An Assessment of Ingestion Dose due to the Intake of ^210Po and ^210Pb through Drinking Water of Eloor, Ernakulam District, Kerala, India

The present study aims at measuring the activity concentrations of ^210Po and ^210Pb in the potable water of Eloor, a major industrial belt in the Ernakulam district of Kerala, India with an aim of evaluating resultant ingestion dose to critical population. The industrial units located in Eloor discharge their treated effluents into the river Periyar and the surrounding environs. The two major industries of interest with respect to NORMs are the fertilizer plant, processing rock phosphate and the monazite processing plant, which had been in operation for the last 50 years. For sampling, Eloor region was divided into four zones and a total of 55 water samples from different locations were collected and analysed as per standard analytical procedure manual of BARC. The ^210Po concentration ranged between 0.3 to 4.7 mBq.L^-1 and ^210Pb ranged from 0.6 to 4.3 mBq.L^-1. All values are well below the limit of 0.1 Bq.Ll recommended by World Health Organization. Statistical analysis shows a good co-relation between ^210Po and ^210Pb in the water samples analyzed and the mean activity concentration is found to be relatively high in the western region of Eloor compared to other regions. The annual effective dose equivalent to man from ^210Po and ^210Pb through drinking water intake were estimated and found to be 1.13 μSv.y^-1 and 0.99 μSv.y^-1 respectively, which is well below the reference level of committed effective dose （100 μSv.y^-1） recommended by WHO.

Differences on Pb accumulation among plant tissues of 25 varieties of maize(Zea mays)

Pollution of agricultural land by heavy metals has imposed an increasingly serious risk to environmental and human health in recent years.Heavy metal pollutants may enter the human food chain through agricultural products and groundwater from the polluted soils.Progress has been made in the past decade on phytoremediation,a safe and inexpen-sive approach to remove contaminants from soil and water using plants.However,in most cases,agricultural land in China cannot afford to grow phytoremediator plants instead of growing crops due to food supply for the great population.Therefore,new and effective methods to decrease the risk of heavy metal pollution in crops and to clean the contaminated soils are urgently needed.If we can find crop germplasms(including species and varieties)that accumulate heavy metals in their edible parts,such as the leaves of vegetables or grains of cereals,at a level low enough for safe consumption,then we can grow these selected species or varieties in the lands contaminated or potentially contaminated by heavy metals.If we can find crop germplasms that take in low con-centrations of heavy metals in their edible parts and high con-tent of the metals in their inedible parts,then we can use these selected species or varieties for soil remediation.In this study,the feasibility of the method is assessed by analyzing Pb concentrations in edible and inedible parts of 25 varieties of maize(Zea mays)grown in Pb-contaminated soils.The soil concentrations of Pb were 595.55 mg/kg in the high Pb exposed treatment and 195.55 mg/kg in the control.The results showed that the Pb concentrations in different tissues were in the order of root>shoot≌leaf>grain.Com-pared with the control,the Pb concentrations in root,shoot and leaf were greatly increased under the high Pb exposed condition,while the increments of Pb concentration in grain were relatively lower.Under the high Pb exposure,the grain Pb concentrations of 12 varieties exceeded the maximal Pb limitation of the National Food Hygiene Standard of China(NFHSC)and were inedible.This indicates that there is a high Pb pollution risk for maize grown on Pb polluted sites.Although 22 of the 25 tested varieties had harvest loss under the highly Pb stressed condition,ranging from 0.86%-38.7%of the grain biomass acquired at the control,the average harvest loss of all the tested varieties was only 12.6%,which is usually imperceptible in normal farming practices.There-fore the risk of Pb pollution in maize products cannot be promptly noticed and prevented based only on the outcome of the harvest.However,we did find that 13 of the 25 tested varieties had grain Pb concentrations lower than the limita-tion of the NFHSC.It is,therefore,possible to reduce the pollution risk if these favorable varieties are used for maize production in Pb-contaminated or potentially contaminated agricultural lands.Pb concentrations in vegetative tissues(root,stem and leaf)were significantly correlated with each other,while Pb concentrations of each vegetative tissue were not significant-ly correlated with that of grain.Among the 25 tested varieties,some varieties had Pb concentrations in grain lower than(No.1-3 and No.6)or slightly above(No.4)the limitation of the NFHSC,while their Pb concentrations in the vegetative tissues were among the highest.When excluding these variet-ies,correlations between the Pb concentrations of grain and those of vegetative tissues of the rest of the tested varieties became highly significant.In addition,variety No.1 had the lowest harvest loss under high Pb exposed,and the highest Pb accumulation in vegetative tissues(51.69 mg/plant,12 times as much as in the control).Similar features were also observed in varieties No.2,No.3 and No.6,which absorbed Pb for 36-42 mg/plant under high Pb exposed.We recommend these varieties of maize to be used for bioremediation of Pb contaminated soil and crop production at the same time.

Initial results for urban metal distributions in house dusts of Syracuse,New York,USA

A program of house dust sample collection and analysis has begun in Syracuse,New York,USA,in order to determine the feasibility of a geography-based exposure assessment for urban metals.The sampling program,and the protocols it employs,is described for two different types of wipe media,Ghost Wipes and Whatman Filters.Preliminary results show that strong spatial patterns of floor dust loading(mg dust per square foot)can be observed for data aggregated at a spatial scale of about 1600 m(~2.5 km^(2)).Floor dust metal concentrations were similar to those found in other urban environments,with some regional variation.The median floor dust Pb concentration was~108 mg·kg^(-1)for this initial data set of~264 sampled residential locations,and varied from 50 to 1100 mg Pb·kg^(-1).