DDT and HCH (Organochlorine Pesticides) in Residential Soils and Health Assessment for Human Populations in Korba,India

Dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), and their isomers’ levels in residential soils were determined for the assessment of health risk in Korba, India. Observed concentrations of total HCH and total DDT in soils were more or less comparable with other parts of India and the world. ΣHCH and ΣDDT concentrations ranged between 0.9–20 μg kg^?1 and 2–315 μg kg^?1, respectively, which were lower than recommended soil quality guidelines indicating low ecotoxicological risk. Carcinogenic and non-carcinogenic impacts of HCH and DDT on human populations through soil ingestion were evaluated and presented. The incremental lifetime cancer risk (ILCR) for adults and children ranged between 7.8 × 10^?10–1.6 × 10^?7 and 4.1 × 10^?9–8.2 × 10^?7, respectively. Non-cancer health hazard quotient (HQ) ranged between 5.9 × 10^?7–1.8 × 10^?3 and 3.1 × 10^?6–9.4 × 10^?3, respectively, for adults and children. The estimated ILCR and HQ were within the safe acceptable limits of 10^?6–10^?4 and ≤1.0, respectively, indicating low risk to human populations from exposure to organochlorine pesticides (HCH and DDT) in the study area.     

Risk Assessment of Aflatoxin B1 from Food Consumption in the Korean General Population

Levels were evaluated of Aflatoxin B₁ (AFB1) exposure through the intake of AFB1-contaminated foods among Koreans. Average daily intake, excess cancer risk, and population risk of AFB1 from food intake were calculated from Koreans with age greater than 20 years. Average daily intake of AFB1 by food ingestion was 0.064 ～ 0.361 ng/kg bw/ day. Excess cancer risk of AFB1 in food with the surface antigen of the hepatitis B-virus negative (HBsAg^?) and positive (HBsAg⁺) population was 5.76 × 10^{? 7}～ 3.25 × 10^{? 6} and 1.47 × 10^{? 5}～ 8.31 × 10^{? 5}, respectively. Application of JECFA's two tentative maximum levels (MLs) (10 μ g/kg and 20 μ g/kg) resulted in the population risk of 0.0009 ～ 0.0075 and 0.0014 ～ 0.0079 cancers/year/100,000 people, respectively, indicating that lower ML does not give a significant reduction of the risk. However, because Korea has a high incidence of HBsAg⁺ individuals, adoption of lower ML may be a reasonable decision to protect a high risk group. This is the first report on the risk assessment of AFB1 in food among the Korean population. Our study will contribute to providing the solid basis of establishing the maximum levels of AFB1 exposure through food ingestion in Korea as well as other countries.     

Quantitative Risk Assessment of Trichloroethylene for a Former Chemical Works in Shanghai,China

Assessment of the potential risks posed by chlorinated solvents in groundwater is the key to establish the extent of the contamination and derive achievable remedial targets should remediation deems necessary. This article first presents the application of the American Society for Testing and Materials (ASTM) Risk Based Corrective Actions (RBCA) Guidance to quantitatively evaluate human health and environmental risk for a former chemical works in Shanghai, China. The observed maximum trichloroethylene (TCE) concentration in groundwater at the site reached 1220 mg/l that exceeded its solubility of 1070 mg/l at 10°C (Soil annual average temperature is 10°C in Shanghai). The maximum concentration for cis-1, 2-DCE (DCE) was also found to be elevated at 264 mg/l. A critical exposure pathway was considered to be indoor vapor intrusion of TCE into the buildings with excess lifetime cancer risk for children being 1.7 × 10^?3. This cancer risk exceeded regulatory limits of 1 × 10^?4 to 1 × 10^?6 for The Netherlands, the United Kingdom, and the United States. The calculated groundwater remedial targets for TCE and DCE are 7 mg/l and 904 mg/l, respectively, in order to protect child residents from inhalation of indoor vapors within the close proximity of the source area.     

Implications of Using Steady-State Conditions in Estimating Dermal Uptake of Volatile Compounds in Municipal Drinking Water: An Example of THMs

Dermal exposure to volatile compounds (VC) in municipal water while showering is typically estimated using a steady-state condition between VC in water impacting on skin and skin exposed to water. The lag times to achieve steady-state between VC and skin can vary in the range of 7.5–218.3 min, while shower duration is often less than these values. Estimates of dermal exposure to VC using steady-state while showering may misinterpret exposure. This study developed models and estimated exposure to some disinfection byproducts (DBPs) through dermal pathway by considering lag times while showering. Dermal uptakes of VC were compared using different approaches. In the proposed approach, uptakes of trihalomethanes were estimated between 9.55 × 10^?10–1.43 × 10^?8 mg/cm² of skin during the lag times from exposure to water with trihalomethanes of 50 μg/L. These values were higher than the steady-state estimates (1.37 × 10^?10–4.34 × 10^?9 mg/cm²), and lower than the average exposure analysis (4.12 × 10^-8–1.93 × 10^?6 mg/cm²). Using the Drinking Water Surveillance Program data in Ontario, chronic daily intakes of trihalomethanes were estimated to be 9.40 × 10^?7 (1.85 × 10^?7–1.65 × 10^?6), 3.89 × 10^?6 (7.11 × 10^?7–2.33 × 10^?5), and 1.40 × 10^?6 (4.0 × 10^?7–1.77 × 10^?6) mg/kg/day in Toronto, Ottawa, and Hamilton, respectively. The findings can be useful in understanding THMs exposure and risk through dermal pathway.     

Risk Assessment for Natural Uranium in Subsurface Water of Punjab State,India

Traces of uranium were measured by laser fluorimeter in 235 subsurface water samples collected from four districts of Punjab state in India. The concentration of U in water samples ranged between <2–644 μg/L with a mean value of 73.1 μg/L. The radiological risk was observed to be in the range of 5.55 × 10^?6–1.78 × 10^?3 with a mean value of 2.03 × 10^?4, which is around 22% more than the maximum acceptable level (l.67 × 10^?4) as per guidelines of India's Atomic Energy Regulatory Board. The mean of chemical toxicity risk, expressed as life time average daily dose (LADD) was worked out to be 5.56 μg/kg/day with a range of 0.15–48 μg/kg/day by considering a bodyweight of 51.5 ± 8.5 kg, water ingestion rate of 4.05 L/d, and life expectancy of 63.7 yrs for an adult Indian reference man and compared with the reference dose (4.53 μg/kg/day). The average exposure level of U was comparatively high and the chemical toxicity was expected to be more. The mean of hazard quotient (LADD/ RfD) for all four districts was found to be greater than 1, indicating that groundwater may not be suitable for consumption from a chemical toxicity point of view.     

Human health risk from exposure to metals through fish and shellfish ingestion in Saudi Arabia

Abstract

In this study, human exposure and risks of metals through fish ingestion were predicted. Concentrations of 10 metals (Cd, As, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in 17 commonly eaten fish species in Saudi Arabia were characterized. Using the fish ingestion patterns, chronic daily intakes of metals among the Saudi and expatriate populations were predicted to be in the ranges of 8.89?×?10^?06–1.08?×?10^?02 and 6.59?×?10^?06–7.97?×?10^?03?mg/kg/day, respectively. The average cancer risks from inorganic arsenic were 2.76?×?10^?05 and 2.09?×?10^?05 for Saudi and expatriate, and the ranges were 1.61?×?10^?09–1.58?×?10^?03 and 2.64?×?10^?09–1.27?×?10^?03, respectively. The predicted risks were much lower than the previously reported risks. There were 47.4% and 42.4% chances that cancer risks would be higher than 1.0?×?10^?05 (10 per million) among Saudi and expatriate, respectively. The average cumulative hazard index (HI) for Saudi and expatriate were 0.324 and 0.239 with the ranges of 0.0142–7.26 and 0.017–6.43, respectively. Approximately 3.06% and 1.56% cases among Saudi and expatriate had HI greater than unity, indicating possible health concern, respectively. Through comprehensive understanding of exposure and risks, strategies can be adopted to protect human health.     

A quantitative risk ranking model to evaluate emerging organic contaminants in biosolid amended land and potential transport to drinking water

A quantitative risk ranking model was developed for human exposure to emerging contaminants (EC) following treated municipal sewage sludge (“biosolids”) application to Irish agricultural land. The model encompasses the predicted environmental concentration (PEC) in soil, surface runoff, groundwater, and subsequent drinking water ingestion by humans. Human exposure and subsequent risk was estimated for 16 organic contaminants using a Monte Carlo simulation approach. Nonylphenols ranked the highest across three environmental compartments: concentration in soil (PEC_soil), runoff (PEC_runoff), and groundwater (PEC_groundwater), which had mean values of 5.69 mg/kg, 1.15 × 10^?2 µg/l, and 2.22 × 10^?1 µg/l, respectively. Human health risk was estimated using the LC₅₀ (chemical intake toxicity ratio, (RR)) as a toxicity endpoint combined with PEC_runoff and PEC_groundwater. NP ranked highest for LC₅₀ combined with PEC_runoff and PEC_groundwater (mean RR values 1.10 × 10^?4 and 2.40 × 10^?3, respectively). The model highlighted triclocarban and triclosan as ECs requiring further investigation. A sensitivity analysis revealed that soil sorption coefficient and soil organic carbon were the most important parameters that affected model variance (correlation coefficient –0.89 and –0.30, respectively), highlighting the significance of contaminant and soil properties in influencing risk assessments. This model can help to prioritize emerging contaminants of concern requiring vigilance in environmental compartments.     

Environmental and Human Health Risk Assessment of Benzo(a)pyrene Levels in Agricultural Soils from the National Capital Region,Delhi, India

ABSTRACT

Exposure to benzo(a)pyrene (B(a)P) for health risk was studied in soils from the Delhi region, India. The mean and median concentrations of benzo(a)pyrene were 0.031 and 0.029 (±0.002) mg/kg, respectively. The lifetime average daily dose (LADD) for adults and children was 1.7 × 10^?8 mg kg^?1 d^?1 and 7.5 × 10^?8 mg kg^?1 d^?1, respectively, with incremental life time cancer risk (ILCR) of 1.2 × 10^?7 and 5.5 × 10^?7, respectively. The Index of Additive Cancer Risk (IACR) was 0.084. Our screening-level risk assessment shows that the observed ILCR and IACR values are much lower than the guideline values of 10^?6 ? 10^?4 (ILCR) and <1 (IACR), respectively, and therefore the measured B(a)P levels in soil may not portend environmental and human health risks.     

Distribution,sources, and health risk assessment of polycyclic aromatic hydrocarbons in dust from urban environment in the Niger Delta,Nigeria

The concentrations of the 16 U.S. Environmental Protection Agency polycyclic aromatic hydrocarbons (PAHs) were measured in urban street dust with a view to understanding the potential risk to urban residents exposed to street dust, sources, and distribution of the PAHs. Gas chromatography–mass spectrometry was used to measure the concentrations of the PAHs after ultra-sonication with hexane/dichloromethane and clean up. The total concentrations of the ?16 PAHs in the urban street dust from Warri and its environs ranged from 165.1 to 1012 µg kg^?1. The isomeric ratios and the PCA indicated that combustion of petroleum and biomass are the major sources of PAHs in Warri and its environs. The total BaP carcinogenic and mutagenic potency concentrations (?BaP_TEQ and ?BaP_MEQ) were in the range of 0.03 to 219 µg kg^?1 and 0.52 to 182 µg kg^?1, respectively. The incremental life cancer risk from exposure of the residents of Warri and its environs ranged from 4.07 × 10^?7 to 3.11 × 10^?3 and 2.13 × 10^?7 to 1.49 × 10^?3 for the children and adults, respectively, which were higher than the baseline value of acceptable risk of 10^?6 (i.e., one case per million people).     

Trihalomethanes in desalinated water: Human exposure and risk analysis

Desalinated seawater is used to satisfy domestic water demands in many countries. The treated freshwater is blended with desalinated water to increase the water supply. The desalinated and blended water contains disinfection byproducts (DBPs), some of which may induce cancer risk to human. In this study, concentrations of trihalomethanes (THMs) in desalinated and blended water in Saudi Arabia were investigated, and human exposure and risk were predicted. The intakes of THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) were predicted to be 8.38 × 10^?5, 7.57 × 10^?5, 2.54 × 10^?5, and 4.32 × 10^?4 mg/kg-d, respectively. The overall cancer risk and hazard index were estimated to be 1.78 × 10^?5 (range: 7.40 × 10^?7–9.26 × 10^?5) and 3.49 × 10^?2 (range: 1.20 × 10^?3–2.34 × 10^?1), respectively. The probabilities of cancer risk exceeding the risk levels of 1 × 10^?6, 1 × 10^?5, and 5.0 × 10^?5 were 1.0, 0.775, and 0.012, respectively. The loss of disability adjusted life years (DALYs) was predicted to be 25.1 per year while the cancer risk represented 8.48 × 10^?7 DALY per person per year. The financial burden from such risk was estimated to be US$ 2.72 (range: US$ 2.52–2.91) million per year. The findings may assist in better understanding and reducing cancer risk from DBPs in desalinated and blended water.     

The influence of hexavalent chromium salt on the population growth,cell morphology,and physiological parameters of the benthic microalga <Emphasis Type="Italic">Attheya ussurensis</Emphasis> Stonik,Orlova, Crawford, 2006 (BACILLARIOPHYTA) in culture

The presence of hexavalent chromium salt in culture medium negatively affected the growth dynamics and physiological parameters of the benthic microalga Attheya ussurensis. After 1 day of exposure to toxicant at concentrations of 2, 4, 7, and 10 mg/l, the cell counts were 10, 7.9, 5.6, and 4.3 × 10³ cells/ml, respectively (versus 13 × 10³ cells/ml in the control). A tendency towards a decrease in cell number remained until the end of the experiments; after 7 days of exposure the cell counts were 133, 102, 11, and 7.5 × 10³ cells/ml (versus 204 × 10³ cells/ml in the control). With increase in potassium bichromate concentration in the culture medium, there was an increase in the ratio of cell height to width and a change in the form of the cell to horseshoe shaped. The contents of chlorophyll a in microalgal cells after 1 day of exposure to 2, 4, 7, and 10 mg/l were 40, 37, 34, and 30 μg/l, respectively (45 μg/l in the control). After 7 days, at chromium salt concentrations of 2 and 4 mg/l, the chlorophyll a content was higher (670 and 647 μg/l) than in the control (605 μg/l); at 7 and 10 mg/l, it significantly decreased to 87 and 65 μg/l, respectively. The contents of carotinoids in microalgal cells after 7 days of exposure to 2 and 4 mg/l were comparable to the control values, while at 7 and 10 mg/l they decreased sharply. The amount of phaeophytin (as a percentage of total chlorophyll a content) increased with increasing potassium bichromate concentration.     

Using the RESRAD Code to Assess Human Exposure Risk to 226Ra, 232Th,and 40K in Soil

This article evaluates the health risk raised by exposure to naturally occurring radionuclides in soil around Khak-Sefid, Ramsar, Iran, which is an area of high natural background radiation. A high purity germanium detector was used to determine levels of radionuclides in soil samples and the cancer morbidity risk for a hypothetical resident farmer was evaluated using the RESidual RADioactivity (RESRAD) code. The average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 13,201 ± 391, 27.9 ± 2.4, and 415.5 ± 16 Bq/kg, respectively. The maximum assessed cancer morbidity risks were calculated from external and internal exposure pathways as 4.73 × 10^?2 and 3.40 × 10^?2 for ²²⁶Ra, 1.41 × 10^?4 and 7.88 × 10^?5 for ²³²Th, and 1.3 × 10^?4 and 4.233 × 10^?4 for ⁴⁰K. The RESRAD calculations also showed total cancer morbidity risks from external gamma and plant ingestion pathways were more important than from other exposure pathways. A sensitivity analysis was also performed to determine the input parameter values in the risk assessment process. In general, due to the high calculated risk of ²²⁶Ra compared with ²³²Th and ⁴⁰K it can be the major source of concern for human heath in the study area.     

Toxicity of Chemically Spiked Sediment to the Carpet Shell Clam Ruditapes decussatus Embryos and Larvae

The objective of this research was to assess the toxicity of sediment contaminated with cadmium, DDT, chlorpyrifos, and fluoranthene to embryos and larvae of the European clam Ruditapes decussatus, exposed to two sediment fractions, the whole sediment and elutriate. The percentages of abnormal D-shaped larvae and larval mortality have been investigated. The median effective concentration (EC50) values, reducing 50% of the percentage of D-shaped larvae, in whole sediments and elutriates were, respectively, 1.17 mg/kg and 417.1 μgl^?1 (3.71 μM) for cadmium, 1.66 mg/kg and 97.8 μgl^?1 (0.48 μM) for fluoranthene, 1.71 mg/kg and 384.8 μgl^?1 (1.08 μM) for DDT, and 0.96 mg/kg and 339.5 μgl^?1 (0.96 μM) for chlorpyrifos. The 96h-median lethal concentrations (LC50) reducing larval survival by 50% were 4.04 mg/kg 654.3 μgl^?1 (5.82 μM) for cadmium, 17.41 mg/kg 8666.6 μgl^?1 (42.84 μM) for fluoranthene, 3.93 mg/kg and 457.4 μgl^?1 (1.29 μM) for DDT, and 2.53 mg/kg and 308.06 μgl^?1 (0.87 μM) for chlorpyrifos. Based on EC₅₀ and LC₅₀ comparisons to toxicity data for other marine species, these findings suggest that the R. decussatus embryotoxicity and larvae mortality bioassay were among the most sensitive tools for sediment quality assessment.     

Evaluation of PAHs concentration and cancer risk assessment on human health in a roadside soil: A case study

Abstract

An explanatory study was carried out to divulge the sources, contamination level of different classes of Polycyclic Aromatic Hydrocarbons (PAHs) distribution and the impact of vehicular traffic on the roadside soil by assessing incremental lifetime cancer risk at each site to understand the potential health risk of nearby residents along the National Highway-2 Delhi–Kolkata India. Comparison of the cancer risk assessment was performed using Monte Carlo simulation for the entire study area. The results revealed 90% cancer risk value of 6.40?×?10^?5 and 6.5?×?10^?5 for children and adults, respectively, whereas, without simulation the Total Cancer Risk (TCR) for adults was 6.925?×?10^?5 and 6.220?×?10^?5 for children, observed maximum at the location (S5). The dilemma of risk assessment indicating profoundly contaminated soil. Comparison of PAHs concentration with the background values of PAHs ranged from 1.478 to 27.493?mg kg^?1. The (IP/BgP) ratio specified that the PAHs content of the highway roadside sample is preponderate by diesel vehicle emission, biomass combustion and coal combustion. The study clearly revealed and advocated the influence of organic and inorganic pollution, which aggravates and causes health issues to the nearby inhabitants. This study could also be advantageous to similar consequences seen elsewhere in the world.     

Effect of Plant Growth Regulators on Phytoremediation of Hexachlorocyclohexane-Contaminated Soil

The influence of three plant growth regulators, indolebutyric acid (IBA), thidiazuron (TDZ) and gibberellic acid (GA₃), either individually or in pair-wise combinations, on the ability of waxy corn plant to remove hexachlorocyclohexane (HCH) from contaminated soil was studied. Waxy corn seeds were immersed for 3 h in solutions of 1.0 mg/l IBA, 0.01 mg/l TDZ, 0.1 mg/l GA₃, or a mixture of two of the growth regulators, and then inoculated in soil contaminated with 46.8 mg/kg HCH for 30 days. Pretreatment of corn seeds with the plant growth regulators did not enhance corn growth when compared with those immersed in distilled water (control), but the pretreatment enhanced HCH removal significantly. On day 30, HCH concentration in the bulk soil planted with corn seeds pretreated with GA₃ or TDZ+GA₃ decreased by 97.4% and 98.4%, respectively. In comparison, HCH removal in soil planted with non-pretreated control waxy corn seeds was only 35.7%. The effect of several growth regulator application methods was tested with 0.01 mg/l TDZ. The results showed that none of the methods, which ranged from seed immersion, watering in soil, or spraying on shoots, affected HCH removal from soil. However, the method of applying the growth regulators may affect corn growth. Watering the corn plant with TDZ in soil led to higher root fresh weight (2.2 g) and higher root dried weight (0.57 g) than the other treatments (0.2–1.7 g root fresh weight and 0.02–0.43 g root dried weight) on day 30. Varying the concentrations of GA₃ did not affect the enhancement of corn growth and HCH removal on day 30. The results showed that plant growth regulators may have potential for use to enhance HCH phytoremediation.     

Effect of pressure on the sol-gel transition of carrageenans

The effects of pressure on the sol-gel transition of κ- and ι-carrageenans were studied in KCl solutions under high pressures up to 3000 kg/cm². The carrageenan gels were destabilized by pressure: the pressure depression of melting temperature, (dT/dP)_m, was ?5.7 × 10^?3 and ?4.0 × 10^?3 K cm²/kg independent of KCl concentration for κ- and ι-carrageenans, respectively. The enthalpy, entropy and volume changes accompanying the gel formation were calculated from the Eldridge-Ferry's plots and the Clausius-Clapeyron equation. The volume change per unit cross-link (two disaccharide residues) was estimated to be (2.5 ～ 4.9) and (1.7 ～ 3.4) ml/mol for κ- and ι-carrageenans, respectively. The compressibility of both carrageenan molecules appeared to be larger by (1.6 ～ 2.6) × 10^?12 (κ-form) and by (0.8 ～ 1.3) × 10^?12cm²/dyn (i-form) in gel state as compared with in sol state These increases in volume and compressibility on gelation were attributed to a reduction of water of hydration from the carrageenan molecules, which is mainly due to a replacement of the polymer-water hydrogen bond by the polymer-polymer hydrogen bond. These results seemed not inconsistent with the idea that a double helix structure of carrageenan gels may persist in solution as well as in the solid state.     

Estimation of Excess Cancer Risk on Time-Weighted Lifetime Average Daily Intake of PAHs from Food Ingestion

The purposes of this study were to quantify the time-weighted, lifetime average, daily intake (LADI) of polycyclic aromatic hydrocarbons (PAHs) through food ingestion and to estimate the excess cancer risk based on lifetime dietary PAH intake. Twenty-seven different food commodities were selected from the 2001 Korean National Health and Nutrition survey based on their frequent consumption and high PAH level. The foods were analyzed for the profile of 14 PAH congeners using high performance liquid chromatography (HPLC) and fluorescence detector. Considering the toxic equivalent (TEQ) level converted with the toxic equivalent factors (TEFs), the highest total TEQ level of PAHs in foods was detected from roasted laver at 1.2 ug TEQ/kg. For the PAH exposure assessment according to ingested foods, the average body weight was separated according to the following age groups, 1–6, 7–19, 20–64 and over 64 years, and the daily food ingestion rates from the National Health and Nutrition survey were used. The estimated Lifetime Average Daily Intake (LADI) of PAHs was 3.22 × 10^–3 ug/kg/day for carcinogenic effects and was higher in the younger age groups under 20 years old than in the older groups. The dietary excess cancer risk estimated using the cancer potency of benzo(a)pyrene (7.3(mg/kg/day)^?1) was 2.3 × 10^?5, which is equivalent to a probability of tumor eruption in the upper gastrointestinal tract of two per hundred thousand persons.     

Quantification of nitrophenols,chlorophenols, and hexachlorocyclohexanes in agricultural soils in the vicinity of industrial area for the assessment of human health hazard and risk

In this study, quantification of nitrophenol (NP), chlorophenol (CP), and hexachlorocyclohexane (HCH) compounds in agricultural soils in the vicinity of the industrial region in northern Uttar Pradesh, India was carried out for the assessment of human health hazard. The concentration of ∑NP, ∑CP, and ∑HCH compounds ranged 0.33–3.64 mg kg^?1, 0.06–3.18 μg kg^?1, and 1.23–17.24 mg kg^?1, respectively, and were within the soil quality guidelines for the protection of human and environment health. Human health hazard index and cancer risk, on the basis of average daily intake of these compounds through soil for human adults and children, was lower than the acceptable limit. This study suggested low health hazard and risk due to phenolic and HCH compounds to human population.     

The Health and Ecological Impacts of Organochlorine Pesticide Pollution in China: Bioaccumulation of Organochlorine Pesticides in Human and Fish Fats

The levels of organochlorine pesticides (OCPs) in the environment and foods have declined significantly in China since 1983, the year when their use in agriculture was officially banned. The levels today of these contaminants in soil, water, and agricultural products are well below 50 μg/kg in many parts of China. Yet in spite of such a decline, the current levels of pollution still pose a significant health risk to many people in China because OCPs are highly persistent and bioaccumulative substances. This preliminary study was conducted to monitor the levels of hexachlorocyclohexane (HCH) and dichloro-diphenyl-trichloroethane (DDT) in human and fish fats from southeast China in an effort to corroborate the above health concern. The data reconfirmed that pollution by HCH and DDT, which are the major components of OCPs, is a serious ecological problem in the study region, and likely in other parts of China as well. The HCH contents in the human samples were between 0.25 and 2.20 mg/kg, with an average of 0.90 mg/kg. The DDT contents in these human samples were much higher, between 0.54 and 9.22 mg/kg with an average of 3.50 mg/kg. The major isomers found in the human samples were β-HCH and p, p′-DDE, representing 94.9 to 99.5% of total HCH and 72.3 to 96.7% of total DDT, respectively. The HCH and DDT content in the grass carp samples averaged 0.03 and 0.67 mg/kg, respectively. The levels of bioaccumulation reflected in these human and fish samples were considered substantial, particularly when residents in the study region continue to be exposed to the OCPs remaining so persistently in their environment. It is therefore important for the health authorities to launch a large-scale investigation into the potential health and ecological impacts of OCP pollution in China. The data also suggested that the current national standards might need to be lowered for the levels of OCPs in the environment in China.     

Health risks of heavy metals to the general public in Hengyang,China, via consumption of rice

This investigation was conducted to survey the levels of cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), and manganese (Mn) in polished rice collected at supermarkets located in Hengyang, China. The surveyed rice samples were grouped according to their production areas into four different groups—Hunan, Jiangxi, Jilin, and Thailand. The data showed that the highest means of Cd, Pb, Cr, Cu, Zn, and Mn contents were in rice samples produced from Hunan (0.215 mg/kg), Thailand (0.537 mg/kg), Hunan (0.348 mg/kg), Jiangxi (2.472 mg/kg), Thailand (17.259 mg/kg), and Jinlin (9.326 mg/kg), respectively. Average daily intake dose for the six elements through consumption of rice was lower than the oral reference dose. Although the hazard quotient values for all six elements were <1.0, hazard index values in all the production areas (except Thailand) were >1.0, and cancer risk (CR) and total CR values were >10^?4, respectively. Certainly, there are inherent limitations for these health risk values, including actual ingestion rate, exposure duration, and bioavailability of heavy metals. These results indicate that long-term heavy metal exposure by consumption of rice in Hengyang could pose both potential non-carcinogenic and carcinogenic health risks to the local residents.