Multi-route risk assessment from trihalomethanes in drinking water supplies

The USA is entering an era of energy diversity, and increasing nuclear capacity and concerns focus on accidents, security, waste, and pollution. Physical buffers that separate outsiders from nuclear facilities often support important natural ecosystems but may contain contaminants. The US Nuclear Regulatory Commission (NRC) licenses nuclear reactors; the applicant provides environmental assessments that serve as the basis for Environmental Impact Statements developed by NRC. We provide a template for the types of information needed for safe siting of nuclear facilities with buffers in three categories: ecological, fate and transport, and human health information that can be used for risk evaluations. Each item on the lists is an indicator for evaluation, and individual indicators can be selected for specific region. Ecological information needs include biodiversity (species, populations, communities) and structure and functioning of ecosystems, habitats, and landscapes, in addition to common, abundant, and unique species and endangered and rare ones. The key variables of fate and transport are sources of release for radionuclides and other chemicals, nature of releases (atmospheric vapors, subsurface liquids), features, and properties of environmental media (wind speed, direction and atmospheric stability, hydraulic gradient, hydraulic conductivity, groundwater chemistry). Human health aspects include receptor populations (demography, density, dispersion, and distance), potential pathways (drinking water sources, gardening, fishing), and exposure opportunities (lifestyle activities). For each of the three types of information needs, we expect that only a few of the indicators will be applicable to a particular site and that stakeholders should agree on a site-specific suite.     

Estimating overall persistence and long-range transport potential of persistent organic pollutants: a comparison of seven multimedia mass balance models and atmospheric transport models

Two different approaches to modeling the environmental fate of organic chemicals have been developed in recent years. The first approach is applied in multimedia box models, calculating average concentrations in homogeneous boxes which represent the different environmental media, based on intermedia partitioning, transport, and degradation processes. In the second approach, used in atmospheric transport models, the spatially and temporally variable atmospheric dynamics form the basis for calculating the environmental distribution of chemicals, from which also exchange processes to other environmental media are modeled. The main goal of the present study was to investigate if the multimedia mass balance models CliMoChem, SimpleBox, EVn-BETR, G-CIEMS, OECD Tool and the atmospheric transport models MSCE-POP and ADEPT predict the same rankings of the overall persistence (P(ov)) and long-range transport potential (LRTP) of POPs, and to explain differences and similarities between the rankings by the mass distributions and inter-compartment mass flows. The study was performed for a group of 14 reference chemicals. For P(ov), the models yield consistent results, owing to the large influence of phase partitioning parameters and degradation rate constants, which are used similarly by all models. Concerning LRTP, there are larger differences between the models than for P(ov), due to different LRTP calculation methods and spatial model resolutions. Between atmospheric transport models and multimedia fate models, no large differences in mass distributions and inter-compartment flows can be recognized. Deviations in mass flows are mainly caused by the geometrical design of the models.     

The devil is in the details (or the surface): impact of surface structure and surface energetics on understanding the behavior of nanomaterials in the environment

Metal and metal oxide nanomaterials are found in many consumer products for use in a wide range of applications including catalysis, sensors and contaminant remediation. Because of the extensive use of metal-based nanomaterials, there are concerns that these materials have the potential to get into the environment sometime during production, distribution, use and/or disposal. In particular, there exists the potential that they will make their way into water systems, e.g. drinking water systems, ground water systems, estuaries and lakes. In this review, some of the uncertainties in understanding nanoparticle behavior, which is often due to a lack of fundamental knowledge of the surface structure and surface energetics for very small particles, are discussed. Although classical models may provide guidance for understanding dissolution and aggregation of nanoparticles in water, it is the detailed surface structure and surface chemistry that are needed to accurately describe the surface free energy, a large component of the total free energy, in order to fully understand these processes. Without this information, it is difficult to develop a conceptual framework for understanding the fate, transport and potential toxicity of nanomaterials. Needed research areas to fill this void are discussed.     

Comparison of Nitrate Levels in Raw Water and Finished Water from Historical Monitoring Data on Iowa Municipal Drinking Water Supplies

Nitrate contamination of water sources is a concern where large amounts of nitrogen fertilizers are regularly applied to soils. Ingested nitrate from dietary sources and drinking water can be converted to nitrite and ultimately to N-nitroso compounds, many of which are known carcinogens. Epidemiologic studies of drinking water nitrate and cancer report mixed findings; a criticism is the use of nitrate concentrations from retrospective drinking water data to assign exposure levels. Residential point-of-use nitrate data are scarce; gaps in historical data for municipal supply finished water hamper exposure classification efforts. We used generalized linear regression models to estimate and compare historical raw water and finished water nitrate levels (1960s--1990s) in single source Iowa municipal supplies to determine whether raw water monitoring data could supplement finished water data to improve exposure assessment. Comparison of raw water and finished water samples (same sampling date) showed a significant difference in nitrate levels in municipalities using rivers; municipalities using other surface water or alluvial groundwater had no difference in nitrate levels. A regional aggregation of alluvial groundwater municipalities was constructed based on results from a previous study showing regional differences in nitrate contamination of private wells; results from this analysis were mixed, dependent upon region and decade. These analyses demonstrate using historical raw water nitrate monitoring data to supplement finished water data for exposure assessment is appropriate for individual Iowa municipal supplies using alluvial groundwater, lakes or reservoirs. Using alluvial raw water data on a regional basis is dependent on region and decade.     

Risk assessment near uncontrolled hazardous waste sites: Role of monitoring data

The traditional approach of coupling estimates of human exposures to individual chemicals with laboratory studies of the toxicity of the chemicals as the basis for quantitative assessments of risk is not adequate when considering problems near hazardous waste sites. For example, there are (a) too many chemicals and mixtures involved, (b) containment uncertainties, and (c) future exposure problems associated with groundwater and soil contamination. Among the items to be considered in expanding the dimensions of risk assessment methodologies of the past are (a) identification of chemical groups or of dominant toxic chemicals of principal concern and the likely man-made as well as natural pathways for environmental migration, (b) the role of biological monitoring in addition to traditional monitoring approaches, and (c) the coupling of monitoring data with past, current, and future population activity patterns and with epidemiological and other health data.Monitoring data is a key in risk assessments since there is little likelihood that materials balances or modelling will provide authoritative information concerning exposure levels. The use of monitoring data from control areas and from nationwide baseline surveys in developing comparative risk assessments is particularly important. Finally, recent experience provides us with a number of practical guidelines for designing and carrying out monitoring programs that will provide authoritative and useful data. *** DIRECT SUPPORT *** AZ802019 00002     

Fate and movement of atrazine, cyanazine, metolachlor and selected degradation products in water resources of the deep Loess Hills of Southwestern Iowa, USA

The environmental fate and movement of herbicides widely used for weed control in corn are assessed for a deep loess soil in southwestern Iowa. Beginning in the early 1980s, the herbicide-based weed control program emphasized the application of atrazine (ATR) or cyanazine (CYN) and metolachlor (MET) for both broadleaf and grass control. Between 1992 and 1995, concentrations of ATR, desethylatrazine (DEA), desisopropylatrazine (DIA), CYN and MET were measured in rainwater, both shallow and deep vadose zone water, and well water. Results show that the frequency of herbicide detections and the range and distribution of occurrences are dependent upon both landscape position and temporal inputs of recharge water from rainfall. Generally, DIA was observed more frequently and in higher mean concentration in well water than DEA, while DEA was observed more frequently than DIA in vadose zone groundwater. A chromatographic analogy is suggested to explain the occurrence patterns observed for both parent herbicide and degradation products within the unsaturated zone water. Analysis of rainwater samples collected during this time also revealed low concentrations of ATR, CYN and MET, with the timing of the detections indicative of non-local transport. Results show that the deep loess soil conducts both water and agricultural chemicals relatively rapidly and as such represents a production system which is vulnerable to contamination of shallow groundwater by herbicide-derived chemicals. Results also illustrate the importance of including major herbicide degradation products in water resource impact assessment studies.     

Global climate change and contaminants--an overview of opportunities and priorities for modelling the potential implications for long-term human exposure to organic compounds in the Arctic

This overview seeks to provide context and insight into the relative importance of different aspects related to global climate change for the exposure of Northern residents to organic contaminants. A key objective is to identify, from the perspective of researchers engaged in contaminant fate, transport and bioaccumulation modelling, the most useful research questions with respect to projecting the long-term trends in human exposure. Monitoring studies, modelling results, the magnitude of projected changes and simplified quantitative approaches are used to inform the discussion. Besides the influence of temperature on contaminant amplification and distribution, accumulation of organic contaminants in the Arctic is expected to be particularly sensitive to the reduction/elimination of sea-ice cover and also changes to the frequency and intensity of precipitation events (most notably for substances that are highly susceptible to precipitation scavenging). Changes to key food-web interactions, in particular the introduction of additional trophic levels, have the potential to exert a relatively high influence on contaminant exposure but the likelihood of such changes is difficult to assess. Similarly, changes in primary productivity and dynamics of organic matter in aquatic systems could be influential for very hydrophobic contaminants, but the magnitude of change that may occur is uncertain. Shifts in the amount and location of chemical use and emissions are key considerations, in particular if substances with relatively low long range transport potential are used in closer proximity to, or even within, the Arctic in the future. Temperature-dependent increases in emissions via (re)volatilization from primary and secondary sources outside the Arctic are also important in this regard. An increased frequency of boreal forest fires has relevance for compounds emitted via biomass burning and revolatilization from soil during/after burns but compound-specific analyses are limited by the availability of reliable emission factors. However, potentially more influential for human exposure than changes to the physical environment are changes in human behaviour. This includes the gradual displacement of traditional food items by imported foods from other regions, driven by prey availability and/or consumer preference, but also the possibility of increased exposure to chemicals used in packaging materials and other consumer products, driven by dietary and lifestyle choices.     

Polyfluoroalkyl compounds in the aquatic environment: a review of their occurrence and fate

The occurrence and fate of polyfluoroalkyl compounds (PFCs) in the aquatic environment has been recognized as one of the emerging issues in environmental chemistry. PFCs comprise a diverse group of chemicals that are widely used as processing additives during fluoropolymer production and as surfactants in consumer applications for over 50 years. PFCs are known to be persistent, bioaccumulative and have possible adverse effects on humans and wildlife. As a result, perfluorooctane sulfonate (PFOS) has been added to the persistent organic pollutants (POPs) list of the Stockholm Convention in May 2009. However, their homologues, neutral precursor compounds and new PFCs classes continue to be produced. In general, several PFCs from different classes have been detected ubiquitously in the aqueous environment while the concentrations usually range between pg and ng per litre for individual compounds. Sources of PFCs into the aqueous environment are both point sources (e.g., wastewater treatment plant effluents) and nonpoint sources (e.g., surface runoff). The detected congener composition in environmental samples depends on their physicochemical characteristics and may provide information to their sources and transport pathways. However, the dominant transport pathways of individual PFCs to remote regions have not been conclusively characterised to date. The objective of this article is to give an overview on existing knowledge of the occurrence, fate and processes of PFCs in the aquatic environment. Finally, this article identifies knowledge gaps, presents conclusions and recommendations for future work.     

Modelling the dispersion of treated wastewater in a shallow coastal wind-driven environment,Geographe Bay,Western Australia: implications for environmental management

Numerical models are useful for predicting the transport and fate of contaminants in dynamic marine environments, and are increasingly a practical solution to environmental impact assessments. In this study, a three-dimensional hydrodynamic model and field data were used to validate a far-field dispersion model that, in turn, was used to determine the fate of treated wastewater (TWW) discharged to the ocean via a submarine ocean outfall under hypothetical TWW flows. The models were validated with respect to bottom and surface water current speed and direction, and in situ measurements of total nitrogen and faecal coliforms. Variations in surface and bottom currents were accurately predicted by the model as were nutrient and coliform concentrations. Results indicated that the ocean circulation was predominately wind driven, evidenced by relatively small oscillations in the current speeds along the time-scale of the tide, and that dilution mixing zones were orientated in a predominantly north-eastern direction from the outfall and parallel to the coastline. Outputs of the model were used to determine the ‘footprint’ of the TWW plume under a differing discharge scenario and, particularly, whether the resultant changes in TWW contaminants, total nitrogen and faecal coliforms would meet local environmental quality objectives (EQO) for ecosystem integrity, shellfish harvesting and primary recreation. Modelling provided a practical solution for predicting the dilution of contaminants under a hypothetical discharge scenario and a means for determining the aerial extent of exclusion zones, where the EQOs for shellfish harvesting and primary recreation may not always be met. Results of this study add to the understanding of regional discharge conditions and provide a practical case study for managing impacts to marine environments under a differing TWW discharge scenario, in comparison to an existing scenario.     

Heterotrophic bacteria in drinking water distribution system: a review

The microbiological quality of drinking water in municipal water distribution systems (WDS) depends on several factors. Free residual chlorine and/or chloramines are typically used to minimize bacterial recontamination and/or regrowth in WDS. Despite such preventive measures, regrowth of heterotrophic (HPC) and opportunistic bacteria in bulk water and biofilms has yet to be controlled completely. No approach has shown complete success in eliminating biofilms or HPC bacteria from bulk water and pipe surfaces. Biofilms can provide shelter for pathogenic bacteria and protect these bacteria from disinfectants. Some HPC bacteria may be associated with aesthetic and non-life threatening diseases. Research to date has achieved important success in understanding occurrence and regrowth of bacteria in bulk water and biofilms in WDS. To achieve comprehensive understanding and to provide efficient control against bacteria regrowth, future research on bacteria regrowth dynamics and their implications is warranted. In this study, a review was performed on the literature published in this area. The findings and limitations of these papers are summarized. Occurrences of bacteria in WDS, factors affecting bacteria regrowth in bulk water and biofilms, bacteria control strategies, sources of nutrients, human health risks from bacterial exposure, modelling of bacteria regrowth and methods of bacteria sampling and detection and quantification are investigated. Advances to date are noted, and future research needs are identified. Finally, research directions are proposed to effectively control HPC and opportunistic bacteria in bulk water and biofilms in WDS.     

Multi-level modelling of chlorination by-product presence in drinking water distribution systems for human exposure assessment purposes

During drinking water treatment and distribution, chlorine reacts with organic matter occurring in water to form various chlorination by-products (CBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). This paper presents the occurrence of THMs and HAAs in different water distribution systems (DS) of the same region and their modelling for exposure assessment purposes. This study was conducted in eight DS supplying chlorinated water to the population of Québec City, Canada. These systems differ in type of water source (i.e. surface, ground or mixed water), in treatment applied at the plant, and in size and structure of the DS. Two spatio-temporal databases for THMs and HAAs were implemented, one for model development and the other for model validation. The analysis of the data demonstrates significant seasonal and spatial variations of these compounds. A multi-level statistical modelling approach was applied to estimate the ranges for occurrence of THMs and HAAs in the eight DS (i.e. a single model for the study region for each CBP species). The modelling approach integrates available or easily measurable parameters. For both THMs and HAAs, a two-level model considering a sampling-site random effect was selected among various models initially developed. The model capacity for estimating the presence of THMs and HAAs in drinking water and its usefulness for exposure assessment purposes in the studied region was demonstrated.     

Comparative cancer risk assessment of THMs in drinking water from well water sources and surface water sources

This research evaluates the lifetime cancer risks from trihalomethanes in Tehran's drinking water. The Trihalomethanes were measured in seven different water districts. Sixty-three samples were taken from tap water across the city for 7 months. The samples were analyzed for trihalomethanes using US EPA method 524.2. The average concentration of total trihalomethanes in different districts were between 0.81 and 9.0 μg/L, and the highest concentrations were detected in district 2 at 19.5 μg/L. Total lifetime cancer risks assessment from exposure to trihalomethanes in drinking water (ingestion, inhalation, and skin routes) were performed for people living in different districts in Tehran. The lifetime cancer risk was 7.19 × 10(-5) in district 2 (a more affluent neighborhood) where mostly surface water sources is used to supply drinking water and 9.38 × 10(-6) in district 7 (a less affluent neighborhood) which is mainly supplied with well water sources. Based on the population data, the total expected lifetime cancer cases from exposure to trihalomethanes are 104, 108, 81, 81, 41, 27, and three for districts 1 through 7, respectively. The average lifetime cancer risk was 4.33 × 10(-5) which means a total of 606 lifetime cancer cases for the entire province of Tehran. The highest risk from THMs seems to be from the inhalation route followed by ingestion and dermal contacts.     

Visualising the equilibrium distribution and mobility of organic contaminants in soil using the chemical partitioning space

Assessing the behaviour of organic chemicals in soil is a complex task as it is governed by the physical chemical properties of the chemicals, the characteristics of the soil as well as the ambient conditions of the environment. The chemical partitioning space, defined by the air-water partition coefficient (K(AW)) and the soil organic carbon-water partition coefficient (K(OC)), was employed to visualize the equilibrium distribution of organic contaminants between the air-filled pores, the pore water and the solid phases of the bulk soil and the relative importance of the three transport processes removing contaminants from soil (evaporation, leaching and particle erosion). The partitioning properties of twenty neutral organic chemicals (i.e. herbicides, pharmaceuticals, polychlorinated biphenyls and volatile chemicals) were estimated using poly-parameter linear free energy relationships and superimposed onto these maps. This allows instantaneous estimation of the equilibrium phase distribution and mobility of neutral organic chemicals in soil. Although there is a link between the major phase and the dominant transport process, such that chemicals found in air-filled pore space are subject to evaporation, those in water-filled pore space undergo leaching and those in the sorbed phase are associated with particle erosion, the partitioning coefficient thresholds for distribution and mobility can often deviate by many orders of magnitude. In particular, even a small fraction of chemical in pore water or pore air allows for evaporation and leaching to dominate over solid phase transport. Multiple maps that represent soils that differ in the amount and type of soil organic matter, water saturation, temperature, depth of surface soil horizon, and mineral matters were evaluated.     

RISK ASSESSMENT METHODOLOGY FOR KARST AQUIFERS: (2) SOLUTE-TRANSPORT MODELING

Ground-water flow and solute-transport simulation modeling are major components of most exposure and risk assessments of contaminated aquifers. Model simulations provide information on the spatial and temporal distributions of contaminants in subsurface media but are difficult to apply to karst aquifers in which conduit flow is important. Ground-water flow and solute transport in karst conduits typically display rapid-flow velocities, turbulent-flow regimes, concentrated pollutant-mass discharge, and exhibit open-channel or closed-conduit flow. Conventional ground-water models, dependent on the applicability of Darcy`s law, are inappropriate when applied to karst aquifers because of the (1) nonapplicability of Darcian-flow parameters, (2) typically nonlaminar flow regime, and (3) inability to locate the karst conduits through which most flow and contaminant transport occurs. Surface-water flow and solute-transport models conditioned on a set of parameters determined empirically from quantitative ground-water tracing studies may be effectively used to render fate-and-transport values of contaminants in karst conduits. Hydraulic-flow and geometric parameters developed in a companion paper were used in the surface-water model, TOXI5, to simulate hypothetical slug and continuous-source releases of ethylbenzene in a karst conduit. TOXI5 simulation results showed considerable improvement for predicted ethylbenzene-transport rates and concentrations over qualitative tracing and analytical ground-water model results. Ethylbenzene concentrations predicted by TOXI5 simulations were evaluated in exposure and risk assessment models.     

Empirical evaluation of spatial and non-spatial European-scale multimedia fate models: results and implications for chemical risk assessment

Multimedia environmental fate models are commonly-applied tools for assessing the fate and distribution of contaminants in the environment. Owing to the large number of chemicals in use and the paucity of monitoring data, such models are often adopted as part of decision-support systems for chemical risk assessment. The purpose of this study was to evaluate the performance of three multimedia environmental fate models (spatially- and non-spatially-explicit) at a European scale. The assessment was conducted for four polycyclic aromatic hydrocarbons (PAHs) and hexachlorobenzene (HCB) and compared predicted and median observed concentrations using monitoring data collected for air, water, sediments and soils. Model performance in the air compartment was reasonable for all models included in the evaluation exercise as predicted concentrations were typically within a factor of 3 of the median observed concentrations. Furthermore, there was good correspondence between predictions and observations in regions that had elevated median observed concentrations for both spatially-explicit models. On the other hand, all three models consistently underestimated median observed concentrations in sediment and soil by 1-3 orders of magnitude. Although regions with elevated median observed concentrations in these environmental media were broadly identified by the spatially-explicit models, the magnitude of the discrepancy between predicted and median observed concentrations is of concern in the context of chemical risk assessment. These results were discussed in terms of factors influencing model performance such as the steady-state assumption, inaccuracies in emission estimates and the representativeness of monitoring data.     

Concentrations of asbestos fibers and metals in drinking water caused by natural crocidolite asbestos in the soil from a rural area

Asbestos fibers and metals in drinking water are of significant importance to the field of asbestos toxicology. However, little is known about asbestos fibers and metals in drinking water caused by naturally occurring asbestos. Therefore, concentrations of asbestos fibers and metals in well and surface waters from asbestos and control areas were measured by scanning electron microscopy (SEM), inductively coupled plasma (ICP) optical emission spectrometer, and ICP–mass spectrometry in this study. The results indicated that the mean concentration of asbestos fibers was 42.34 millions of fibers per liter by SEM, which was much higher than the permission exposure level. The main compositions of both asbestos fibers in crocidolite mineral and in drinking water were Na, Mg, Fe, and Si based on energy dispersive X-ray analysis. This revealed that the drinking water has been contaminated by asbestos fibers from crocidolite mineral in soil and rock. Except for Cr, Pb, Zn, and Mn, the mean concentrations of Ni, Na, Mg, K, Fe, Ca, and SiO₂ were much higher in both surface water and well waters from the asbestos area than in well water from the control area. The results of principal component and cluster analyses indicated that the metals in surface and well waters from the asbestos area were significantly influenced by crocidolite mineral in soil and rock. In the asbestos area, the mean concentrations of asbestos fibers and Ni, Na, Mg, K, Fe, Ca, and SiO₂ were higher in surface and well waters, indicating that asbestos fibers and the metals were significantly influenced by crocidolite in soil and rock.     

Presence of steroid hormones and antibiotics in surface water of agricultural, suburban and mixed-use areas

The occurrence of pharmaceutically active chemicals (PACs) in the natural aquatic environment is recognized as an emerging issue due to the potential adverse effects these compounds pose to aquatic life and humans. This study presents the monitoring of two major categories of PACs in surface water: steroid hormones and antibiotics. Surface water samples were collected in the fall season from 21 locations in suburban (4), agricultural (5) and mixed (12) use suburban and agricultural areas. The water samples collected were analyzed using GC/MS for aqueous concentration of eleven steroid hormones: six natural (17alpha-estradiol, 17beta-estradiol, estrone, estriol, 17alpha-dihydroequilin, progesterone) and five synthetic (gestodene, norgestrel, levonorgestrel, medrogestone, trimegestone). In addition, 12 antibiotics (oxytetracycline, chlorotetracycline, tetracycline, sulfamethoxazole, sulfamethazine, trimethoprim, lincomycin, norfloxacin, ofloxacin, roxithromycin, erythromycin, tylosin tartrate) were analyzed using LC/MS. Steroid hormones detected in surface water were: 17alpha-estradiol, 17beta-estradiol, 17alpha-dihydroequilin, estriol, estrone, progesterone and trimegestone. Estrone had the highest detection frequency of >90% with concentrations ranging from 0.6 to 2.6 ng/l. The second most frequently detected estrogen was estriol (>80%) with concentrations ranging from 0.8 to 19 ng/l. The detection frequency varied at different sampling locations. No antibiotics were detected in the 21 streams sampled. This study aims to give a better understanding on the presence, fate and transport of PACs derived from humans and animals.     

Ecotoxicological Classification of the Berlin River System Using Bioassays in Respect to the European Water Framework Directive

Bioassays as well as biochemical responses (biomarkers) in ecosystems due to environmental stress provide us with signals (environmentally signalling) of potential damage in the environment. If these responses are perceived in this early stage in ecosystems, the eventual damage can be prevented. Once ecosystem damage has occurred, the remedial action processes for recovery could be expensive and pose certain logistical problems. Ideally, “early warning signals” in ecosystems using sensing systems of biochemical responses (biomarkers) would not only tell us the initial levels of damage, but these signals will also provide us with answers by the development of control strategies and precautionary measures in respect to the European Water Framework Directive (WFD). Clear technical guidelines or technical specifications on monitoring are necessary to establish and characterise reference conditions for use in an ecological status classification system for surface water bodies. For the Ecotoxicological Risk Assessment (ERA) of endocrine effects we used an approach of the exposure – dose – response concept. Based on the “Ecototoxicological Classification System of Sediments” that uses pT-values to classify effects in different river systems, we transferred the bio-monitoring data to the five-level ecological system of the WFD. To understand the complexity of the structure of populations and processes behind the health of populations, communities and ecosystems an ERA should establish links between natural factors, chemicals, and biological responses so as to assess causality. So, our ecological monitoring assessment has incorporated exposure & effects data.