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.

Estimation of reference values for dioxin, furan, and PCB congener concentrations for the Australian population

Population-representative data for dioxin and PCB congener concentrations are available for the Australian population based on measurements in age- and gender-specific serum pools.1 Such data provide a basis for characterizing the mean concentrations of these compounds in the population, but do not provide information on the inter-individual variation in serum concentrations that may exist in the population within an age- and gender-specific group. Such variation may occur due to inter-individual differences in long-term exposure levels or elimination rates. Reference values are estimates of upper percentiles (often the 95th percentile) of measured values in a defined population that can be used to evaluate data from individuals in the population in order to identify concentrations that are elevated, for example, from occupational exposures.2 The objective of this analysis is to estimate reference values corresponding to the 95th percentile (RV95s) for Australia on an age-specific basis for individual dioxin-like congeners based on measurements in serum pools from Toms and Mueller (2010).

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.

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.

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.

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.

Environmental health risk assessment of dioxin in foods and the sustainability of public health interventions at severe dioxin hot spots in Vietnam

This study assessed environmental health risk from dioxin in foods and sustainability of risk reduction programs at two heavily contaminated former military sites in Vietnam. The study involved 1000 household surveys, analysis of food samples and in-depth discussions with residents and officials. The findings indicate that more than 40 years after the war, local residents still experience high exposure to dioxin if they consume local high risk foods. Public health intervention programs were rated moderately to well sustained. Internal migration, and lack of clear, official guidance and sensitivity regarding dioxin issues were the main challenges for sustainability of prevention programs.

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.

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

A preliminary study on assessing body burden of persistent organic pollutants (POPs) in infants through analysis of faeces

Most persistent organic pollutants (POPs) like polychlorinated biphenyls (PCBs), a range of polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs) are readily absorbed (via the ingestion and inhalation) and accumulate in fatty tissue, including adipose tissue and human milk [1]. Health effects related to exposure to these chemicals may include neurological effects, altered functioning of the nervous system and/or endocrine disruption [2-4]. The burden of environmental disease is recognized as much higher for children than adults, especially in young children under 5 years of age worldwide [5]. There is increased concern regarding the environmental impact on the health of children who have been disproportionately affected by environmental problems. For example they may be subjected to relatively higher exposure, have greater physiological susceptibility and/or suffer more extreme consequences due to growth [6-9]. It is therefore worthwhile to assess the correlation between burden of disease and exposure to xenobiotic chemical pollutants like POPs. Such assessment may provide guidance for legislative changes regarding chemical bans and give reliable advice to parents including lactating mothers.

Identification of theta-class glutathione S-transferase in liver cytosol of the marmoset monkey

The presence of theta-class glutathione S-transferase (GST) in marmoset monkey liver cytosol was investigated. An anti-peptide antibody targeted against the C-terminus of rGSTT1 reacted with a single band in marmoset liver cytosol that corresponded to a molecular weight of 28 kDa. The intensity of the immunoreactive band was not affected by treatment of marmoset monkeys with 2,3,7,8-tetrachlorodibenzo-p-dioxin, phenobarbitone, rifampicin or clofibric acid. Similarly, activity towards methyl chloride (MC) was unaffected by these treatments. However, GST activity towards 1,2-epoxy3-(p- nitrophenoxy)-propane (EPNP) was increased in marmosets treated with phenobarbitone (2.6-fold) and rifampicin (2.6-fold), activity towards dichloromethane (DCM) was increased by 50% after treatment of marmosets with clofibric acid, and activity towards 1-chloro-2,4-dinitrobenzene (CDNB) was raised slightly (30-42% increases) after treatment with phenobarbitone, rifampicin or clofibric acid. Compared with humans, marmoset liver cytosol GST activity towards DCM was 18-fold higher, activity towards MC was 7 times higher and activity towards CDNB was 4 times higher. Further, EPNP activity was clearly detectable in marmoset liver cytosol samples, but was undetectable in human samples. Immunoreactive marmoset GST was partially purified by affinity chromatography using hexylglutathione-Sepharose and Orange A resin. The interaction of immunoreactive marmoset GST was similar to that found previously for rat and human GSTT1, suggesting that this protein is also a theta class GST. However, unlike rat GSTT1, the marmoset enzyme was not the major catalyst of EPNP conjugation. Instead, immunoreactivity was closely associated with activity towards MC. In conclusion, these results provide evidence for the presence of theta-class GST in the marmoset monkey orthologous to rGSTT1 and hGSTT1.

PCDD and PCDF concentrations in a traffic tunnel environment

In an effort to understand the fundamental aspects of air quality in traffic tunnel environments, field campaigns were conducted to measure polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and other important pollutants within two traffic tunnels in Nam San (NS) and Hong Ji (HJ) in Korea in 2009 and 2010. The mean concentrations of ∑PCDD/Fs (in fg/m(3)) at the two tunnel sites were 1270 (± 880) and 1200 (± 810), respectively. These values were moderately lower than those measured at a non-tunnel urban background site (1350 (± 780) fg/m(3))--selected as a reference in this study. In addition, seasonal patterns of dioxin concentrations were clearly evident at the traffic tunnels like the urban reference site, showing higher levels during the winter (and spring) than the summer (and fall). The observed seasonal variations were driven by changes in the concentrations of ∑PCDF congeners, while ∑PCDD concentrations showed little seasonality. The results of our study suggest that there is no significant difference in source characteristics between the two investigated tunnel sites and urban location, although the role of gasoline and diesel fueled vehicles are considered as the major source in determining the PCDDs and PCDF levels in a tunnel environment. However, given the relative increase in other important ambient pollutant (e.g. PM10) concentrations over ∑PCDD/Fs in tunnel air (compared to urban background air), the balance of sources in tunnels is clearly different from those in urban air overall.

Spatial distribution of selected persistent organic pollutants (POPs) in Australia's atmosphere

A nation-wide passive air sampling campaign recorded concentrations of persistent organic pollutants in Australia's atmosphere in 2012. XAD-based passive air samplers were deployed for one year at 15 sampling sites located in remote/background, agricultural and semi-urban and urban areas across the continent. Concentrations of 47 polychlorinated biphenyls ranged from 0.73 to 72 pg m-3 (median of 8.9 pg m-3) and were consistently higher at urban sites. The toxic equivalent concentration for the sum of 12 dioxin-like PCBs was low, ranging from below detection limits to 0.24 fg m-3 (median of 0.0086 fg m-3). Overall, the levels of polychlorinated biphenyls in Australia were among the lowest reported globally to date. Among the organochlorine pesticides, hexachlorobenzene had the highest (median of 41 pg m-3) and most uniform concentration (with a ratio between highest and lowest value [similar]5). Bushfires may be responsible for atmospheric hexachlorobenzene levels in Australia that exceeded Southern Hemispheric baseline levels by a factor of [similar]4. Organochlorine pesticide concentrations generally increased from remote/background and agricultural sites to urban sites, except for high concentrations of [small alpha]-endosulfan and DDTs at specific agricultural sites. Concentrations of heptachlor (0.47-210 pg m-3), dieldrin (ND-160 pg m-3) and trans- and cis-chlordanes (0.83-180 pg m-3, sum of) in Australian air were among the highest reported globally to date, whereas those of DDT and its metabolites (ND-160 pg m-3, sum of), [small alpha]-, [small beta]-, [gamma]- and [small delta]-hexachlorocyclohexane (ND-6.7 pg m-3, sum of) and [small alpha]-endosulfan (ND-27 pg m-3) were among the lowest.