A Preliminary Human Health Risk Assessment of Organochlorine Pesticide Residues Associated with Aquatic Organisms from the Rangsit Agricultural Area,Central Thailand

Food consumption is one of the main routes of human exposure to organochlorine pesticide residues (OCPRs). To assess the potential health risks associated with OCPRs contaminants due to freshwater organism consumption, a number of vegetables, prawn, snail, and fish were collected from Khlong 7 (canal), Rangsit agricultural area, Pathum-Thani Province, Thailand. The samples were extracted using a multiresidue extraction method and then analyzed by gas chromatography with microelectron capture detector (μ -ECD). The results show that low concentrations of OCPRs were detected in parts per billion (ppb) levels. Based on a plausible worst-case scenario, the local population could be at risk for cancer due to consumption of fish contaminated by α -, β -HCH, heptachlor, heptachlor epoxide, aldrin, dieldrin, DDD, DDE, and DDT. Likewise, individuals may be at risk from consumption of Lanchester's freshwater prawn Macrobrachium lanchesteri, freshwater snail Filopaludina mertensi, swamp morning-glory Ipomomea aquatica, neptunia Neptunia oleracea, and water lily Nymphaea lotus because these species all contained elevated concentrations of α -, β -HCH, heptachlor, heptachlor epoxide, aldrin, and dieldrin.     

Ecological Risk Assessment of Organochlorine Pesticides in Surface Waters of Lake Taihu,China

The residues of organochlorine pesticides (OCPs) in surface waters from Meiliang Bay, Gonghu Bay, and Xukou Bay of Lake Taihu, China, were investigated, and their ecological risks were assessed using the risk quotient method and probabilistic risk assessment. Environmental concentrations of OCPs in surface water of these bays were relatively lower compared with other rivers or lakes in China. Calculation of risk quotient associated with taxonomic groups indicates moderate ecological risks from OCPs for crustaceans and insects in these bays, while the ecological risks were low for fish and negligible for phytoplankton. The ecological risk quotients associated with individual OCPs were lower than 0.01 in these bays, suggesting a negligible risk to aquatic organisms. Ecological risk from α-HCH was relatively lower compared with DDTs, endosulfans, and γ-HCH. The combined ecological risks were evaluated using probabilistic risk assessment for only eight OCPs owing to a lack of available toxicity data for β-HCH and δ-HCH. The percentage of species with the potential to be at risk from mixture of OCPs was lower than the criteria of 5% in each bay, indicating that the combined ecological risks were acceptable.     

Potential Dermal Exposure and Risk Assessment for Applicators of Chlorothalonil and Chlorpyrifos in Cucumber Greenhouses in China

Occupational exposure to pesticides has not been conducted in depth so far in China. The potential dermal exposure and risk assessment were conducted for applicators through application with a knapsack power sprayer in cucumber greenhouses. The spray suspension was prepared with 75% chlorothalonil WP and 48% chlorpyrifos EC. The dermal patch method was applied to assess the potential dermal exposure (PDE) of applicators during application. The average total PDE on the whole body of applicators during application of chlorothalonil and chlorpyrifos was 83.2 mL h^?1 and 85.1 mL h^?1, respectively. The most exposed part of the body was arms, especially the right arm. For risk assessment, the margin of safety (MOS) was calculated from the PDE. The MOS values were 0.1 and 0.2 for application of chlorothalonil and chlorpyrifos, respectively, both less than 1, which indicated low possibility of health risk.     

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 Perception and Chronic Exposure to Organochlorine Pesticides in Maya Communities of Mexico

In order to analyze risk perception related to the use and handling of organochlorine pesticides (OCP) in agricultural and livestock activities among Maya communities of Yucatan, Mexico, and to study their impact on public health and the environment, we conducted an analytical study applying 274 semi-structured interviews in 11 municipalities in the zone called “Ring of Cenotes.” The harmful effects of agrochemicals on water supplies, soils, air, and human health were considered, including the indoor use of pesticides to preserve harvest products. Recent studies showed high levels of OCP in groundwater. A generalized low risk perception related to human health and the environment due to pesticide use was found. Likewise, social parameters were analyzed, including the educational level, as well as risk factors related to groundwater karst vulnerability. Pesticides that have been banned by international conventions are still in use. The occurrence of some diseases such as cervical cancer, with a very high prevalence at the national level, and the practice of obtaining drinking water from polluted wells and sinkholes, may be associated with this low risk perception and with poor social conditions. Establishing programs on health education, agro-ecological production alternatives, and water chemical quality monitoring is recommended.     

Organophosphate Pesticide Residues in Drinking Water from Artesian Wells and Health Risk Assessment of Agricultural Communities,Thailand

Organophosphate pesticide (OPPs) concentrations in artesian wells located in Thai agricultural and non-agricultural communities were studied during both wet and dry seasons. A total of 100 water samples were collected and subjects were asked to complete a survey. Gas chromatography flame photometric detector was used for OPP analysis. The average OPP concentration in the agricultural communities (0.085 and 0.418 μg/l in dry and wet season) was higher than in the non-agricultural communities (0.004 μg/l in both seasons). Ingestion of OPPs in contaminated water in the agricultural communities were estimated to be 0.187 and 0.919 μg/day during the dry and wet seasons, respectively, and 0.008 μg/day during both seasons in the non-agricultural communities. Agricultural communities were exposed to pesticide residues under the oral chronic reference dose. This study suggests that people in agricultural communities may be exposed to significantly greater levels of pesticides than non-agricultural populations during the dry and wet seasons (p < .001, .001).     

Approaches for Integrated Risk Assessment

Recognizing the need to enhance the effectiveness and efficiency of risk assessments globally, the World Health Organization's International Programme on Chemical Safety, the U.S. Environmental Protection Agency, the European Commission, and the Organization for Economic Cooperation and Development developed a collaborative partnership to foster integration of assessment approaches used to evaluate human health and ecological risks. The objectives of this effort included: improving understanding of the benefits of integration, identifying obstacles to the integration process, and engaging key agencies, organizations, and scientific societies to promote integration. A framework with supporting documentation was developed to describe an approach for integration. Four case studies were constructed to illustrate how integrated risk assessments might be conducted for chemical and nonchemical stressors. The concepts and approaches developed in the project were evaluated in an international workshop. The goal of this effort was international acceptance of guidance for integrated risk assessment.     

Inter- and Intra-Species Extrapolation in Risk Assessment of Different Classes of Pesticides

Risk assessors routinely use the reference dose (RfD) approach for non-cancer risk assessment. In this approach, No-Observed-Adverse-Effect-Level (NOAEL) is divided by the product of uncertainty factors (UFs) and, occasionally, an additional modifying factor (MF), each usually employed by default as factors of 10. In the present investigation, kinetic and dynamic data have been used in order to reduce uncertainties when establishing exposure guidelines for examples of chemicals representing four classes of pesticides (warfarin, lindane, carbaryl and parathion). An intensive search of databases was conducted for these pesticides, and toxicokinetic and toxicodynamic parameters in inter- and intra-species were evaluated. The kinetic and dynamic subfactors were less than the proposed values of Renwick and the International Programme on Chemical Safety (IPCS). The composite factors for all the examined pesticides were less than 100. The present study indicated that in setting exposure levels it is important to incorporate kinetic and dynamic data, as they become available, rather than rely on default uncertainty factors, which are imprecise in many cases.     

Applying USEPA Risk Assessment Guidance in the 90s

Over the past decade, risk assessment has become increasingly relied upon for helping to make environmental management decisions. This trend has been accompanied by research and refinements in basic risk assessment methodologies to improve our ability to understand and evaluate the human health risks associated with chemical exposures.Despite this progress, significant uncertainties continue to be associated with the risk assessment process. These uncertainties typically derive from gaps in available data regarding chemical toxicity, and from difficulties in reliably estimating the magnitude of chemical exposures. Given these limitations, risk assessment is generally most valuable in evaluating relative risk; for example, when comparing alternatives to achieving a specified goal, setting priorities for protecting human health, or establishing procedures for properly allocating resources. Risk assessment can also be useful for developing regulatory benchmarks such as permit limits for air or water. In many cases, however, the limitations of the risk assessment process make it difficult (if not impossible) to reliably estimate an absolute level of risk, especially for a specific individual in an exposed population. In such cases, risk assessment can be seriously misapplied, and its results misinterpreted.This paper discusses some of the challenges that have been faced by the field of risk assessment during the 1990s. Current trends in risk assessment, and its use by regulatory agencies in making risk management decisions, are also described.     

Challenges and Research Needs for Risk Assessment of Pesticides for Registration in Africa

Risk assessment is necessary for registration and risk management of new pesticides. The aim of this article is to discuss challenges that risk assessors in Africa face when conducting risk assessment of pesticides. Risk assessment requires toxicity assessment, environmental fate studies, and the use of models for occupational, dietary, residential, and environmental exposure assessments. Toxicity studies are very costly with the result that toxicity data used to register pesticides in Africa are often sourced from northern hemisphere countries. Assessors also often use exposure modeling results from the northern hemisphere. This is not an ideal approach as occupational exposure is influenced by agricultural practices, climatic conditions, and other factors. Furthermore, residential exposure models require time-location-activity information, exposure factors, and toxicokinetic rate constants for particular pesticides. Dietary exposure assessment needs accurate and comprehensive local food consumption data. Authorities in African countries should therefore generate the required data, despite these being very costly and tedious. Authorities should also provide guidance on the type of models and standard scenarios for estimating predicted environmental concentrations in various environmental compartments. It is recommended that higher educational institutions in Africa should incorporate risk assessment in general and pesticide toxicity and exposure models in particular in their curricula.     

Human Health Risk Assessment for Environmental Exposure to Metals in the Catalan Stretch of the Ebro River,Spain

The aim of this study was to investigate the environmental impact and the human health risks associated with metals exposure in the Catalan stretch of the Ebro River, Spain. The concentrations of the following elements were determined in soils and tap water: As, Cd, Cr, Cu, Hg, Mn, Ni, and Pb. Carcinogenic and non-carcinogenic risks were separately assessed for adults and children. Relatively low metal concentrations in tap water were found. It indicates that water intake is not a relevant source of metals for human health impact in the area under evaluation. In turn, the levels of metals in soils were similar or less than those found in a number of recent worldwide surveys. The presence of industrial facilities located upstream the Ebro River, including a chloralkali plant, should not mean additional non-carcinogenic risks for the population living in the area. The results of the current study allow us to establish that the concentrations of most carcinogenic elements (with the exception of As) should not mean potential health risks for the local population. However, because of the relatively high levels of geological origin found for As, a continued monitoring of these elements would be desirable.     

Health Risk Assessment of Chemical Mixtures Exposure to Residents in the Lake Taihu Region,China

This study assessed the mixture health risk for the residents of China's Lake Taihu region posed by a Persistent Organic Pollutants (POPs) mixture of dichloro-diphenyl-trichloroethane (DDT) and hexachlorocyclohexane (HCH). Multiple-pathway exposure models were used for exposure assessment in order to estimate the DDT and HCH exposure dose. The DDT and HCH PBPK models were developed and used for consequence assessment in order to analyze the pollutant distribution and accumulation process in human tissues. The tissue dose hazard index (HI) was used to estimate the mixture health risk. The results showed that the total exposure doses for male residents and female residents were 4.01 × 10^{? 4}～ 7.67 × 10^{? 3} mg/kg/day and 3.73 × 10^{? 4}～ 6.75 × 10^{? 3} mg/kg/day for DDT, respectively, and 3.78 × 10^{? 4}～ 5.14 × 10^{? 3} mg/kg/day and 3.53 × 10^{? 4}～ 4.66 × 10^{? 3} mg/kg/day for HCH, respectively. The maximum tissue concentrations in fat for male and female residents reached 110.51 mg/l and 97.21 mg/l for DDT, respectively, and 189.66 mg/l and 171.72 mg/l for HCH, respectively. The tissue dose hazard indexes for male and female residents were 0.1472 ～ 2.4990 and 0.1377 ～ 2.2230, respectively, and the probabilities of the risk exceeding the acceptable risk (HI = 1) for male and female were 24.60% and 16.51%, respectively.     

Health Risk Assessment of Petrol Station Workers in the Inner City of Bangkok,Thailand, to the Exposure to BTEX and Carbonyl Compounds by Inhalation

The occupational health risk of petrol station workers from exposure to BTEX and carbonyl compounds via inhalation was estimated in the inner city of Bangkok. Personal sampling was performed within the workers’ breathing zone using 2,4 dinitrophenylhydrazine cartridges and charcoal glass tubes connected to a personal air pump during eight working hours at six petrol stations. BTEX and carbonyl compounds were quantitatively analyzed by GC/FID and HPLC/UV, respectively. Of all detectable BTEX and carbonyl compounds, the levels of the four most prevalent compounds (benzene, ethylbenzene, formaldehyde, and acetaldehyde) were used to assess the lifetime cancer risk and 95% confidence interval of the risk levels were found to be totally higher than acceptable criteria for benzene (1.82 × 10^–4–2.50 × 10^–4), formaldehyde (7.81 × 10^–6–1.04 × 10^–5), ethylbenzene (4.11 × 10^–6–5.52 × 10^–6), and acetaldehyde (1.39 × 10^–6–2.45 × 10^–6). Thus, petrol station workers in the inner city of Bangkok have a potentially high cancer risk through inhalation exposure. With respect to the noncarcinogenic agents, toluene, m,p-xylene, o-xylene, and propionaldehyde, all non-cancer health risk were within hazard quotients of 1 and of acceptable risk.     

Monte Carlo Simulation-Based Health Risk Assessment of Heavy Metal Soil Pollution: A Case Study in the Qixia Mining Area,China

In recent years, heavy metal pollution accidents have occurred in many regions of China, and the public has become increasingly concerned about its health. Based on a U.S. Environmental Protection Agency model and using Monte Carlo simulation techniques, this article presents a procedure for health risk assessment of heavy metal pollution. A case study was conducted in the Qixia lead and zinc mining area. Based on the magnitude of heavy metal contamination in the mine factory, vicinal Qixia scenic site and village, the potential health risk calculated for a lifetime of exposure (through ingestion and dermal contact) was determined as the cumulative carcinogenic and non-carcinogenic risk for workers, tourists, and local residents (including children and adults), respectively. The risk assessment indicated that the carcinogenic risk is not significant. However, Pb poses a significant cumulative non-carcinogenic risk, which tends to be serious for workers. Additionally, local children are more vulnerable than adults to the risks associated with heavy metal contamination. Accordingly, risk alleviation and preventive measures should be taken, especially for children and workers.     

Health risk assessment of residential exposure to cypermethrin among young children in agricultural communities in northeastern Thailand

This study aimed to identify factors associated with dermal exposure to cypermethrin and assess the health risks among young children in an agricultural community in Thailand. Face-to-face interviews were conducted with the parents/caregivers of 58 children (aged 1–3 years). Wipe samples were analyzed for cypermethrin by gas chromatography-microelectron capture detection (GC-µECD). Health risk assessments were based on the cypermethrin concentration on the children’s hands and feet. Spearman’s correlation indicated significant associations among cypermethrin concentrations on the hands, feet, floors/wooden beds, and toys (rho?=?0.438–0.613, p-value <0.001). Cypermethrin concentrations on the hands were significantly and inversely correlated with the child’s caregiver being the child’s mother and insecticide use (p?<?0.01). Concentrations on the feet were significantly correlated with insecticide use (p?<?0.05) and showering (p?<?0.01). The hazard quotient calculated from dermal exposure via the hands and feet showed no risk for potential noncarcinogenic effects (5.586?×?10^?5 in the dry season and 4.301?×?10^?4 in the wet season). These findings suggest that young children might not be at risk for cypermethrin exposure through the dermal route. Residential exposure among young children may be reduced by improved hygiene. Health risk assessments of environmental insecticide exposure via the oral and inhalation routes require further investigation.     

Assessment of Human Health Risk for an Area Impacted by a Large-Scale Metallurgical Refinery Complex in Hunan,China

Due to accelerated urbanization and reform of industrial structure in China, polluting industries in major cities have been closed or relocated. Consequently, large numbers of industrial sites were generated and the contaminated soils on and around these sites may pose risks to humans. This case study presents an estimation of human health risks for an area that is mainly impacted through air dispersion and deposition from a large-scale metallurgical refinery complex in Zhuzhou city, Hunan Province, China. Carcinogenic and non-carcinogenic risks posed by the contaminants were estimated under future industrial and residential land use scenarios. The result shows that adverse health effects may occur primarily through ingestion of soils contaminated with As, Cd, and Pb. The total carcinogenic risks of multiple contaminants for a large area exceed the acceptable risk level of 1 × 10^?5, and several localized hotspots, where the total hazard index exceeds 1 were identified. Soils in the Tongda site pose the highest carcinogenic risks and non-carcinogenic hazards. It is concluded that potential human health risks exist under the proposed redevelopment scenarios, and development of risk-based remediation strategies is recommended.     

Issues in Exposure and Dose Assessment for Epidemiology and Risk Assessment

Epidemiologic studies have been effective in identifying human environmental and occupational hazards. However, most epidemiologic data has been difficult to use in quantitative risk assessments because of the vague specification of exposure and dose. Toxicologic animal studies have used applied doses (quantities administered, or exposures with fixed duration) and well characterized end points to determine effects. However, direct use of animal data in human risk assessment has been limited by uncertainties in the extrapolation. The applied dose paradigm of toxicology is not suited for cross species extrapolation, nor for use in epidemiology as a dose metric because of the complexity of human exposures. Physiologically based pharmacokinetic (PBPK) modeling can estimate the time course of tissue concentrations in humans, given an exposure-time profile, and it has been used for extrapolating findings from animals to humans. It is proposed that human PBPK modeling can be used in appropriately designed epidemiologic studies to estimate tissue concentrations. Secondly, tissue time courses can be used to form dose metrics based on the type and time course of adverse effects. These dose metrics will strengthen the determination of epidemiologic dose-response relationships by reducing misclassification. Findings from this approach can be readily integrated into quantitative risk assessment.     

High-Throughput Exposure Assessment Tool (HEAT) for exposure-based prioritization of chemicals

Abstract

High-throughput methods are now routinely used to rapidly screen chemicals for potential hazard. However, hazard-based decision-making excludes important exposure considerations resulting in an incomplete estimation of chemical safety. Models to estimate exposure exist, but are generally unsuited to keep up with high-throughput demands. The High-Throughput Exposure Assessment Tool (HEAT) is designed to efficiently predict near-field exposure to consumers and workers via inhalation, oral and dermal routes. HEAT is based on well-known modeling algorithms and provides default model parameters to support reasonably conservative exposure estimates. Underlying chemical-specific data are uploaded or entered by the end user. HEAT’s main strength is the flexible tiered screening functionality, which enables exposure estimates for single or multiple chemicals simultaneously. Hypothetical case examples highlighting the application of HEAT to more complex exposure estimates for alternative and aggregate assessments are provided.     

Evaluation of Potential Exposure to Metals in Laundered Shop Towels

We reported in 2003 that exposure to metals on laundered shop towels (LSTs) could exceed toxicity criteria. New data from LSTs used by workers in North America document the continued presence of metals in freshly laundered towels. We assessed potential exposure to metals based on concentrations of metals on the LSTs, estimates of LST usage by employees, and the transfer of metals from LST-to-hand, hand-to-mouth, and LST-to-lip, under average- or high-exposure scenarios. Exposure estimates were compared to toxicity criteria. Under an average-exposure scenario (excluding metals’ data outliers), exceedances of the California Environmental Protection Agency, U.S. Environmental Protection Agency, and the Agency for Toxic Substances and Disease Registry toxicity criteria may occur for aluminum, cadmium, cobalt, copper, iron, and lead. Calculated intakes for these metals were up to more than 400-fold higher (lead) than their respective toxicity criterion. For the high-exposure scenario, additional exceedances may occur, and high-exposure intakes were up to 1,170-fold higher (lead) than their respective toxicity criterion. A sensitivity analysis indicated that alternate plausible assumptions could increase or decrease the magnitude of exceedances, but were unlikely to eliminate certain exceedances, particularly for lead.     

Recent Developments in Nanotechnology and Risk Assessment Strategies for Addressing Public and Environmental Health Concerns

Nanotechnology is a novel emerging technology that allows the manipulation of materials at the scale comparable to the size of a single molecule (i.e., < 100 nm). There have been many new developments in this technology, resulting in complex exposure and health risk implications. Nanotechnology offers major benefits to humankind; however, there is growing concern regarding the potential adverse interactions of engineered nanoparticles at cellular or sub-cellular levels. The nanotech community is therefore experiencing growing calls for legislation to minimize or prevent exposure to nanoparticles. This article focuses on recent developments in nanotechnology including current manufacturing techniques, uses of nanoscale particles, and implications for particle toxicity and human exposure pathways. Current risk assessment methods are reviewed in the context of nanoparticle exposure routes and regulation for human and environmental health protection. This study provides a better understanding of the factors governing risks from nanoparticles and current strategies for protecting environmental and public health.