[Quantitative risk assessment of occupational exposure to PCDD/Fs in the waste incineration industry].

Objective: To analyze the level of PCDD/Fs exposure of occupational workers in the waste incineration industry and explore the risk of occupational exposure. Methods: In September 2021, literature on environmental PCDD/Fs exposure in waste incineration plants published from the establishment of the database to February 10, 2021 was retrieved from CNKI database. A total of 1365 literatures were retrieved, and 7 met the criteria for inclusion. The US Environmental Protection Agency (EPA) inhalation risk model was used to assess and analyze carcinogenic and non-carcinogenic risks of PCDD/Fs exposure among occupational workers in the waste incineration industry. Results: A total of 86 sampling sites were included in incineration plants in 7 regions. The study of Wuhan area showed that the concentration of working environment near the waste incinerator in the same factory was the highest, followed by the rest and office area in the factory. The concentration of PCDD/Fs in waste incinerators was the highest in Southwest China (4880.00-24880.00 pg TEQ/m(3)), and the lowest in Shenzhen (0.02-0.44 pg TEQ/m(3)). According to the cancer risk assessment, with the increase of exposure years, the risk of cancer increased. The highest risk of cancer was found in the waste incineration plants in Southwest China. When the exposure period was 1 year, the risk was moderate (22.40×10(-6)-114.20×10(-6)). When the exposure time was more than 5 years, the risk of cancer was high. In Jinan, workers working near the incinerator had a moderate risk of cancer after five years of exposure. In Zhejiang, workers were at medium risk of cancer after exposure for more than 20 years. Workers in Wuhan, Shanghai, Zhejiang Province, Shenzhen and the Pearl River Delta were still at low risk of cancer after 40 years of occupational exposure. HQ>1 of workers working near the waste incinerators in Jinan, Zhejiang Province and Southwest China, and the qualitative evaluation results showed that the non-carcinogenic risk was unacceptable. Conclusion: There are great differences in PCDD/Fs of occupational exposure in waste incineration industry, and the occupational exposure exceeding the occupational exposure limit has higher carcinogenic and non carcinogenic risks.

Quantifying and Adjusting for Disease Misclassification Due to Loss to Follow-Up in Historical Cohort Mortality Studies.

The purpose of this analysis was to quantify and adjust for disease misclassification from loss to follow-up in a historical cohort mortality study of workers where exposure was categorized as a multi-level variable. Disease classification parameters were defined using 2008 mortality data for the New Zealand population and the proportions of known deaths observed for the cohort. The probability distributions for each classification parameter were constructed to account for potential differences in mortality due to exposure status, gender, and ethnicity. Probabilistic uncertainty analysis (bias analysis), which uses Monte Carlo techniques, was then used to sample each parameter distribution 50,000 times, calculating adjusted odds ratios (ORDM-LTF) that compared the mortality of workers with the highest cumulative exposure to those that were considered never-exposed. The geometric mean ORDM-LTF ranged between 1.65 (certainty interval (CI): 0.50-3.88) and 3.33 (CI: 1.21-10.48), and the geometric mean of the disease-misclassification error factor (εDM-LTF), which is the ratio of the observed odds ratio to the adjusted odds ratio, had a range of 0.91 (CI: 0.29-2.52) to 1.85 (CI: 0.78-6.07). Only when workers in the highest exposure category were more likely than those never-exposed to be misclassified as non-cases did the ORDM-LTF frequency distributions shift further away from the null. The application of uncertainty analysis to historical cohort mortality studies with multi-level exposures can provide valuable insight into the magnitude and direction of study error resulting from losses to follow-up.

A review of environmental fate, body burdens, and human health risk assessment of PCDD/Fs at two typical electronic waste recycling sites in China.

This paper reviews the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in different environmental media, human body burdens and health risk assessment results at e-waste recycling sites in China. To provide an indication of the seriousness of the pollution levels in the e-waste recycling sites in China, the data are compared with guidelines and available existing data for other areas. The comparison clearly shows that PCDD/Fs derived from the recycling processes lead to serious pollution in different environmental compartments (such as air, soil, sediment, dust and biota) and heavy body burdens. Of all kinds of e-waste recycling operations, open burning of e-waste and acid leaching activities are identified as the major sources of PCDD/Fs. Deriving from the published data, the estimated total exposure doses via dietary intake, inhalation, soil/dust ingestion and dermal contact are calculated for adults, children and breast-fed infants living in two major e-waste processing locations in China. The values ranged from 5.59 to 105.16 pg WHO-TEQ/kg bw/day, exceeding the tolerable daily intakes recommended by the WHO (1-4 pg WHO-TEQ/kg bw/day). Dietary intake is the most important exposure route for infants, children and adults living in these sites, contributing 60-99% of the total intakes. Inhalation is the second major exposure route, accounted for 12-30% of the total exposure doses of children and adults. In order to protect the environment and human health, there is an urgent need to control and monitor the informal e-waste recycling operations. Knowledge gaps, such as comprehensive dietary exposure data, epidemiological and clinical studies, body burdens of infants and children, and kinetics about PCDD/Fs partitions among different human tissues should be addressed.

Science versus policy in establishing equitable Agent Orange disability compensation policy.

This article makes the case that current Agent Orange compensation policy for Vietnam War veterans is based neither wholly upon scientific findings about Agent Orange health effects nor on pure public health policy considerations. Rather, it is the logical culmination of decades of experience among policy makers and public health scientists trying to establish clear-cut, equitable, and scientifically defensible compensation policy in the face of limited relevant science and poor or nonexistent exposure data-all within the broader context of Veterans Affairs disability compensation policies, and a deep-seated commitment to support the men and women who served their country during the Vietnam War. Finally, attempts to update current policy will benefit from an understanding of this background.

Presumptive service connection for disease associated with exposure to certain herbicide agents: AL amyloidosis. Final rule.

This document amends the Department of Veterans Affairs (VA) adjudication regulations concerning presumptive service connection for a certain disease based on the most recent National Academy of Sciences (NAS) Institute of Medicine committee report, "Veterans and Agent Orange: Update 2006" (Update 2006). This amendment is necessary to implement a decision of the Secretary of Veterans Affairs that there is a positive association between exposure to herbicides used in the Republic of Vietnam during the Vietnam era and the subsequent development of AL amyloidosis. The intended effect of this amendment is to establish presumptive service connection for AL amyloidosis based on herbicide exposure.

The legacy of Agent Orange: empirical evidence from central Vietnam.

This paper seeks to provide a socio-economic impact assessment for Vietnamese victims of the principal US military herbicide, Agent Orange, used during the Vietnam War in the period 1961-71. The study is based on a field survey of 30 affected and 30 unaffected households in Quang Tri province. With this assessment, the paper attempts to address the broader issues of compensation currently available to victims. The coverage and composition of current benefits are deemed inadequate as an effective redress. In view of this, revision of current compensation, the mobilization of an international donor fund and spurred non-governmental support is strongly recommended.

Cost-benefit analysis as a tool for decision making in environmental projects. Application to a reduction of dioxin emissions in Tarragona Province, Spain.

BACKGROUND, AIM AND SCOPE: The Damage-Function method is an efficient tool recently used in decision-making processes concerning environmental management. It is based on finding the relation between the origin of an environmental charge, and its impact on human health and the environment. The aim of the present investigation was to assess the positive impacts, also called benefits, of changes in environmental quality, and the economic viability of an industrial project on reduction of PCDD/F emissions. It has been developed with monetary criteria of two worldwide ambits: USA and European-Union countries. METHODS: The current study is a continuation of a previous investigation in which Substance Flow Analysis and Control Analysis Techniques were used to identify and to analyze all main flow values of PCDD/Fs inside the system of Tarragona Province (Spain). In the present study, Cost-Benefit Analysis (CBA) has been employed. The benefits derived from a minimization in the incidence of cancer due to a reduction in the emission of PCDD/Fs have been evaluated considering the value of a statistically saved life (VSL). Statistical analysis about uncertainty has also been incorporated. Here, the Monte Carlo simulation technique has been used. RESULTS: It is shown that CBS results depend firstly on the kind of VSL used. In fact, the differences between the decisions as a result of applying monetary criteria in USA and EU can be explained by differences between VSL values. CONCLUSION AND RECOMMENDATION: It is concluded that, for prices estimated in Euros, the emission cleaning project in the industrial plant is not feasible under any circumstance. However, although CBA seems to be a good analytical method, the final decision corresponds to the managers, who must weigh up not only the monetary criteria, but factors such as social questions.

Health risk assessment of PCDD/PCDF exposure for the population living in the vicinity of a municipal waste incinerator.

Emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) by municipal solid waste (MSW) incinerators cause concern to the populations living in the vicinity of these facilities. In this study, the health risks of PCDD/F exposure were assessed for adults and children living 500 and 1,000 m from the MSW incinerator. A comparative analysis was performed before (1998) and after (2000) pronounced decreases in PCDD/F air emissions from the stack were noted as a consequence of technical improvements in the facility. At 500 m, total environmental exposure to PCDD/Fs diminished from 5.102 x 10(-5) to 1.271 x 10(-5) ng I-TEQ/kg/day for adults, and from 8.131 x 10(-5) to 2.656 x 10(-5) ng I-TEQ/kg/day for children, which means a reduction of 75.1% for adults and 67.3% for children between 1998 and 2000. At 1,000 m, total environmental PCDD/F exposure diminished from 4.087 x 10(-5) ng I-TEQ/kg/day in 1998 to 0.995 x 10(-5) ng I-TEQ/kg/day in 2000 and from 6.294 x 10(-5) ng I-TEQ/kg/day in 1998 to 1.983 x 10(-5) ng I-TEQ/kg/day in 2000 for adults and children, respectively. However, these reductions are almost imperceptible compared with the contribution of dietary intake of PCDD/F to total exposure to these contaminants. The present results corroborate that for MSW incinerators with modern technologies, human PCDD/F exposure is mainly due to background contamination.

Human exposure to dioxins and furans: application of the substance flow analysis to health risk assessment.

Substance Flow Analysis (SFA) is an important instrument that allows for the undertaking of environmental management for a specific contaminant. 'Control Analysis' is a tool that assesses the effect on a target flow of changes in flows forming part of a control basis set. The purpose of the present study was to perform a modeling of the annual PCDD/F flows in Tarragona Province and to apply the model for human health risk assessment. The validation of the model has been evaluated by comparing estimated fluxes with experimental values. Eleven subsystems, as well as a set of 88 flows of the system in Tarragona Province were considered. The total PCDD/F accumulation in Tarragona Province was between 62.6 and 159.5 g I-TEQ/y. Accumulation in sediments (27.9-74.6 g I-TEQ/y) and soils (35.0-80.8 g I-TEQ/y) are the two principal modes of deposition. Estimated flow in human adipose tissue means a mean intake of PCDD/F (via ingestion and inhalation) of 243 pg I-TEQ/person/day. The food chain pathway accounts for 99% of the total daily intake. As a result of the simulation, a 100% decrease in industrial emissions would cause a 1.7% reduction in the PCDD/F accumulation in humans. In turn, a 100% reduction of PCDD/Fs in the industrial waste waters would cause only an insignificant 0.1% decrease in the accumulation of PCDD/Fs in humans.

Congener-distribution patterns and risk assessment of polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in Korean human milk.

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) were analyzed by high-resolution gas chromatography/high-resolution mass spectrometry in human milk samples from an urban and an industrial area in Korea. All PCB congeners were analyzed to characterize the congener distribution as well as to evaluate the toxic equivalent quotient (TEQ) values and the total concentration. In homologue distributions of PCBs, two distinct patterns were found. The mean concentrations of PCDD/Fs and PCBs were 15.13 and 5.64 TEQ pg/g fat (based on WHO TEF, 1997), respectively. The contamination in Korean human milk is comparable to that found in other countries. From these results a daily intake of 60 TEQ pg/kg/day for an infant was estimated. The assumptions were that the infant breast feeds for 1 year, has an average body weight of 10 kg during this period, and ingests 800 g/day of human milk containing a mean concentration of 20.84 TEQ (PCDD/Fs) pg/g fat (based on primipara mothers).

Changes to the TEF schemes can have significant impacts on regulation and management of PCDD/F and PCB.

The changes recommended by the World Health Organisation (WHO) to the toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) and the recommendation to extend both the TEF scheme and the tolerable daily intake (TDI) to include "dioxin-like" PCB congeners have significant implications for regulators who have relied heavily on the International TEF (I-TEF) scheme in setting and monitoring limits and exposure to these compounds. This paper examines example data sets of sources, environmental concentrations, food and exposure to indicate likely changes in calculated toxic equivalent (TEQ) due to the recommended changes to TEFs. Many published data sets available do not provide congener specific data for PCDD/F which limits the ability to recalculate TEQs. There are even fewer congener specific data published to enable calculation of TEQs for the dioxin-like PCBs. In general TEQs calculated using the WHO scheme for emissions to air were found to show small increases (in the order of 1-10%) in comparison to the I-TEQ (for PCDD/F), some sludge samples showed substantial decreases (up to 70%). Levels in food and calculations of exposure showed that the change to TEFs for PCDD/F increased calculated exposure by 10-20% while the change to PCB TEFs decreased calculated TEQ attributable to PCB by 0-10%. The effects of including PCB in the overall TEQ and the changes to TEFs for PCDD/F substantially increase calculated TEQ exposure. Congener specific data should be presented to allow calculation of desired TEQ and the impact of the changes on emission limits, regulations on sludge use and environmental quality standards should all be carefully considered. The absence of data on emissions of dioxin-like PCB means that it is not possible to estimate with any certainty the impact on overall TEQ emissions of including the nominated PCB. Given the potential for confusion with the proliferation of TEFs and the extension to include both PCDD/F and PCB in the calculation of TEQs it is important that great care is taken to clearly express which compounds are included and which TEF scheme has been applied in each case.

Developing scientific and policy methods that support precautionary action in the face of uncertainty--the Institute of Medicine Committee on Agent Orange.

To be precautionary, decisions must be made to prevent the impacts of potentially harmful activities even though the nature and magnitude of harm have not been proven scientifically. The Institute of Medicine's Committee on the Health Effects in Vietnam Veterans of Exposures to Herbicides provides a novel example of science and policy structures that support precautionary action in the face of uncertainty. What makes this example unique is the clear set of precautionary decision rules that lowered the standard for evidence, which formed the basis for policy. These rules, established by Congress, strongly influenced the way scientific information was weighed and the subsequent compensation decisions. They encouraged committee members to think outside the confines of their disciplines and develop new tools and methods to fit their unique mandate. The result was a methodology, supported by strong institutional structures, that allowed scientists to discuss the evidence as a whole, reach decisions as a group, and clarify uncertainties.

The use of Monte-Carlo simulation techniques for risk assessment: study of a municipal waste incinerator.

The incremental lifetime risks due to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) for the residents living in the surroundings of a municipal solid waste incinerator (MSWI) have been assessed. Two different pathways of exposure to PCDD/Fs, ingestion through the diet and exposure from MSWI emissions, were compared. Monte-Carlo simulations were carried out to obtain variability and uncertainty propagation The joint analysis of uncertainty and variability included a sensitivity analysis that identified the contribution to variance by different inputs. In general terms, PCDD/F ingestion through the diet contributed with more than 99% of the total risk, whereas direct exposition to PCDD/F emissions from the MSWI was less than 1% The results show that the median (50% percentile) of non-carcinogenic risk due to PCDD/Fs in the population living in the surroundings of the MSWI was 0.72 and the ratio of the 95th percentile and fifth percentile was about 2. With respect to the total carcinogenic risk, the median increment in individual lifetime was 7.90 x 10(-5) while the ratio between the 95th percentile and the fifth percentile was about 1.5. In this analysis, a sequential structural decomposition of the relationships between the input variables has been used to partition the variance in the output (risk) in order to identify the most influential contributors to overall variance among them.

Public health assessment of hexachlorobenzene.

Recently, hexachlorobenzene (HCB) was proposed for inclusion in the system of toxicity equivalency factors (TEFs) currently used for dioxin-like compounds. In this paper, we explore the practical implications of the proposition to the Agency for Toxic Substances and Disease Registry (ATSDR) programs by comparing respective health guidance values for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and HCB (expressed as total toxicity equivalents [TEQs]), reviewing possible interactions between HCB and dioxin-like chemicals, and by providing information on actual co-existence of HCB and dioxin-like chemicals at hazardous waste sites. We found a good correlation between the TEF-adjusted oral exposure guidance values for HCB and guidance values for TCDD. The combination of HCB and other dioxin-like compounds was not found in soil, air, or water media at hazardous waste sites. Based on this fact, it is not necessary to include HCB in the total TEQ count at hazardous waste sites at this time.

Impact of chemical warfare with agent orange on women's reproductive lives in Vietnam: a pilot study.

During the American war in Vietnam, huge quantities of the highly toxic herbicide dioxin ('Agent Orange'), were sprayed over large areas of central and south Vietnam. In addition to polluting the environment and causing cancers and other diseases in those directly exposed to it, dioxin has caused high rates of pregnancy loss, congenital birth defects and other health problems in their children. This paper reports the findings of a pilot study in the year 2000 among 30 Vietnamese women whose husbands and/or who themselves were exposed to Agent Orange. The aim was to develop research in order to explore the impact of chemical warfare on people's lives. Using the reproductive lifeline and semi-structured interviews, information was gathered on both partners' periods of exposure to Agent Orange, pregnancy outcomes, perceived health problems of children and experiences of living with handicapped children. The women had had a high number of miscarriages and premature births. About two-thirds of their children had congenital malformations or developed disabilities within the first years of life. Most of the families were poor, aggravated by impaired health in the men, the burden of caring for disabled children, and feelings of guilt and inferiority. The plight of 'Agent Orange families' is special and should be placed in its historical and political context.

Human risk assessment and TEFs.

The concept of toxic equivalency factors (TEFs) has been developed to facilitate risk assessment and regulatory control of exposure to complex PCDD, PCDF and PCB mixtures. Recently the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly re-evaluated the TEFs of PCDDs, PCDFs and dioxin-like PCBs for mammals and derived consensus TEFs for birds and fish (Stockholm, 1997). From a mechanistic point of view it can be concluded that, although the quantitative response will vary depending on the congener involved, the occurrence of a common mechanism (binding to the Ah receptor) legitimates the use of the TEF concept across species. But there also is criticism regarding the TEF concept. Pharmacokinetic differences between species can significantly influence the TEF value, and uncertainties due to additive or non-additive interactions, to differences in species responsiveness and to differences in the shape of the dose-response curve might hamper the derivation of consensus TEF values. In this context it should be noted, however, that using TCDD alone, as the only measure of exposure to dioxin-like PCDDs, PCDFs and PCBs, would severely underestimate the risk from exposure to these compounds. Therefore, it can be concluded that, for pragmatic reasons, the TEF concept remains the most feasible approach for risk assessment purposes, in spite of the uncertainties associated with its use.