Potential Impact on Standards for Toxic Air Contaminants

Since the Bhopal incident, the public has placed pressure on regulatory agencies to set community exposure limits for the dozens of chemicals that may be released by manufacturing facilities. More or less objective limits can be established for the vast majority of these chemicals through the use of risk assessment. However, each step of the risk assessment process (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization) contains a number of pitfalls that scientists need to avoid to ensure that valid limits are established. For example, in the hazard identification step there has been little discrimination among animal carcinogens with respect to mechanism of action or the epidemiology experience. In the dose-response portion, rarely is the range of “plausible” estimated risks presented. Physiologically based pharmacokinetic (PB-PK) models should be used to understand the difference between the tissue doses and the administered dose, as well as the difference in target tissue concentrations of the toxicant between rodents and humans. Biologically-based models like the Moolgavkar-Knudson-Venzon (MKV) should be developed and used, when appropriate. The exposure assessment step can be significantly improved by using more sensitive and specific sampling and analytical methods, more accurate exposure parameters, and computer models that can account for complex environmental factors. Whenever possible, model predictions of exposure and uptake should be validated by biological monitoring of exposed persons (urine, blood, adipose) or by field measurements of plants, soil, fish, air, or water. In each portion of an assessment, the weight of evidence approach should be used to identify the most defensible value. In the risk characterization, the best estimate of the potential risk as well as the highest plausible risk should be presented. Future assessments would be much improved if quantitative uncertainty analyses were conducted. Procedures are currently available for making future assessments. By correcting some of these shortcomings in how health risk assessments have been conducted, scientists and risk managers should be better able to identify scientifically appropriate ambient air standards and emission limits.     

The current practice of health risk assessment: potential impact on standards for toxic air contaminants

Since the Bhopal incident, the public has placed pressure on regulatory agencies to set community exposure limits for the dozens of chemicals that may be released by manufacturing facilities. More or less objective limits can be established for the vast majority of these chemicals through the use of risk assessment. However, each step of the risk assessment process (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization) contains a number of pitfalls that scientists need to avoid to ensure that valid limits are established. For example, in the hazard identification step there has been little discrimination among animal carcinogens with respect to mechanism of action or the epidemiology experience. In the dose-response portion, rarely is the range of "plausible" estimated risks presented. Physiologically based pharmacokinetic (PB-PK) models should be used to understand the difference between the tissue doses and the administered dose, as well as the difference in target tissue concentrations of the toxicant between rodents and humans. Biologically-based models like the Moolgavkar-Knudson-Venzon (MKV) should be developed and used, when appropriate. The exposure assessment step can be significantly improved by using more sensitive and specific sampling and analytical methods, more accurate exposure parameters, and computer models that can account for complex environmental factors. Whenever possible, model predictions of exposure and uptake should be validated by biological monitoring of exposed persons (urine, blood, adipose) or by field measurements of plants, soil, fish, air, or water. In each portion of an assessment, the weight of evidence approach should be used to identify the most defensible value. In the risk characterization, the best estimate of the potential risk as well as the highest plausible risk should be presented. Future assessments would be much improved if quantitative uncertainty analyses were conducted. Procedures are currently available for making future assessments. By correcting some of these shortcomings in how health risk assessments have been conducted, scientists and risk managers should be better able to identify scientifically appropriate ambient air standards and emission limits.     

Is the evaluation of “traditional” physicochemical parameters sufficient to explain the potential toxicity of the treated wastewater at sewage treatment plants?

Water scarcity is one of the most important environmental and public health problems of our century. Treated wastewater reuse seems to be the most attractive option for the enhancement of water resources. However, the lack of uniform guidelines at European and/or Mediterranean level leaves room for application of varying guidelines and regulations, usually not based on risk assessment towards humans and the environment. The benefits of complementing the physicochemical evaluation of wastewater with a biological one are demonstrated in the present study using Cyprus, a country with extended water reuse applications, as an example. Four organisms from different trophic levels were used for the biological assessment of the wastewater, namely, Pseudokirchneriella subcapitata, Daphnia magna, Artemia salina and Vibrio fischeri. The physicochemical assessment of wastewater based on “traditional” chemical parameters indicated that the quality of the wastewater complies with the limits set by the relevant national guidelines for disposal. The ecotoxicological assessment, however, indicated the presence of toxicity throughout the sampling periods and most importantly an increase of the toxicity of the treated wastewater during summer compared to winter. The resulting poor correlation between the physicochemical and biological assessments demonstrates that the two assessments are necessary and should be performed in parallel in order to be able to obtain concrete results on the overall quality of the treated effluent. Moreover, a hazard classification scheme for wastewater is proposed, which can enable the comparison of the data sets of the various parameters deriving from the biological assessment in a comprehensive way.     

化工项目环境影响评价要点

化工项目的环境影响评价应严格执行有关的法律、法规和导则,并结合行业特点执行特定的条例和规范。在其评价过程中应确保工程分析数据的可靠性和措施的可行性,对是否符合清洁生产进行详细阐述,针对事故风险进行评价并提出防范措施,最后对有毒废渣的处理提出要求。     

Quantifying risks of toxic chemicals to aquatic populations and ecosystems

The objectives of regulatory practice have evolved from eliminating all risks of pesticides and toxic chemicals to the environment to reducing risks to acceptable levels. This change in philosophy requires the development of methods for quantifying the risks of toxicant exposure to the exposed biota. Ecological risk assessment models that are comparable those used in human health risk assessment have been developed using methods drawn from ecotoxicology, ecology, statistics, and mathematical modeling. Initial applications have shown that the regulation of pesticides and toxic chemicals can be substantially improved through the use of ecological risk assessment.     

Evaluating the effectiveness of air quality regulations: A review of accountability studies and frameworks

Assessments of past environmental policies—termed accountability studies—contribute important information to the decision-making process used to review the efficacy of past policies, and subsequently aid in the development of effective new policies. These studies have used a variety of methods that have achieved varying levels of success at linking improvements in air quality and/or health to regulations. The Health Effects Institute defines the air pollution accountability framework as a chain of events that includes the regulation of interest, air quality, exposure/dose, and health outcomes, and suggests that accountability research should address impacts for each of these linkages. Early accountability studies investigated short-term, local regulatory actions (for example, coal use banned city-wide on a specific date or traffic pattern changes made for Olympic Games). Recent studies assessed regulations implemented over longer time and larger spatial scales. Studies on broader scales require accountability research methods that account for effects of confounding factors that increase over time and space. Improved estimates of appropriate baseline levels (sometimes termed “counterfactual”—the expected state in a scenario without an intervention) that account for confounders and uncertainties at each link in the accountability chain will help estimate causality with greater certainty. In the direct accountability framework, researchers link outcomes with regulations using statistical methods that bypass the link-by-link approach of classical accountability. Direct accountability results and methods complement the classical approach. New studies should take advantage of advanced planning for accountability studies, new data sources (such as satellite measurements), and new statistical methods. Evaluation of new methods and data sources is necessary to improve investigations of long-term regulations, and associated uncertainty should be accounted for at each link to provide a confidence estimate of air quality regulation effectiveness. The final step in any accountability is the comparison of results with the proposed benefits of an air quality policy.

Implications: The field of air pollution accountability continues to grow in importance to a number of stakeholders. Two frameworks, the classical accountability chain and direct accountability, have been used to estimate impacts of regulatory actions, and both require careful attention to confounders and uncertainties. Researchers should continue to develop and evaluate both methods as they investigate current and future air pollution regulations.     

Model selection and evaluation for risk assessment of dioxin-contaminated sites

The general European population has a total intake of dioxins and dioxin-like chemicals near the limit recommended by the European Union, making additional exposure above background levels undesirable. For populations living near dioxin-contaminated sites, additional exposure may occur by intake of locally produced food, inhalation of particles, dermal contact with soils, or other exposure pathways. Risk assessment tools are required to estimate risks associated with contaminated sites and to set priorities for site remediation. Here, we review several multimedia models that can be applied as tools to support risk assessment. We then present a strategy to select, apply, evaluate, and adapt a model to address a specific situation. The case study we consider is a risk assessment of generic background dioxin exposure in Sweden, and we compare the predictions with environmental observations and exposure data from Sweden. Arguments are presented for selecting the CalTOX model for this case study. We demonstrate the application, evaluation, and adaptation of the model and discuss the requirements for extending the analysis to conduct risk assessment for subpopulations living near dioxin-contaminated sites.     

Predicting Potential Sound Levels : A Case Study in an Urban Area

Allowable sound pressure levels for industrial, commercial and residential sources of noise are typically governed by state and/or local noise regulations. This paper presents a six-step methodology which was successfully applied by a supermarket in Massachusetts to secure state permission to build and operate a new 52,000 square foot store. This multiple step process included baseline noise monitoring, obtaining reference sound levels of the proposed rooftop refrigeration equipment, predicting future sound levels, and recommending soundlevel mitigation techniques. Post-construction monitoring at the store verified that actual worst-case sound levels agreed with predicted values.     

Paradigm lost, paradigm found: the re-emergence of hormesis as a fundamental dose response model in the toxicological sciences

This paper provides an assessment of the toxicological basis of the hormetic dose-response relationship including issues relating to its reproducibility, frequency, and generalizability across biological models, endpoints measured and chemical class/physical stressors and implications for risk assessment. The quantitative features of the hormetic dose response are described and placed within toxicological context that considers study design, temporal assessment, mechanism, and experimental model/population heterogeneity. Particular emphasis is placed on an historical evaluation of why the field of toxicology rejected hormesis in favor of dose response models such as the threshold model for assessing non-carcinogens and linear no threshold (LNT) models for assessing carcinogens. The paper argues that such decisions were principally based on complex historical factors that emerged from the intense and protracted conflict between what is now called traditional medicine and homeopathy and the overly dominating influence of regulatory agencies on the toxicological intellectual agenda. Such regulatory agency influence emphasized hazard/risk assessment goals such as the derivation of no observed adverse effect levels (NOAELs) and the lowest observed adverse effect levels (LOAELs) which were derived principally from high dose studies using few doses, a feature which restricted perceptions and distorted judgments of several generations of toxicologists concerning the nature of the dose-response continuum. Such historical and technical blind spots lead the field of toxicology to not only reject an established dose-response model (hormesis), but also the model that was more common and fundamental than those that the field accepted.     

Levels and risk assessment of chemical contaminants in byproducts for animal feed in Denmark

With aim to provide information on chemical contaminants in byproducts in animal feed, the data from an official control by the Danish Plant Directorate during 1998–2009, were reviewed and several samples of citrus pulp and dried distillers grains with solubles (DDGS) were additionally collected for analysis and risk assessment. The levels of contaminants in the samples from the official control were below maximum limits from EU regulations with only a few exceptions in the following groups; dioxins and dioxin-like polychlorobiphenyls (PCBs) in fish-containing byproducts and dioxins in vegetable and animal fat, hydrogen cyanide in linseed, and cadmium in sunflowers. The levels of pesticides and mycotoxins in the additionally collected samples were below maximum limits. Enniatin B (ENN B) was present in all DDGS samples. The hypothetical cases of carry-over of contamination from these byproducts were designed assuming total absorption and accumulation of the ingested contaminant in meat and milk and high exposure (a byproduct formed 15–20% of the feed ration depending on the species). The risk assessment was refined based on literature data on metabolism in relevant animal species. Risk assessment of contaminants in byproducts is generally based on a worst-case approach, as data on carry-over of a contaminant are sparse. This may lead to erroneous estimation of health hazards. The presence of ENN B in all samples of DDGS indicates that potential impact of this emerging mycotoxin on feed and food safety deserves attention. A challenge for the future is to fill up gaps in toxicological databases and improve models for carry-over of contaminants.     

Specific issues in health risk assessment of endocrine disrupting chemicals and international activities.

Specific issues in health risk assessment of EDCs and correlated international activities thereof are discussed. Risk characterization is a synthesis of all information including hazard assessment, dose-response relationship, and exposure information to identify clearly the strengths and weaknesses of the database, the criteria applied to evaluation and validation of all aspects of methodology, and the conclusions reached from the review of scientific information. In the case of EDCs, new models need to be developed taking into account possible new kinds of information, e.g., effects of EDCs on gene activation in response to hormonal challenge or effects on receptor expression. Such models should also account for homeostatic adaptive responses and consider the possibility of having windows of exposure for given effects. Work to compile and harmonize the definitions and terms appropriate to endocrine disruption will be conducted within the joint IPCS/OECD project on harmonization of risk/hazard assessment terminology reviews. The ICPS is the process of preparing a "State of the Science" report, and is implementing a global inventory of ongoing research on ECDs.     

Proposals to overcome limitations in the EU chemical risk assessment scheme

The notification of new chemicals in the European Union requires a risk assessment. A Technical Guidance Document (TGD) was prepared for assistance. The TGD proposes QSARs, regressions and models from various sources. Each method has its own range of applicability and its own restrictions. Regressions used in the assessment of indirect human exposure have a common regression range from log K(OW), 3.0-4.6. Most models are compartment models, which do not consider a spatial distribution of the chemical, and were originally developed for non-dissociating, lipophilic persistent chemicals with measurable vapor pressure. Taking this into account, the TGD is only applicable for a minority of chemical classes. Dissociating compounds, ions, polar and very non-polar compounds do not belong to them. The effect of mixtures cannot be considered, except for hydrocarbons. Using the example of plant uptake, it is shown that in certain cases uptake is underestimated by the model due to processes not considered. This may lead to a wrong security in risk assessment. To overcome these limitations, a set of alternative models with different application ranges should be developed. When no applicable method is available, it might be better not to use a model at all instead of an inadequate model, and look for other sources of information.     

Evaluation of PNEC values: extrapolation from Microtox, algae, daphnid, and fish data to HC5

In order to evaluate the risk to the environment from long term exposure of any discharged substance, toxicity thresholds are estimated, and particularly the Predicted No Effect Concentration (PNEC). This concentration can be estimated by the classic assessment factor approach or by statistical methods. These are more scientifically sound but they require several (at least 5-6) chronic ecotoxicity data, implying greater cost and time. New extrapolation methods derived from the statistical concept but requiring less data have been studied. Results show that methods based on chronic data are more reliable than methods based on acute data but the improvement is quite small. Considering the costs of chronic tests compared to acute tests, approaches based on acute data are an attractive alternative. A simple regression on the mean of the acute data gives the best results.     

Biochemical biomarkers in environmental studies—lessons learnt from enzymes catalase,glutathione <Emphasis Type="Italic">S</Emphasis>-transferase and cholinesterase in two crustacean species

Background, aim and scope  

For reliable environmental risk assessment of pollutants, knowledge on the effects at different levels of biological organisation is needed. During the early days of biomarker research in environmental studies approximately two decades ago, biochemical biomarkers were considered as the most promising tool for such purposes. Among these, three enzymes have often been studied: catalase (CAT), glutathione S-transferase (GST) and cholinesterase (ChE). However, despite their intensive research, their measurements in invertebrates have not been commonly applied in environmental risk assessment (ERA) or for regulatory purposes.     

Bound residues: environmental solution or future problem?

The paper examines the issue of bound residues from the viewpoint of the risk assessment procedures employed for environmental protection. It considers, on one hand, the evidence that such residues are so tightly bound to soil organic matter as to be essentially unavailable; and on the other, the perspective that we should not be loading up the environment with compounds whose future behaviour and release we cannot predict. Existing knowledge of the mechanisms by which residues bind to soil organic matter suggests that release will be closely dependent on soil organic matter breakdown. Simple models of organic matter turnover suggest that the release following single applications of individual compounds will be very slow; but the significance of releases following repeated application over many years of a number of compounds needs to be investigated further. Applying environmental risk assessment techniques is complicated by the difficulty in identifying parent molecules and potential metabolites in the bound residue fraction. The paper concludes that for single additions of individual compounds, bound residues probably do represent an environmental solution. But the long-term significance of bound residues formed from multiple additions of a number of compounds is less clear. The paper recommends that future work should emphasise the biological significance of such residues and their release.     

Regulation (EC) No. 1107/2009 and upcoming challenges for exposure assessment of plant protection products--Harmonisation or national modelling approaches?

In the new European Pesticide Regulation (EC) No. 1107/2009, the harmonisation of approaches for estimation of the environmental exposure of pesticides is considered a major goal. Several member states currently require their own models for the calculation of predicted environmental concentrations (PEC) in surface water. The variety of methods makes risk evaluations rather time-consuming for both notifiers and evaluating authorities. In the present study we compare surface water concentrations of 19 compounds using EU and country-specific models and risk assessment approaches to evaluate to which extent the resulting estimated exposure concentrations differ. Our results show that EU and country specific approaches and the resulting surface water concentrations differ considerably regarding basic model assumptions and assessment methods. The results indicate that the aimed harmonisation of risk assessment approaches within the EU will be difficult based on current models. New scenarios may help to achieve a harmonisation taking country-specific features into account.     

Ecotoxicological research and related legislation in Serbia

Introduction

Several hot spots of severe freshwater pollution and sediment contamination (mostly heavy metals, polyaromatic hydrocarbons and polychlorinated biphenyls) have been identified in Serbia as the consequence of outdated environmental legislation, negligible amounts of properly treated waste waters and accidental spills.

Discussion

Since ecotoxicological methods have never been incorporated into risk assessment procedures, mandatory effluent discharge or ambient water monitoring programmes, ecotoxicological research, based on bioaccumulation studies, conventional ecotoxicological tests and, recently, biomarkers of exposure and effect have been restricted to independent small- to medium-scale studies, conducted, basically, to confirm, underline or oppose the results of chemical-based monitoring and to lament on inadequate environmental regulations/policy and management practice. Although hot and unresolved ecotoxicological problems still remain beyond the reach of ecotoxicological research currently conducted in Serbia, or are tackled only sporadically, it is to be expected that on-going research and institutional capacity building should, hopefully, increase the competence and competitiveness of scientific community and speed up the process of harmonisation of national environmental legislation and policy with European Union.

     

Legal aspects of pesticides and toxic substances testing requirements

Abstract

The United States Environmental Protection Agency administers several laws and progrms through which it reviews the hazard potential of pesticides and other toxic substances which may present a risk to human health or the environment. The Agency's ability to assess hazard as required by law depends in part on test data developed through testing standards in Agency regulations. In reviewing the Agency's actions in this regard, the courts emphasize the importance of reasoned regulatory decisions. The legal requirements to assess risk and provide reasoned decisions in this regard establish the legal importance of testing guidelines and test data, and indicate that sound test methodology is as important legally as it is scientifically.     

我国环境介质中多环芳烃的分布及其生态风险

持久性有机污染物多环芳烃(PAHs)在我国环境介质中广泛分布,美国EPA规定的16种.优先控制多环芳烃大多在我国大气、水体、沉积物、土壤和生物体内检出.总结了我国环境介质中PAHs污染水平及特点,分析了其存在的环境风险.我国大气中PAHs污染较重,尤其是北方.水体已普遍受PAHs污染,其中部分水体污染严重;沉积物多环芳烃污染大多处于低生态风险水平,但沉积记录研究表明有越来越严重的趋势.我国土壤和生物体PAHs含量较低,污染生态风险较小.部分区域蔬菜中PAHs含量较高,存在不可忽视的生态风险.     

Reducing Risk in Hazardous Waste Management

Over the past several years, the Environmental Protection Agency has attempted to institutionalize an approach to its activities that is characterized by an active attempt to separate risk assessment from risk management activities. This approach, while not new in concept, has only been evolving at EPA for about four years. The Office of Research and Development, or ORD, has organized its research planning activities around this risk assessment-risk management concept. In order for the approach to succeed, it is necessary to develop the data and methodology necessary to undertake risk assessments both in the area of human health and ecology, and to develop methods to reduce those risks. Accordingly, we have organized our research planning into four major areas: Human Health Risk, Environmental or Ecological Risk, Exposure Assessment, and Risk Reduction. What I would like to do is outline briefly the breadth and diversity of EPA’s research program and the Agency’s research needs.