Consumption of food crops contaminated with heavy metals is a major food chain route for human exposure. We studied the health risks of heavy metals in contaminated food crops irrigated with wastewater. Results indicate that there is a substantial buildup of heavy metals in wastewater-irrigated soils, collected from Beijing, China. Heavy metal concentrations in plants grown in wastewater-irrigated soils were significantly higher (P <= 0.001) than in plants grown in the reference soil, and exceeded the permissible limits set by the State Environmental Protection Administration (SEPA) in China and the World Health Organization (WHO). Furthermore, this study highlights that both adults and children consuming food crops grown in wastewater-irrigated soils ingest significant amount of the metals studied. However, health risk index values of less than 1 indicate a relative absence of health risks associated with the ingestion of contaminated vegetables. Long-term wastewater irrigation leads to buildup of heavy metals in soils and food crops.

The presence of alpha emitting radionuclides in the environment assumes importance since they are found to be carcinogenic. This paper reports the results of an exhaustive and systematic measurement of alpha radioactivity using solid state nuclear track detector (SSNTD) in drinking water in different parts of India covering the entire Ganges Basin - West Bengal, Bihar and Uttar Pradesh where arsenic contamination is severe. The alpha activity in the samples was found in the range of 8 to 800 Bq/l in West Bengal, 90 to 1,000 Bq/l in Uttar Pradesh and 60 to 1,000 Bq/l in Bihar - much higher alpha activity value than MCL value given by US EPA. The concentration of alpha activity has a positive correlation with that of arsenic.

Spatial variations of Carbon Monoxide (CO) are examined in the urban environment of Ouagadougou, Burkina Faso. Focus is given on the variations between urban background, roadside and in-traffic measurements. Results show significant differences between the three methods where average in-traffic values were 2-3 times higher than average roadside values and 10-12 times higher than average background values. During traffic congestions these differences extended up to 6 and 20 times respectively. Results are discussed in relation to human exposure assessments and WHO guidelines.

In recent years, arsenic (As) has received increased attention as humans may be exposed to it through occupational and environmental exposure. Tobacco (Nicotiana tabacum L.) like other crops can uptake this element from the soil, which may lead to human exposure. Here, we report on a survey on arsenic in cured or processed tobacco leaves obtained from Africa, Asia, Europe, South and North America. A total of 1,431 leaf samples of flue-cured, burley, and Oriental tobaccos were obtained from various sampling locations during 2002 to 2004. Arsenic concentration in the samples averaged 0.4 ± 0.6 μg g⁻¹ as determined by inductively coupled plasma-mass spectrometry. Recorded values from most samples showed that concentrations of arsenic were usually found at the lower end of the distribution. Significant differences were found among tobacco types, sampling locations, and crop years. Arsenic concentrations were rather low in the majority of regions investigated, which is compatible with data from the literature. However, sample size was small and sampling geographically restricted. Our results would need to be validated with a larger dataset.

We determined the concentrations and residue patterns of 20 persistent organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs), hexachlorobenzene, dichlorodiphenyltrichloroethanes (DDTs), chlordane-related compounds (CHLs), mirex, dieldrin, endrin, and aldrin, in muscle of rainbow trout from Lake Mashu, Japan. Total concentrations of OCPs varied from 1.0 to 132 ng g-¹ lipid weight. α-HCH was the most prevalent OCP contaminant in the fish muscle. Using the daily fish consumption in Japan (95.2 g), the mean weight of a Japanese adult (50.0 kg), and residual pesticide concentrations, we calculated the estimated daily intakes of γ-HCH, DDTs, CHLs, and dieldrin for humans to be 0.39, 0.48, 0.68, and 0.08 ng kg-¹ day-¹, respectively. Judging from acceptable daily intakes established by the Food and Agriculture Organization of the United Nations and the World Health Organization, we believe that these OCP levels would not adversely affect human health.

The immobilization of lead by the reaction with phosphate bearing materials is a promising remediation method for contaminated soils. Low soluble neo-formed lead-phosphate phases similar to chloropyromorphite [Pb₅(PO₄)₃Cl], can control availability and mobility of lead in the environment, and consequently reduce human exposure, if soils are the main contamination pathway. We used three phosphate source materials [NaH₂(PO₄)₃, commercial superphosphate and phosphate rock] to study lead immobilization in soil and mining waste samples. Products were examined after 1, 3 and 6 months of contact. The samples are from a contaminated area by former Pb mining and smelting activities, in southeastern Brazil, where epidemiological studies showed high lead blood levels in local population. The PBET (physiological based extraction test) bioaccessibility test was used to measure changes in the amount of soluble lead after sample treatment. Results show that the most efficient phosphate source was NaH₂(PO₄)₃, which reduced lead solubility to 92% in acidic gastric conditions after the first month of contact. Superphosphate and phosphate rock also diminished Pb solubility, but the effect was more time dependent. None specific Pb-phosphate phases could be identified by XRD in whole treated samples, but the Pb-Ca-P elemental associations, observed on SEM images and EDS spectra of portions of the samples, combined with the reduced solubility, indicate that more insoluble lead phases were formed after the treatment. Based in these results, the in site phosphate application on soils to induce lead immobilization should be considered as a possible alternative to reduce human exposure at the area.

The present study aims to understand the hydrochemistry vis-à-vis As-exposure from drinking groundwater in rural Bengal. The characteristic feature of the groundwaters are low Eh (range, -151 to -37 mV; mean, -68 mV) and nitrate (range, 0.01-1.7 mg/l; mean, 0.14 mg/l) followed by high alkalinity (range, 100-630 mg/l; mean, 301 mg/l), Fe (range, 0.99-38 mg/l; mean, 8.1 mg/l), phosphate (range, 0.01-15 mg/l; mean, 0.54 mg/l), hardness (range, 46-600 mg/l; mean, 245 mg/l) and sulphate (range, 0.19-88 mg/l; mean, 7.2 mg/l), indicating reducing nature of the aquifer. The land use pattern (sanitation, surface water bodies, sanitation coupled with surface water bodies and agricultural lands) demonstrates local enrichment factor for As/Fe in groundwater. Among these, sanitation is the most prevailing where groundwater is generally enriched with As (mean, 269 μg/l) and Fe (mean, 9.8 mg/l). Questionnaire survey highlights that ~70% of the villagers in the study area do not have proper sanitation. This demonstrating the local unsewered sanitation (organic waste, anthropogenic in origin) could also cause As toxicity in rural Bengal. In the agricultural lands, higher mean values of alkalinity, phosphate, sulphate, hardness and electrical conductivity was observed, and could be linked with the excessive use of fertilizers for agricultural production. Bio-markers study indicates that the accumulation of As in hair and nail is related with the construction of exposure scenario with time dimension. The strength and weakness of the on-going West Bengal and Bangladesh drinking water supply scenario and achievability towards alternative options are also evaluated.