Wattasit Siriwong

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

ABSTRACT 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).

Neurobehavioral effects of exposure to organophosphates and pyrethroid pesticides among Thai children

The use of pesticides for crop production has grown rapidly in Thailand during the last decade, resulting in significantly greater potential for exposure among children living on farms. Although some previous studies assessed exposures to pesticides in this population, no studies have been conducted to evaluate corresponding health effects. Twenty-four children from a rice farming community (exposed) and 29 from an aquaculture (shrimp) community (control) completed the study. Participants completed a neurobehavioral test battery three times at 6 month intervals: Session I: preliminary orientation; Session II: high pesticide use season; Session III: low pesticide-use season. Only sessions II and III were used in the analyses. High and low pesticide use seasons were determined by pesticide use on rice farms. Urinary metabolites of organophosphates (OPs) and pyrethroids (PYR) were analyzed from first morning void samples collected the day of neurobehavioral testing. Rice farm participants had significantly higher concentrations of dialkylphosphates (DAPs) (common metabolites of OPs) and TCPy (a specific metabolite of chlorpyrifos) than aquaculture farm children during both seasons. But, TCPy was significantly higher during the low rather than the high pesticide use season for both participant groups. Rice farm children had significantly higher DCCA, a metabolite of PYR, than aquaculture participants only during the high exposure season. Otherwise, no significant differences in PYR metabolites were noted between the participant groups or seasons. No significant adverse neurobehavioral effects were observed between participant groups during either the high or low pesticide use season. After controlling for differences in age and the Home Observation for Measurement of the Environment (HOME) scores, DAPs, TCPy, and PYR were not significant predictors of adverse neurobehavioral performance during either season. Increasing DAP and PYR metabolites predicted some relatively small improvement in latency of response. However, due to the small sample size and inability to characterize chronic exposure, any significant differences observed should be regarded with caution. Moreover although not statistically significant, confidence intervals suggest that small to moderate adverse effects of pesticide exposure cannot be ruled out for some indicators of neurobehavioral performance.

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

ABSTRACT 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 Lanchesters 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.

Organophosphate Pesticide Exposure in School-Aged Children Living in Rice and Aquacultural Farming Regions of Thailand

ABSTRACT Organophosphate pesticides (OPs) are widely used in agricultural sectors in Thailand. Previous studies have documented that children residing in agricultural areas have higher exposure to OPs than children living in other residential areas. The objective of this study was to quantify urinary biomarkers of OP exposure and determine the environmental conditions and activities that predict their levels among children living in Central Thailand farming regions. In October 2011, 53 6–8-year-old participants were recruited from Pathum Thani Province, Thailand. Twenty-four lived in rice farming communities at Khlong Luang District where OPs are the pesticides used frequently. Twenty-nine participants, living in aquacultural farming communities at Lum Luk Ka District where OPs are not used, were recruited to serve as controls for pathways of exposure (e.g., residential, dietary) other than occupational/paraoccupational exposures encountered in rice farming. Household environments and participants’ activities were assessed using a parental structured interview. Urine samples (first morning voids) were collected from participants for OP urinary metabolite (i.e., dialkylphosphates [DAPs] and 3,5,6-trichloro-2-pyridinol [TCPy]) measurements. The levels of most urinary OP metabolites were significantly higher in participants who lived in a rice farming community than those who lived in an aquacultural farming community (P < .05). The results from linear regression analysis revealed that the frequency of OP application on rice farms (∑DAP: P = .001; TCPy: P = .001) and living in a rice farming community (∑DAP: P = .009; TCPy: P < .001) were significant predictors of urinary DAP metabolite levels in participants. Increasing TCPy levels were significantly related to proximity to rice farm (P = .03), being with parent while working on a farm (P = .02), playing on a farm (P = .03), and the presence of observable dirt accumulated on the child’s body (P = .02). In conclusion, OP metabolite levels among children who live in rice farming communities were strongly influenced by farming activity, household environments, and child behaviors, suggesting that these are the primary pathways in which children living in these agricultural communities in Thailand were exposed to OPs.

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

ABSTRACT 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.

Non-Carcinogenic Hazard Maps of Heavy Metal Contamination in Shallow Groundwater for Adult and Aging Populations at an Agricultural Area in Northeastern Thailand

ABSTRACT The Hua-ruea sub-district has long been a major agricultural area of Thailand. Shallow groundwater from farm wells is a main source of drinking water for most locals. This study assessed the human health hazards associated with consuming groundwater contaminated with heavy metals among adults age 15–60 years and the aging, greater than 60 years. Twelve groundwater wells were sampled in the Hua-ruea agricultural area. The results showed adults’ average groundwater consumption was high at 3.6 ± 2.1 L/day/person and for the aging group was 2.6 ± 1.0 L/day/person. The hazard quotients for As, Cu, Pb, and Zn exceeded 1 among both the adult and aging populations. Residents of the Hua-ruea subdistrict may be at risk of developing diseases from consumption of water contaminated with these four metals at seven of the 12 wells. These wells are located in intensely cultivated chili fields. All non-carcinogenic hazards of all heavy metals were higher in adults than for the aging population due to a higher intake rate of water by the former. One well had the highest hazard index, 91.8 and 66.2 for adults and the aging, respectively. This study suggested that local people living in intensively agricultural areas should take precautions before drinking contaminated groundwater.

Multi-approach model for improving agrochemical safety among rice farmers in Pathumthani, Thailand.

The large-scale use of agrochemicals has raised environmental and human health concerns. A comprehensive intervention strategy for improving agrochemical safety among rice farmers in Thailand is lacking. The objective of this study is to develop a model in order to improve farmers’ health and prevent them from being exposed to agrochemical hazards, in addition to evaluating the effectiveness of the intervention in terms of agrochemical safety. This study was conducted between October 2009 and January 2011. It measures changes in the mean scores of agrochemical knowledge, health beliefs, agrochemical use behaviors, and in-home pesticide safety. Knowledge of agrochemical use constitutes a basic knowledge of agrochemicals and agrochemical safety behaviors. Health beliefs constitute perceived susceptibility, severity, benefits, and barriers to using agrochemicals. Agrochemical use behaviors include self-care practices in terms of personal health at specific times including before spraying, while spraying, during storage, transportation, waste management, and health risk management. Fifty rice farmers from Khlong Seven Community (study group) and 51 rice farmers from Bueng Ka Sam community (control group) were randomly recruited with support from community leaders. The participants were involved in a combination of home visits (ie, pesticide safety assessments at home) and community participatory activities regarding agrochemical safety. This study reveals that health risk behaviors regarding agrochemical exposure in the study area are mainly caused by lack of attention to safety precautions and the use of faulty protective gear. After 6 months, the intervention program showed significant improvements in the overall scores on knowledge, beliefs, behaviors, and home pesticide safety in the study group (P < 0.05). Therefore, this intervention model is effective in improving agrochemical safety behaviors among Khlong Seven Community rice farmers. These findings demonstrate that a multi-approach model for improving agrochemical safety behaviors can lead to sustainable prevention of agrochemical hazards for farmers.

Health risk behaviors associated with agrochemical exposure among rice farmers in a rural community, Thailand: a community-based ethnography

The study objective was to evaluate health beliefs and behaviors associated with agrochemical exposure among rice farmers. We applied the Health Belief Model, community-based ethnography, and public health risk assessment for this study. Data were collected from 101 rice farmers in Khlong Seven community between January and June 2010. Data comprised observations, unstructured and semistructured interviews, and focus group discussions. We showed that farmers had moderate levels of perceived susceptibility to, severity of, benefits of, and barriers to using agrochemicals safely. The major risk factors related to agrochemical exposure resulted from the misuse of pesticides, including erroneous beliefs of farmers regarding pesticide toxicity, the use of faulty spraying equipment, the lack of proper maintenance of spraying equipment, or the lack of protective gear and appropriate clothing. An intervention program is necessary to improve safety with regard to agrochemicals in the rice Khlong Seven community.

Cancer risk analysis of benzene, formaldehyde and acetaldehyde on gasoline station workers

Background: Benzene, formaldehyde and acetaldehyde are carcinogenic substances to which gasoline station workers are most likely exposed via inhalation. To evaluate these compounds in the ambient air of gasoline stations, the inhalation exposure test on workers was performed and assessed. By the appropriate intervention of wearing mask and hand washing during work shift, we determined whether or not there is cancer risk to the exposure of benzene, formaldehyde and acetaldehyde using urinary biomarkers. Methods: A cross sectional study was conducted in 38 workers of 6 gasoline stations in Pathumwan District, Bangkok, Thailand. Inhalation and ambient air concentrations of benzene, formaldehyde and acetaldehyde were evaluated by GC/FID and HPLC/UV detectors. Urinary trans, trans-muconic acid (t,t-MA), formaldehyde and acetaldehyde concentrations detected in gasoline workers before and after appropriate intervention were analyzed by GC/FID. Results: The average inhalation exposure concentrations of benzene, formaldehyde and acetaldehyde were 195.56, 12.60 and 5.74 µg/m3, respectively. The level of benzene exposure was significantly higher than the ambient air level (independent t-test, p < 0.01). The average lifetime cancer risk of the workers exposed to benzene, formaldehyde and acetaldehyde was determined at the values of 2.15E-04, 1.27E-05 and 2.69E-06, respectively. Benzene and formaldehyde values were higher than an acceptable criteria defined as 1E-06. The amount of urinary t,t-MA, formaldehyde and acetaldehyde in the workers daily after 7-days appropriate intervention (wearing masks as personal protective equipment (PPE) and hand washing) was decreased. Formaldehyde and acetaldehyde, which were detected in urine, showed significantly lower than before intervention (pair t-test, p < 0.001). Conclusions: Results from our study confirmed that the gasoline workers have high chances of cancer risk from daily exposure to benzene and formaldehyde. The urinary’s t,t-MA, formaldehyde and acetaldehyde could be considerably used as biomarkers in gasoline station workers. An appropriate intervention, using PPE and hand washing, could reduce the cancer risk.

Risk Assessment for Dermal Exposure of Organochlorine Pesticides for Local Fishermen in the Rangsit Agricultural Area, Central Thailand

ABSTRACT Organochlorine pesticides (OCPs) used in agriculture and for public health purposes were banned in Thailand over the past decade; however, their persistent residues have been found in several agricultural areas of the country. This may result in adverse effects to human populations. This study investigated the concentration of organochlorine pesticides residues (OCPRs) in surface water and evaluated the potential cancer risk associated with dermal contact of the local fisherman fishing in the Khlong 7 canal, Rangsit agricultural area, central Thailand. Water samples were extracted using liquid-liquid extraction (LLE) 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 or ng/ml) levels, that is, ∑ Endosulfan (α -, β -, and -sulfate) 0.082 ng/ml > DDT and derivatives 0.019 ng/ml > ∑ HCH (α -, γ -, β -, and δ -HCH) 0.014 ng/ml > aldrin and dieldrin 0.007 ng/ml > heptachlor and heptachlor epoxide 0.0068 ng/ml > endrin and endrin aldehyde 0.005 ng/ml > methoxychlor 0.001 ng/ml, respectively. Using the worst-case scenario defined as the reasonable maximum exposure (RME) to assess the potential cancer risk, five OCPs (dieldrin, 4,4′ -DDT, β -HCH, heptachlor, and heptachlor epoxide) may pose a risk of concern on a lifetime human carcinogenesis greater than one in a million.