Environmental health risk assessment of dioxin exposure through foods in a Dioxin hot spot—Bien Hoa City, Vietnam

This study used the Australian Environmental Health Risk Assessment Framework to assess the human health risk of dioxin exposure through foods for local residents in two wards of Bien Hoa City, Vietnam. These wards are known hot-spots for dioxin and a range of stakeholders from central government to local levels were involved in this process. Publications on dioxin characteristics and toxicity were reviewed and dioxin concentrations in local soil, mud, foods, milk and blood samples were used as data for this risk assessment. A food frequency survey of 400 randomly selected households in these wards was conducted to provide data for exposure assessment. Results showed that local residents who had consumed locally cultivated foods, especially fresh water fish and bottom-feeding fish, free-ranging chicken, duck, and beef were at a very high risk, with their daily dioxin intake far exceeding the tolerable daily intake recommended by the WHO. Based on the results of this assessment, a multifaceted risk management program was developed and has been recognized as the first public health program ever to have been implemented in Vietnam to reduce the risks of dioxin exposure at dioxin hot-spots.

The effectiveness of an intervention in reducing risk of dioxin exposure in Da Nang : changes in community knowledge, attitudes and prevention practices after 2.5 years

Introduction Environmental and biological samples taken around Da Nang Air Base have shown elevated levels of dioxin over many years [1-3]. A pre-intervention knowledge, attitudes and practices (KAP) survey (2009), a risk reduction program (2010) and a post intervention KAP survey (2011) were undertaken in four wards surrounding Danang Airbase. A follow-up evaluation was undertaken in 2013. Methods A KAP survey was implemented among 400 randomly selected food handlers. Eleven indepth interviews and four focus group discussions were also undertaken. Results The knowledge of respondents remained positive and/or improved at 2.5 years follow-up. There were no significant differences in attitudes toward preventing dioxin exposure across surveys; most respondents were positive in all three surveys. An increase in households (69.5%) undertaking measures to prevent exposure was observed, which was higher than in the pre-intervention survey (39.6%) and post- intervention survey (60.4%) (χ2 = 95.6; p < 0.001). The proportion of respondents practicing appropriate preventive measures was also significantly improved. Conclusions Despite most of the intervention program’s activities ceasing in 2010, the risk reduction program has resulted in positive outcomes over the longer-term, with many knowledge and attitude measures remaining stable or imporving. Some KAP indicators decreased, but these KAP indicators were still significantly higher than the pre-intervention levels.

Environmental health risk assessment of dioxin in foods at the two most severe dioxin hot spots in Vietnam

Background Bien Hoa and Da Nang airbases were bulk storages for Agent Orange during the Vietnam War and currently are the two most severe dioxin hot spots. Objectives This study assesses the health risk of exposure to dioxin through foods for local residents living in seven wards surrounding these airbases. Methods This study follows the Australian Environmental Health Risk Assessment Framework to assess the health risk of exposure to dioxin in foods. Forty-six pooled samples of commonly consumed local foods were collected and analyzed for dioxin/furans. A food frequency and Knowledge–Attitude–Practice survey was also undertaken at 1000 local households, various stakeholders were involved and related publications were reviewed. Results Total dioxin/furan concentrations in samples of local “high-risk” foods (e.g. free range chicken meat and eggs, ducks, freshwater fish, snail and beef) ranged from 3.8 pg TEQ/g to 95 pg TEQ/g, while in “low-risk” foods (e.g. caged chicken meat and eggs, seafoods, pork, leafy vegetables, fruits, and rice) concentrations ranged from 0.03 pg TEQ/g to 6.1 pg TEQ/g. Estimated daily intake of dioxin if people who did not consume local high risk foods ranged from 3.2 pg TEQ/kg bw/day to 6.2 pg TEQ/kg bw/day (Bien Hoa) and from 1.2 pg TEQ/kg bw/day to 4.3 pg TEQ/kg bw/day (Da Nang). Consumption of local high risk foods resulted in extremely high dioxin daily intakes (60.4–102.8 pg TEQ/kg bw/day in Bien Hoa; 27.0–148.0 pg TEQ/kg bw/day in Da Nang). Conclusions Consumption of local “high-risk” foods increases dioxin daily intakes far above the WHO recommended TDI (1–4 pg TEQ/kg bw/day). Practicing appropriate preventive measures is necessary to significantly reduce exposure and health risk.

New strategy toward dioxin risk reduction for local residents surrounding severe dioxin hotspots in Vietnam

Background A public health intervention program with active involvement of local related stakeholders was piloted in the Bien Hoa dioxin hot spot (2007-2009), and then expanded to the Da Nang dioxin hot spot in Vietnam (2009-2011). It aimed to reduce the risk of dioxin exposure through foods for local residents. This article presents the results of the intervention in Da Nang. Methodology To assess the results of this intervention program, pre-intervention and post-intervention knowledge-attitude-practice (KAP) surveys were implemented in 400 households, randomly selected from four wards surrounding Da Nang Airbase in 2009 and 2011, respectively. Results After the intervention, the knowledge on the existence of dioxin in food, dioxin exposure pathways, potential high risk foods and preventive measures significantly increased (p < 0.05). 98% were willing to follow advice on preventing dioxin exposure. Practices to reduce the risk of dioxin exposure also statistical significantly improved (p<0.05). After intervention, 60.4% of households undertook exposure preventive measures, significantly higher than that of the pre-intervention survey (39.6%; χ2 =40.15 , P<0.001). High risk foods had quite low rates of daily consumption (from 0% to 2.5%) and were significantly reduced (p<0.05). Conclusions This is seen as an effective intervention strategy toward reducing the risk of human exposure to dioxin at dioxin hot spots. While greater efforts are needed for remediating dioxin polluted areas inside airbases, there is also evidence to suggest that, during the past four decades, pollution has been expanding to the surrounding areas. For this reason, this model should be quickly expanded to the remaining dioxin hot spots in Vietnam to further reduce the exposure risk in these areas.

Dioxin risk reduction programme at the most severe dioxin hot spot in Vietnam: Residual knowledge, attitude and practices five years post intervention

Bien Hoa Airbase was one of the bulk storage and supply facilities for defoliants during the Vietnam War. Environmental and biological samples taken around the airbase have elevated levels of dioxin. In 2007, a pre-intervention knowledge, attitude and practice (KAP) survey of local residents living in Trung Dung and Tan Phong wards was undertaken regarding appropriate strategies to reduce dioxin exposure. A risk reduction programme was implemented in 2008 and post-intervention KAP surveys were undertaken in 2009 and 2013 to evaluate the longer term impacts. Quantitative assessment was undertaken via a KAP survey in 2013 among 600 local residents randomly selected from the two intervention wards and one control ward (Buu Long). Eight in-depth interviews and two focus group discussions were also undertaken for qualitative assessment. Most programme activities had ceased and dioxin risk communication activities had not been integrated into local routine health education programmes; however, main results generally remained and were better than that in Buu Long. In total, 48.2% of households undertook measures to prevent exposure, higher than those in pre- and post-intervention surveys (25.8% and 39.7%) and the control ward (7.7%). Migration and the sensitive nature of dioxin issues were the main challenges for the programme's sustainability

Knowledge, attitudes and practices to reduce exposure among residents living near Danang dioxin hot spot : 2.5 years after a preventative intervention

Da Nang Airbase in Viet Nam served as a bulk storage and supply facility for Agent Orange and other herbicides during Operation Ranch Hand 1961-1971[1]. Studies have shown that environmental and biological samples taken around the airbase site have elevated levels of dioxin [1-3]. Residents living in the vicinity of the airbase are at risk of exposure to dioxin in soil, water and mud and particularly through the consumption of local contaminated food. In 2009, a pre-intervention cross sectional survey was undertaken. This survey examined the knowledge, attitudes and practices (KAP) of householders living near Da Nang Airbase, relevent to reducing dioxin exposure through contaminated food. The results showed that despite living near a severe dioxin hot spot, the residents had very limited knowledge of both exposure risk and measures to reduce exposure to dioxin[4]. In response, the Vietnam Public Health Association (VPHA) and Da Nang Public Health Association implemented a risk reduction program at four residential wards in the vicinities of the Da Nang Airbase in 2010. A post intervention KAP survey was under taken in 2011, and the results showed that knowledge of the existence of dioxin in food, dioxin exposure pathways, potential high risk foods, and preventive measures was significantly enhanced. This new study monitored KAP 2.5 years after the intervention through a 2013 survey of food handlers from 400 households that were randomly selected from the four intervention wards. The results show that most of the positive outcomes remained stable or had increased; some KAP indicators decreased compared to those in the post-intervention survey, but were still significantly higher than the pre-intervention levels. In 2014, these findings will be incorporated with qualitative assessments and the results of laboratory analysis of dioxin concentrations in foods in Da Nang and Bien Hoa dioxin hot spots to comprehensively assess the sustained effects of the intervention.

Sustainability of public health interventions to reduce the risk of dioxin exposure at severe dioxin hot spots in Vietnam

Severe dioxin contamination at Bien Hoa and Da Nang airbases, Vietnam is of international concern. Public Health risk reduction programs were implemented in Bien Hoa in 2007-2009 and in Da Nang in 2009-2011. In 2009 and 2011 we reported the encouraging results of these interventions in improving the knowledge, attitude and practices (KAP) of local residents in reducing the dioxin exposure risk through foods. In 2013 we revisited these dioxin hot spots, aimed to evaluate whether the results of the intervention were maintained and to identify factors affecting the sustainability of the programs. To assess this, 16 in-depth interviews, six focus group discussions, and pre and post intervention KAP surveys were undertaken. 800 respondents from six intervention wards and 200 respondents from Buu Long Ward (the control site) were randomly selected to participate in the surveys. The results showed that as of 2013, the programs were rated as "moderately sustained" with a score of 3.3 out of 5.0 (cut off points 2.5 to <3.5) for Bien Hoa, and "well sustained" with a score of 3.8 out of 5.0 (cut off points 3.5 to <4.5) for Da Nang. Most formal intervention program activities had ceased and dioxin risk communication activities were no longer integrated into local routine health education programs. However, the main outcomes were maintained and were better than that in the control ward. Migration, lack of official guidance from City People's Committees and local authorities as well as the politically sensitive nature of dioxin issues were the main challenges for the sustainability of the programs.

Urinary excretion of cadmium among Torres Strait Islanders (Australia) at risk of elevated dietary exposure through traditional foods

This study explored urinary cadmium levels among Torres Strait Islanders in response to concerns about potential health impact of high levels of cadmium in some traditional seafood (dugong and turtle liver and kidney). Cadmium levels were measured by inductively coupled mass spectrometry in de-identified urine samples collected during general screening programs in 1996 in two communities with varying dugong and turtle catch statistics. Statistical analysis was performed to identify links between cadmium levels and demographic and background health information. Geometric mean cadmium level among the sample group was 0.83 mu g/g creatinine with 12% containing over 2 mu g/g creatinine. Cadmium level was most strongly associated with age (46% of variation), followed by sex (females > males, 7%) and current smoking status (smokers > non-smokers, 4.7%). Adjusting model conditions suggested further positive associations between cadmium level and diabetes (p = 0.05) and residence in the predicted higher exposure community (p = 0.07). Positive correlations between cadmium and body fat in bivariate analysis were eliminated by control for age and sex. This study found only suggestive differences in cadmium levels between two communities with predicted variation in exposure from traditional foods. However, the data indicate that factors linked with higher cadmium accumulation overlap with those of renal disease risk (i.e. older, females, smokers, diabetes) and suggest that levels may be sufficient to contribute to renal pathology. More direct assessment of exposure and health risks of cadmium to Torres Strait Islanders is needed given the disproportionate level of diet-related disease and the cultural importance of dugong and turtle. This study highlights the need to consider social and cultural variation in exposure and to de. ne "safe'' cadmium levels during diabetes given its rising global prevalence.

Complex Interactions between Dioxin-Like and Non-Dioxin-Like Compounds for in Vitro Cellular Responses: Implications for the Identification of Dioxin Exposure Biomarkers

Despite considerable advances in reducing the production of dioxin-like toxicants in recent years, contamination of the food chain still occasionally occurs resulting in huge losses to the agri-food sector and risk to human health through exposure. Dioxin-like toxicity is exhibited by a range of stable and bioaccumulative compounds including polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), produced by certain types of combustion, and man-made coplanar polychlorinated biphenyls (PCBs), as found in electrical transformer oils. While dioxinergic compounds act by a common mode of action making exposure detection biomarker based techniques a potentially useful tool, the influence of co-contaminating toxicants on such approaches needs to be considered. To assess the impact of possible interactions, the biological responses of H4IIE cells to challenge by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in combination with PCB-52 and benzo-a-pyrene (BaP) were evaluated by a number of methods in this study. Ethoxyresorufin-O-deethylase (EROD) induction in TCDD exposed cells was suppressed by increasing concentrations of PCB-52, PCB-153, or BaP up to 10 mu M. BaP levels below 1 mu M suppressed TCDD stimulated EROD induction, but at higher concentrations, EROD induction was greater than the maximum observed when cells were treated with TCDD alone. A similar biphasic interaction of BaP with TCDD co-exposure was noted in the AlamarBlue assay and to a lesser extent with PCB-52. Surface enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF) profiling of peptidomic responses of cells exposed to compound combinations was compared. Cells co-exposed to TCDD in the presence of BaP or PCB-52 produced the most differentiated spectra with a substantial number of non-additive interactions observed. These findings suggest that interactions between dioxin and other toxicants create novel, additive, and non-additive effects, which may be more indicative of the types of responses seen in exposed animals than those of single exposures to the individual compounds.

Lead exposure through gestation-only caused long-term learning/memory deficits in young adult offspring

Numerous observations in clinical and preclinical studies indicate that the developing brain is particular sensitive to lead (Pb)'s pernicious effects. However, the effect of gestation-only Pb exposure on cognitive functions at maturation has not been studied. We investigated the potential effects of three levels of Pb exposure (low, middle, and high Pb: 0.03%, 0.09%, and 0.27% of lead acetate-containing diets) at the gestational period on the spatial memory of young adult offspring by Morris water maze spatial learning and fixed location/visible platform tasks. Our results revealed that three levels of Pb exposure significantly impaired memory retrieval in male offspring, but only female offspring at low levels of Pb exposure showed impairment of memory retrieval. These impairments were not due to the gross disturbances in motor performance and in vision because these animals performed the fixed location/visible platform task as well as controls, indicating that the specific aspects of spatial learning/memory were impaired. These results suggest that exposure to Pb during the gestational period is sufficient to cause long-term learning/memory deficits in young adult offspring. (C) 2003 Elsevier Inc. All rights reserved.

Exposure to foods’ non-taste sensory properties: a nursery intervention to increase children’s willingness to try fruit and vegetables

Activities that engage young children with the sensory properties of foods are popular with nursery schools, despite the lack of evidence for their efficacy in increasing children's consumption of healthy foods. This study provides the first empirical exploration of the effectiveness of a non-taste sensory activity program in a nursery school setting. Ninety-two children aged between 12 and 36 months were allocated to either an intervention group, who took part in looking, listening, feeling and smelling activities with unusual fruits and vegetables every day for four weeks, or to a non-intervention control group. In a subsequent mealtime taste test, children touched and tasted more of the vegetables to which they had been familiarized in their playtime activities than of a matched set of non-exposed foods. The results demonstrate that hands-on activities with unfamiliar fruits and vegetables can enhance children’s willingness to taste these foods, and confirm the potential for such activities to support healthy eating initiatives.

Polybrominated diphenyl ethers: Potential human exposure through household dust and dryer lint

This MPH thesis consists of (1) literature review of the relatively new synthetic persistent organic pollutants (POP), polybrominated diphenyl ethers (PBDEs), a type of flame retardant posing a potential public health hazard, (2) Presentation of data on PBDE levels in dryer lint from Dallas, TX and Hamburg, Germany. ^ PBDEs are used as additive fire retardants in plastics, polyurethane foam and electronic equipment to reduce flammability and thus save life and property. PBDEs have been widely used beginning in the 1970s. They resemble polychlorinated biphenyls (PCBs) in structure and toxicity. PBDEs are found in environmental sediments, sludges, and wildlife and even in human blood, milk and tissues. ^ PBDEs, due to their lipophilicity, accumulate in fat and other tissues and biomagnify up the food chain, with increasing concentrations. Animal studies have suggested potential health effects including thyroid disruption, permanent learning and memory impairment, fetal malformations, developmental neurotoxicity and, at high doses, possibly cancer. ^ PBDE levels are increasing in blood and breast milk in North America, but PBDEs intake unlike PCBs appears to be not primarily through food; food PBDE levels in the U.S. are not markedly higher than in Europe yet U.S. human blood and milk levels are much higher. For this reason various exposure pathways including PBDE contaminated dust and air have been studied to better characterize routes of PBDE intake into humans. ^ The scientific literature on PBDE levels in household dust reports higher PBDE concentration in dust than that found in dryer lint; levels in the U.S are elevated compared to other countries with congeners such as BDE 47, 99, 100 and 209 predominating. The United Kingdom has elevated BDE 209 due to high usage of Deca commercial mixture. These studies suggest that indoor PBDE contamination through household dust could be a potential source of PBDE exposure and body burden especially in young children. ^ PBDE levels in dryer lint from U.S ranged from 321 to 3073 ng/g (Mean: 1138 ng/g, Median: 803 ng/g) and from Germany were from 330 to 2069 ng/g (Median: 71ng/g, Mean: 361 ng/g). High median levels in U.S samples indicate contamination of lint with PBDEs although the source of the PBDEs in lint may be from dryer electrical components or air deposition onto clothes, lint may be one source of PBDE exposure to humans. ^

Application of mathematical models to mycotoxins children risk assessment: a case study of Portuguese children exposure to co-occurring mycotoxins in processed cereal-based foods

People, animals and the environment can be exposed to multiple chemicals at once from a variety of sources, but current risk assessment is usually carried out based on one chemical substance at a time. In human health risk assessment, ingestion of food is considered a major route of exposure to many contaminants, namely mycotoxins, a wide group of fungal secondary metabolites that are known to potentially cause toxicity and carcinogenic outcomes. Mycotoxins are commonly found in a variety of foods including those intended for consumption by infants and young children and have been found in processed cereal-based foods available in the Portuguese market. The use of mathematical models, including probabilistic approaches using Monte Carlo simulations, constitutes a prominent issue in human health risk assessment in general and in mycotoxins exposure assessment in particular. The present study aims to characterize, for the first time, the risk associated with the exposure of Portuguese children to single and multiple mycotoxins present in processed cereal-based foods (CBF). Portuguese children (0-3 years old) food consumption data (n=103) were collected using a 3 days food diary. Contamination data concerned the quantification of 12 mycotoxins (aflatoxins, ochratoxin A, fumonisins and trichothecenes) were evaluated in 20 CBF samples marketed in 2014 and 2015 in Lisbon; samples were analyzed by HPLC-FLD, LC-MS/MS and GC-MS. Daily exposure of children to mycotoxins was performed using deterministic and probabilistic approaches. Different strategies were used to treat the left censored data. For aflatoxins, as carcinogenic compounds, the margin of exposure (MoE) was calculated as a ratio of BMDL (benchmark dose lower confidence limit) to the aflatoxin exposure. The magnitude of the MoE gives an indication of the risk level. For the remaining mycotoxins, the output of exposure was compared to the dose reference values (TDI) in order to calculate the hazard quotients (ratio between exposure and a reference dose, HQ). For the cumulative risk assessment of multiple mycotoxins, the concentration addition (CA) concept was used. The combined margin of exposure (MoET) and the hazard index (HI) were calculated for aflatoxins and the remaining mycotoxins, respectively. 71% of CBF analyzed samples were contaminated with mycotoxins (with values below the legal limits) and approximately 56% of the studied children consumed CBF at least once in these 3 days. Preliminary results showed that children exposure to single mycotoxins present in CBF were below the TDI. Aflatoxins MoE and MoET revealed a reduced potential risk by exposure through consumption of CBF (with values around 10000 or more). HQ and HI values for the remaining mycotoxins were below 1. Children are a particularly vulnerable population group to food contaminants and the present results point out an urgent need to establish legal limits and control strategies regarding the presence of multiple mycotoxins in children foods in order to protect their health. The development of packaging materials with antifungal properties is a possible solution to control the growth of moulds and consequently to reduce mycotoxin production, contributing to guarantee the quality and safety of foods intended for children consumption.