/l, respectively. By region, the areas Bovenden, Friedland, Duderstadt, Northeim and Rosdorf were particularly affected. The highest measured concentrations of lead in the stagnation samples were 0.11 mg/l and 0.15 mg/l in the random daytime samples, respectively.     

Nitrate contamination of shallow groundwaters in Ontario,Canada

Highly elevated concentrations of NO₃^? have been found in the groundwaters from shallow aquifers at several locations in Ontario. The nitrate is derived either from the fertilizers applied to the agricultural soils, or from industrial point sources, and should be regarded as a major water quality problem. However, the nitrate levels may be reduced by denitrification processes under reducing conditions in the aquifer. The distributions of ammonia, chloride, dissolved oxygen, redox potential, methane, calcium and magnesium are presented and related to the hydrogeochemical changes undergone by the pollutant nitrate during flux along the groundwater flow systems.     

Temperature effect on the elimination of pentachlorophenol,hexachlorobenzene and mirex by rainbow trout (salmo gairdneri)

The elimination rates of pentachlorophenol, hexachlorobenzene and mirex were estimated in rainbow trout that were held at 4, 12 and 18°C for 120 days following a single oral exposure. The results suggested temperature could become an important environmental variable in deriving a coefficient for the elimination component of a contaminant dynamics model. This response would be most applicable for those substances that are eliminated relatively rapidly, and those models that simulate the contaminant dynamics of fish in its natural environment.     

Experimental data and critical review of the occurrence of hexachlorobenzene in the Italian environment

After an introduction on the toxicological and physicochemical characteristics of HCB and its methods of analysis in waters, food, etc., the communication draws a picture of HCB contamination in Italy, as seen from experimental data obtained from 1969 to 1974.The results given refer to samples of surface waters, soils, fauna, cows milk, uncooked and cooked total diets, human fatty tissue. In 120 samples of surface waters HCB was found to be present in 90% at an average level of 2.5 ppt (n.d. 25.1), 40 ppb were found in the soil and as much as 7.2 ppm in the liver of birds found dead. HCB was also found in 63 samples of whole cows milk (100% positive) at an average level of 4.2 ppb (0.2–17.2), while researches on total diets made it possible to evaluate an intake of about 4.2/μg/man/day in the diet of the “average man” (reference body weight: 60kg); this represents 11–12% of the allowable daily intake suggested provisionally by FAO/WHO. Finally HCB was measured in 28 samples of human fatty tissue (100% positive) at an average level of 0.491 ppm (0.126–1.359) in fresh tissue or 1.021 ppm (0.311–2.577) referred to the fat extracted.All these data have made it possible to calculate some indices of bioconcentration of the product and comparisons are made with the data obtained in other countries.In conclusion, attention is drawn to the fact that distribution of HCB in the environment in Italy and the levels found, are not consistent with its rather limited uses in the agricultural sector (dressing of seeds), so it is likely that other sources contribute to the pollution. The following are indicated among the possible sources: the presence of HCB as an impurity in other pesticides, its formation during the synthesis of products of the chemical industry and its presence in industrial wastes.     

Groundwater contamination associated with a potential nuclear waste repository at Yucca Mountain,USA

The groundwater contamination originating from a potential nuclear waste repository at Yucca Mountain, USA, is evaluated in a three-dimensional flow transport simulation. The model has 833,079 elements and includes both the saturated and unsaturated zone. Vertical grid spacing is 20 m in the saturated zone and 40 m in the unsaturated zone. Spacing in the x and y directions is 250 m in both the saturated and unsaturated zone. The simulation period is 1,000,000 years. Three scenarios with different saturation values (0.056, 0.1 and 0.18) for Dirichlet conditions at the top of the model and different permeabilities for the total model are calculated. The results differ from previous calculations conducted with a combination of one-dimensional models for the saturated zone and uncoupled models for the unsaturated zone. Since one-dimensional models produce averaged values for the three-dimensional space, they necessarily produce a relatively low radioactive dose. In contrast, the peak dose for the 250 x 250 x 20-m cells in the three-dimensional space is relatively high but closer to the risk an individual is exposed to within a reasonably small area.

     

Occurrence of arsenic contamination in Canada: sources, behavior and distribution

Recently there has been increasing anxieties concerning arsenic related problems. Occurrence of arsenic contamination has been reported worldwide. In Canada, the main natural arsenic sources are weathering and erosion of arsenic-containing rocks and soil, while tailings from historic and recent gold mine operations and wood preservative facilities are the principal anthropogenic sources. Across Canada, the 24-h average concentration of arsenic in the atmosphere is generally less than 0.3 microg/m3. Arsenic concentrations in natural uncontaminated soil and sediments range from 4 to 150 mg/kg. In uncontaminated surface and ground waters, the arsenic concentration ranges from 0.001 to 0.005 mg/L. As a result of anthropogenic inputs, elevated arsenic levels, above ten to thousand times the Interim Maximum Acceptable Concentration (IMAC), have been reported in air, soil and sediment, surface water and groundwater, and biota in several regions. Most arsenic is of toxic inorganic forms. It is critical to recognize that such contamination imposes serious harmful effects on various aquatic and terrestrial organisms and human health ultimately. Serious incidences of acute and chronic arsenic poisonings have been revealed. Through examination of the available literature, screening and selecting existing data, this paper provides an analysis of the currently available information on recognized problem areas, and an overview of current knowledge of the principal hydrogeochemical processes of arsenic transportation and transformation. However, a more detailed understanding of local sources of arsenic and mechanisms of arsenic release is required. More extensive studies will be required for building practical guidance on avoiding and reducing arsenic contamination. Bioremediation and hyperaccumulation are emerging innovative technologies for the remediation of arsenic contaminated sites. Natural attenuation may be utilized as a potential in situ remedial option. Further investigations are needed to evaluate its applicability.     

Seasonal, interannual, and long-term variation in sport fish contamination, San Francisco Bay

This study documents changes in contamination over time at seasonal, interannual, and decadal time scales for sport fish collected in San Francisco Bay. Samples from seven fish species were prepared according to common consumption practices (muscle fillets either with or without skin) and analyzed for trace metals (mercury and selenium) and trace organochlorine contaminants (PCBs, DDTs, chlordanes, and dieldrin). In 2000, sport fish samples exceeded human health screening values for mercury, PCBs, DDTs, selenium, and dieldrin but did not exceed screening values for chlordanes. On a seasonal time scale, white croaker (Genyonemus lineatus) exhibited significantly lower PCB and lipid concentrations in spring, and a general increase in concentrations in other seasons. When monitoring data were compared among 1994, 1997, and 2000, analysis of variance indicated that concentrations of mercury, PCBs, DDTs, and chlordanes varied significantly among years for several fish species. Interannual variation in DDTs often correlated to changes in sampled fish size or lipid content among years. Interannual variation in mercury and PCBs was evident in striped bass (Morone saxatilis) but absent in shiner surfperch (Cymatogaster aggregata), leopard shark (Triakis semifasciata), and white croaker. The higher interannual variability of striped bass contaminant concentrations may result from migratory behavior and wide home ranges. Chlordanes significantly declined between 1994 and 2000 in white croaker and striped bass. Of the historical data analyzed (1986-2000), only DDT concentrations in white sturgeon (Acipenser transmontanus) showed evidence of a significant decline. Neither PCBs nor selenium showed evidence of a trend in white sturgeon. Between 1970 and 2000, mercury concentrations in striped bass showed no evidence of a trend. The absence of recent trends in mercury may result from the presence of widespread and historic sources, with use reductions occurring in the early 20th century. In contrast to mercury, apparent recent declines in fish tissue DDT and chlordane concentrations may result from use curtailment in the 1970s and 1980s.     

The distribution of depleted uranium contamination in Colonie, NY, USA

Uranium oxide particles were dispersed into the environment from a factory in Colonie (NY, USA) by prevailing winds during the 1960s and '70s. Uranium concentrations and isotope ratios from bulk soil samples have been accurately measured using inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) without the need for analyte separation chemistry. The natural range of uranium concentrations in the Colonie soils has been estimated as 0.7-2.1 μg g^− 1, with a weighted geometric mean of 1.05 μg g^− 1; the contaminated soil samples comprise uranium up to 500 ± 40 μg g^− 1. A plot of ²³⁶U/²³⁸U against ²³⁵U/²³⁸U isotope ratios describes a mixing line between natural uranium and depleted uranium (DU) in bulk soil samples; scatter from this line can be accounted for by heterogeneity in the DU particulate. The end-member of DU compositions aggregated in these bulk samples comprises (2.05 ± 0.06) × 10^− 3235U/²³⁸U, (3.2 ± 0.1) × 10^− 5236U/²³⁸U, and (7.1 ± 0.3) × 10^− 6234U/²³⁸U. The analytical method is sensitive to as little as 50 ng g^− 1 DU mixed with the natural uranium occurring in these soils. The contamination footprint has been mapped northward from site, and at least one third of the uranium in a soil sample from the surface 5 cm, collected 5.1 km NNW of the site, is DU. The distribution of contamination within the surface soil horizon follows a trend of exponential decrease with depth, which can be approximated by a simple diffusion model. Bioturbation by earthworms can account for dispersal of contaminant from the soil surface, in the form of primary uranium oxide particulates, and uranyl species that are adsorbed to organic matter. Considering this distribution, the total mass of uranium contamination emitted from the factory is estimated to be c. 4.8 tonnes.     

Mercury contamination associated with small-scale gold mining in Tanzania and Zimbabwe

Mercury contamination associated with small-scale gold mining and processing represents a major environmental and human health concern in Eastern and Southern Africa. Approximately 200,000-300,000 persons are involved in small-scale gold mining activities in Tanzania and > 200,000 persons in Zimbabwe. Mercury (Hg) is used mainly for the processing of primary gold quartz veins and supergene gold mineralizations. Gravimetric material flow analyses show that 70-80% of the Hg is lost to the atmosphere during processing, 20-30% are lost to tailings, soils, stream sediments and water. For every 1 g Au produced, 1.2-1.5 g Hg are lost to the environment. Cumulatively, the anthropogenic Hg released annually into the atmosphere is approximately 3-4 t in the whole Lake Victoria Goldfields of Tanzania and > 3 t in Zimbabwe. Tailings are local 'hot spots' with high concentrations of As, Pb, Cu and Hg. Lateral and vertical dispersion of Hg lost to soils and stream sediments is very limited (laterally < 260 m, vertically < 20 cm). Dispersion of mercury from tailings is low because Hg is transported largely in the elemental, metallic form. In addition, Fe-oxide rich laterites and swamps appear to be natural barriers for the dispersion of metals in soils and streams. Ground and surface water quality data indicate very low dispersion rates during the dry season.     

Environmental and food contamination with PCB's in Japan

In Japan “Yusho”, i.e., poisoning caused by ingestion of rice oil contaminated with PCB's, broke out in October 1968, and produced more than 1200 officially certified cases. Nevertheless, it was only regarded as a kind of food poisoning and its connection with environmental and biological contamination was only imperfectly taken into consideration.Finally, in the autumn of 1970, two study groups, from the Ehime University and the Kyoto City Hygienic Institute, reported on the PCB contamination of salt water and fresh water fishes in Japan. Subsequently many reports about PCB's as an environmental contaminant have been published by several study groups throughout Japan, and nowadays the PCB polluted state of Japan has become rather clearly recognized.This report will present information on environmental, food and human contamination with PCB's in Japan especially also in some typically contaminated local areas, in addition to summarizing some overall aspects of the PCB problem in Japan (e.g., the production, shipment and use of PCB's).     

Composition of bacterial and archaeal communities in freshwater sediments with different contamination levels (Lake Geneva, Switzerland)

The aim of this study was to compare the composition of bacterial and archaeal communities in contaminated sediments (Vidy Bay) with uncontaminated sediments (Ouchy area) of Lake Geneva using 16S rRNA clone libraries. Sediments of both sites were analysed for physicochemical characteristics including porewater composition, organic carbon, and heavy metals. Results show high concentrations of contaminants in sediments from Vidy. Particularly, high contents of fresh organic matter and nutrients led to intense mineralisation, which was dominated by sulphate-reduction and methanogenesis. The bacterial diversity in Vidy sediments was significantly different from the communities in the uncontaminated sediments. Phylogenetic analysis revealed a large proportion of Betaproteobacteria clones in Vidy sediments related to Dechloromonas sp., a group of dechlorinating and contaminant degrading bacteria. Deltaproteobacteria, including clones related to sulphate-reducing bacteria and Fe(III)-reducing bacteria (Geobacter sp.) were also more abundant in the contaminated sediments. The archaeal communities consisted essentially of methanogenic Euryarchaeota, mainly found in the contaminated sediments rich in organic matter. Multiple factor analysis revealed that the microbial community composition and the environmental variables were correlated at the two sites, which suggests that in addition to environmental parameters, pollution may be one of the factors affecting microbial community structure.     

Arsenic and heavy metal contamination of vegetables grown in Samta village,Bangladesh

Drinking of arsenic (As) contaminated well water has become a serious threat to the health of many millions in Bangladesh. However, the implications of contamination of agricultural soils from long-term irrigation with As-contaminated groundwater for phyto-accumulation in food crops, and thence dietary exposure to As, and other metals, has not been assessed previously in Bangladesh. Various vegetables were sampled in Samta village in the Jessore district of Bangladesh, and screened for As, Cd, Pb, Cu and Zn by inductively coupled plasma emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). These local food products are the basis of human nutrition in this region and of great relevance to human health. The results revealed that the individual vegetables containing the highest mean As concentrations microg x g(-1)) are snake gourd (0.489), ghotkol (0.446), taro (0.440), green papaya (0.389), elephant foot (0.338) and Bottle ground leaf (0.306), respectively. The As concentration in fleshy vegetable material is low. In general, the data show the potential for some vegetables to accumulate heavy metals with concentrations of Pb greater than Cd. Some vegetables such as bottle ground leaf, ghotkol, taro, eddoe and elephant foot had much higher concentrations of Pb. Other leafy and root vegetables, contained higher concentrations of Zn and Cu. Bioconcentration factors (BCF) values, based on dry weight, were below 1 for all metals. In most cases, BCF values decreased with increasing metal concentrations in the soil. From the heavily As-contaminated village in Samta, BCF values for As in ladies finger, potato, ash gourd, brinjal, green papaya, ghotkol and snake gourd were 0.001, 0.006, 0.006, 0.014, 0.030, 0.034 and 0.038, respectively. Considering the average daily intake of fresh vegetables per person per day is only 130 g, all the vegetables grown at Samta had Pb concentrations that would be a health hazard for human consumption. Although the total As in the vegetables was less than the recommended maximum intake of As, it still provides a significant additional source of As in the diet.