Implications of research on endocrine disruption for the environmental risk assessment, regulation and monitoring of chemicals in the European Union

We assess the implications which research on endocrine disrupting chemicals (EDCs) has for the regulation of synthetic substances and for the protection of the environment, particularly under the forthcoming European Union (EU) REACH legislation. EDCs present regulatory problems inter alia because they can act additively at concentrations which are individually harmless, and they may have non-classical dose (concentration)-response relationships at low exposure levels. Furthermore, current in vivo testing routines were not specifically designed to assess the endocrine disrupting properties of chemicals, whilst in silico and in vitro methods have only limited applicability and availability for this purpose. We need to ensure that the assessment approaches specified in the draft REACH legislation and Technical Guidance are able to evaluate EDCs efficiently. However, it must also be recognised that environmental monitoring procedures in Europe will need to be improved to detect EDCs that have evaded identification, and where appropriate, control, under REACH.     

Environmental risk assessment of existing chemicals

Most of the existing chemicals of high priority have been released into the environment for many years. Risk assessments for existing chemicals are now conducted within the framework of the German Existing Chemicals Program and by the EC Regulation on Existing Substances. The environmental assessment of a chemical involves:

1. exposure assessment leading to the derivation of a predicted environmental concentration (PEC) of a chemical from releases due to its production, processing, use, and disposal. The calculation of a PEC takes into account the dispersion of a chemical into different environmental compartments, elimination and dilution processes, as well as degradation. Monitoring data are also considered.
2. effects assessment. Data obtained from acute or long-term toxicity tests are used for extrapolation on environmental conditions. In order to calculate the concentration with expectedly no adverse effect on organisms (Predicted No Effect Concentration, PNEC) the effect values are divided by an assessment factor. This assessment factor depends on the quantity and quality of toxicity data available.

In the last step of the initial risk assessment, the measured or estimated PEC is compared with the PNEC. This “risk characterization” is conducted for each compartment separately (water, sediment, soil, and atmosphere). In case PEC > PNEC an attempt should be made to revise data of exposure and/or effects to conduct a refined risk characterization. In case PEC is again larger than PNEC risk reduction measures have to be considered.     

Evaluation of an ecosystem model in ecological risk assessment of chemicals

We used a Lake Suwa version of Comprehensive Aquatic Systems Model (CASM_SUWA) to demonstrate the risk estimation of 10 different chemicals and examined the applicability and reliability of the model in ecological risk assessment by qualitatively and quantitatively comparing with the results of studies on multiple species using mesocosm tests. The qualitative comparison of the model results with those of the reported mesocosm tests indicated that some evidence observed in mesocosm studies supported the indirect effects predicted from simulation using the model. The comparison of the concentration levels at which 20% biomass reduction (BR20) in the most sensitive population estimated from the model with the no-observed effect concentration values derived from multiple species mesocosm tests (MS-NOEC) suggested that both data were related to each other and the model can be used to help in the determination of an ecological acceptable level of chemicals in aquatic environments. The analysis of the potential of indirect effects of a chemical for fish population indicated that the magnitude of the potential of indirect effects was quantified based on the ratio of BR50 to LC50 for fish population.     

浅谈风险评价在有毒化学品管理中的作用

本文简单介绍了有毒化学品风险评价和风险管理的基本过程和方法以及它们之间的关系。作为实例 ,对某市某主要河道的污染物进行了监测、分析和计算 ,确定了主要有害污染物。取得的数据为环境管理部门采取控制措施提供了科学依据     

A screening method for preliminary assessment of risk to groundwater from land-applied chemicals

A simple mathematical model for initial screening is presented that can aid in evaluating the relative risk to groundwater from applying nonpolar synthetic organic chemicals to soil. The basic premise is that the magnitude of the quotient of the chemical concentration of the water entering the aquifer and the maximum allowable concentration (as established by EPA or Health Departments) represents the health risk of a chemical. The chemical concentration of the soil water is estimated based on conservative, simplifying assumptions and requires only readily available data such as: basic soil properties (organic matter and saturated hydraulic conductivity), organic chemical properties (octanol-water partition coefficient and degradation rate) and environmental factors (recharge rate and depth to groundwater).The methodology was applied to assess the relative risk of organic chemicals in municipal sewage sludge and pesticides applied to agricultural land. The results are realistic.     

Ecological risk assessment of pollutant chemicals: extinction risk based on population-level effects

The extinction probability is one of the most useful endpoints that are utilized in conservation biology. A parallel approach is advocated for the ecological risk assessment of chemical pollutants. The presented framework estimates extinction probability induced by pollutant chemicals in order to evaluate ecological hazards of pollution, and is applicable to any biological community (aquatic or terrestrial). The analytical framework, which is based on stochastic population dynamics theory, is briefly explained. The extinction risk estimation is feasible if ecotoxicological data concerning pollutant effects on population growth rate of organisms (the intrinsic rate of natural increase), and if environmental exposure concentration is provided. Tentative risk estimation was made for some agrochemicals and surfactants on zooplankton populations (Daphnia) as target organisms.     

Uncertainties and data needs in risk assessment of three commercial polybrominated diphenyl ethers: probabilistic exposure analysis and comparison with European Commission results

Some environmental monitoring programs have reported increasing levels of certain polybrominated diphenyl ether (PBDE) isomers in aquatic biota and in human breast milk. The commercial PBDE products are known as penta-, octa-, and deca-brominated diphenyl ethers (PeBDE, OBDE and DBDE, respectively). Aside from the current European Commission's risk assessment initiative and efforts underway in Sweden, Canada and elsewhere to evaluate environmental levels, little is understood about sources of exposure and risks to humans. In this study, a multi-pathway human health risk assessment was performed to predict theoretical chronic daily intakes (CDIs) of PeBDE, OBDE, and DBDE by five different age groups: 0-2, 2-6, 6-12, 12-18, and 18-70 years. Sources of exposure included air, drinking water, consumption of fish, vegetables, meat and dairy products, and ingestion of breast milk by infants. In addition to a deterministic analysis, the risk assessment included a probabilistic analysis to derive the probability density functions describing the range of plausible exposures associated with eight different pathways, as well as aggregate lifetime exposures for each age group. The results were compared to CDI point estimates calculated by the European Chemicals Bureau as part of the European Commission's Existing Substances Programme. The major sources of uncertainties are discussed, including environmental sources, levels in different environmental compartments, toxicity, and human exposure. This paper also discusses the limitations in the current state-of-the-science and provides recommendations for improving the scientific relevance and accuracy of future environmental risk assessments of PBDEs.     

Using a probabilistic approach in an ecological risk assessment simulation tool: test case for depleted uranium (DU)

A probabilistic approach was applied in an ecological risk assessment (ERA) to characterize risk and address uncertainty employing Monte Carlo simulations for assessing parameter and risk probabilistic distributions. This simulation tool (ERA) includes a Window's based interface, an interactive and modifiable database management system (DBMS) that addresses a food web at trophic levels, and a comprehensive evaluation of exposure pathways. To illustrate this model, ecological risks from depleted uranium (DU) exposure at the US Army Yuma Proving Ground (YPG) and Aberdeen Proving Ground (APG) were assessed and characterized. Probabilistic distributions showed that at YPG, a reduction in plant root weight is considered likely to occur (98% likelihood) from exposure to DU; for most terrestrial animals, likelihood for adverse reproduction effects ranges from 0.1% to 44%. However, for the lesser long-nosed bat, the effects are expected to occur (>99% likelihood) through the reduction in size and weight of offspring. Based on available DU data for the firing range at APG, DU uptake will not likely affect survival of aquatic plants and animals (<0.1% likelihood). Based on field and laboratory studies conducted at APG and YPG on pocket mice, kangaroo rat, white-throated woodrat, deer, and milfoil, body burden concentrations observed fall into the distributions simulated at both sites.     

The analysis and probabilistic health risk assessment of polycyclic aromatic hydrocarbons in cereal products

Environmental Science and Pollution Research - The analysis and probabilistic health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in cereal products were done by using magnetic...     

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.     

Fate and contaminant transport model-driven probabilistic human health risk assessment of DNAPL-contaminated site

In this study, fate and contaminant transport model-driven human health risk indexes were calculated due to the presence of dense non-aqueous phase liquids (DNAPLs) in the subsurface environment of air force base area in Florida, USA. Source concentration data of DNAPLs was used for the calculation of transport model-driven health risk indexes for the children and adult sub-population via direct oral ingestion and skin dermal contact exposure scenario using 10,000 Monte Carlo type simulations. The highest variation in the probability distribution of transformed DNAPL compound (cis-dichloroethene (cis-DCE) > vinyl chloride (VC)) was observed as compared to parent DNAPL (tetrachloroethene (PCE)) based on the 50-year simulation timespan. Transformed DNAPL compounds (VC, cis-DCE) posed the highest risk to human health for a longer duration (up to 15 years) in comparison to parent DNAPL (PCE), as non-carcinogenic hazard quotient varied from 400 to 1100. Carcinogenic health risks were observed as 3-order of magnitude higher than safe limit (HQ_Safe < 10⁻⁶) from 2nd to 5th year timespan and fall in the high-risk zone, indicating the need for a remediation plan for a contaminated site. Variance attribution analysis revealed that concentration, body weight, and exposure duration (contribution percentage – 70 to 95%) were the most important parameters, highlighting the impact of dispersivity and exposure model in the estimation of risk indexes. This approach can help decision-makers when a contaminated site with partial data on hydrogeological properties and with higher uncertainty in model parameters is to be assessed for the formulation of remediation measures.

     

Hazard assessment of chemicals in soil

Based on a stepwise (tiered) approach, degradation, adsorption and leaching tests as well as various effect tests (using plants, microorganisms and animals) are recommended for the testing of environmental chemicals. If, after the tests of tiers 1 and 2, the results of a monospecies-effect-test (including a safety factor) are within the range of the predicted exposure, the ecotoxicological hazard should be determined using a terrestrial model ecosystem. Some of the tests for the proposed strategy were selected from practical experience in testing environmental chemicals in the laboratory, and some on the basis of a comprehensive literature review.     

A Bayesian approach to probabilistic ecological risk assessment: risk comparison of nine toxic substances in Tokyo surface waters

Background, aim, and scope  

Quantitative risk comparison of toxic substances is necessary to decide which substances should be prioritized to achieve effective risk management. This study compared the ecological risk among nine major toxic substances (ammonia, bisphenol-A, chloroform, copper, hexavalent chromium, lead, manganese, nickel, and zinc) in Tokyo surface waters by adopting an integrated risk analysis procedure using Bayesian statistics.     

Risk assessment of environmental chemicals

This article is a summary from eleven important symposia. In these meetings, critical facts were discussed which are the necessary basis for the important legislation about toxic substances in Europe, in the U.S.A. and in Japan. This review article should also be of some help to the readers of “Chemosphere” for direct contacts with the experts mentioned. It is therefore an informative and coordinative survey, in which chemical and ecotoxicological details are largely omited.     

European risk assessment of LAS in agricultural soil revisited: species sensitivity distribution and risk estimates

Linear alkylbenzene sulphonate (LAS) is used at a rate of approximately 430,000 tons/y in Western Europe, mainly in laundry detergents. It is present in sewage sludge (70-5,600 mg/kg; 5-95th percentile) because of its high usage per capita, its sorption and precipitation in primary settlers, and its lack of degradation in anaerobic digesters. Immediately after amendment, calculated and measured concentrations are <1 to 60 mg LAS/kg soil. LAS biodegrades rapidly in soil with primary and ultimate half-lives of up to 7 and 30 days, respectively. Calculated residual concentrations after the averaging time (30 days) are 0.24-18 mg LAS/kg soil. The long-term ecotoxicity to soil microbiota is relatively low (EC10 >or=26 mg sludge-associated LAS/kg soil). An extensive review of the invertebrate and plant ecotoxicological data, combined with a probabilistic assessment approach, led to a PNEC value of 35 mg LAS/kg soil, i.e. the 5th percentile (HC5) of the species sensitivity distribution (lognormal distribution of the EC10 and NOEC values). Risk ratios were identified to fall within a range of 0.01 (median LAS concentration in sludge) to 0.1 (95th percentile) and always below 0.5 (maximum LAS concentration measured in sludge) according to various scenarios covering different factors such as local sewage influent concentration, water hardness, and sewage sludge stabilisation process. Based on the present information, it can be concluded that LAS does not represent an ecological risk in Western Europe when applied via normal sludge amendment to agricultural soil.     

Problems in testing and risk assessment of endocrine disrupting chemicals with regard to developmental toxicology.

Endocrine disrupting chemicals (EDCs) may affect mammalian development either indirectly (by impairing implantation, placental development, lactation, etc.) or directly, altering the maturation of target tissues. Current regulatory tests for reproductive/developmental toxicity should be carefully evaluated with regard to risk assessment of EDCs, considering hazard identification (are relevant endpoints being assessed?) and dose-response assessment (are sensitive NOEL/dose-response curves being provided?). Many in vitro and in vivo assays for sex steroid disruption are available; provided that the metabolic capacities of the assays are defined, they could be integrated in a sensitive battery for early detection of steroid-disrupting potentials. The screening battery should address further regulatory in vivo tests (e.g. what specific parameters have to be investigated). As regards dose-response, qualitative differences may be observed between lower and higher exposures, showing primary hormone-related effects and frank embryotoxicity, respectively. Other problems concern (a) the identification of critical developmental windows, according to hormone concentrations and/or receptor levels in the developing target tissues; (b) the potential for interactions between chemicals with common mechanism/target (e.g. xenoestrogens); (c) most important, besides sex steroids more attention should be given to other mechanisms of endocrine disruption, e.g., thyroid effects, which can be highly relevant to prenatal and postnatal development.     

Environmental risks of chemicals and genetically modified organisms: a comparison. Part II: Sustainability and precaution in risk assessment and risk management

The principles of precaution and sustainability require more consideration in the assessment of environmental risks posed by chemicals and genetically modified organisms. Instead of applying risk reduction measures when there are serious indications for damage, full scientific certainty is often waited for before taking action. The precautionary principle particularly should be applied in those cases in which the extent and probability of damage are uncertain, e.g. in the case of persistent chemicals which are additionally bioaccumulative or highly mobile. Based on these principles, environmental action targets for risks associated with GMOs and chemicals can be developed. Risk management not only includes statutory measures but also instruments designed to influence behaviour indirectly are important to achieve the goals. Particularly for risks of GMOs which provoke fear, risk communication is important. Some rules to which attention should be paid in communication with the public are presented.