Integrated exposure-monitoring

This paper outlines briefly the history of radiation protection, touches on some of the early incidents of overexposure, describes monitoring (detection and measurement) methods and the development of standards for health protection, and compares the monitoring of radioactive materials to that of nonradioactive toxic chemicals. The authors suggest that the lessons learned from the radiation experience will be helpful in dealing with the current problems of hazardous chemicals. *** DIRECT SUPPORT *** AZ802019 00005     

Trends in ambient concentrations of agrochemicals in humans and the environment of the United States

Uses of pesticides and related agrochemicals have been regulated in the United States since 1948. The United States government has supported human and environmental monitoring for pesticides and selected toxic chemicals for the past 15 yr. The initial ambient monitoring systems were designed to determine average concentrations of pesticides and related chemicals in human and environmental media on a nationwide basis and determine changes in these concentrations over time. The results of these surveys showed that almost all of the general human population and various environmental components contained low concentrations of chlorinated pesticides. As the Environmental Protection Agency (EPA) restricted many uses of the chlorinated pesticides, the organophosphorous and carbamate pesticides which replaced them were not as easily monitored by ambient surveys. Special monitoring studies had to be done more frequently to produce data on these compounds which were not as persistent or accumulative in the environment. Currently, a re-evalution has begun to determine pesticide monitoring data needs for the next 5 to 10 yr, modify existing ambient surveys, and plan needed short-term studies to efficiently meet regulatory data needs. Ambient monitoring for trends in chemical levels in humans and the environment will continue in the United States at a reduced level, and many exposure data needs will be met with use-specific monitoring studies.Presented at the International Conference on Environmental Hazards of Agrochemicals in Developing Countries, 8–12 November, 1983 in Alexandria, Egypt.     

Assessing workplace chemical exposures: the role of exposure monitoring

Occupational exposure is the condition of being subjected through employment to a chemical, physical, or biological agent, or to a specific process, practice, behavior, or organization of work. Exposure to a chemical agent is typically the contact of that agent with the outer boundary of a subject, such as the respiratory system, skin, or digestive system. In occupational hygiene we are most concerned with exposure through the respiratory system, although, increasingly we are concerned with the results of dermal exposures, including those exposures to the skin that can be transferred to the mouth and digestive system. This presentation will detail methods available for assessing personal exposures to chemicals through monitoring. The results from monitoring can then be compared to established guidelines and regulations, although this is not the only rationale for making measurements. These monitoring methods are currently used around the world to establish the benchmark hazard from which risk to the worker can be predicted. The presentation will describe the general techniques for assessing exposures to the respiratory system from chemical gases and vapors, chemical dusts, and exposures to the skin from bulk chemicals or chemical contamination of surfaces. For respiratory exposures, direct-reading instruments are available for spot measurements, and for monitoring short-term fluctuations in concentration. However, most standards and regulations are based on time-integrated (time-weighted average) exposures, requiring longer-term integrative methods. Therefore, the specific focus of this review will be the methods available for full work-shift sampling. For gases and vapors this will include taking whole-air samples in canisters or polymer bags, or concentration of chemicals by absorption in liquids or adsorption on solid sorbents, with subsequent chemical analysis. Chemical concentration can take place by pumping air through the sorbing media, or by allowing molecules to diffuse to the sorbent surface. Transfer of the collected chemicals to the analytical instrumentation can be accomplished using solvent displacement and injection, or through the application of heat to bring the collected molecules back into the vapor phase. For particles, the particle size is important as this determines the site of deposition in the lungs, and so time-integrated sampling on filters using various types of size-selective samplers is preferred. Finally, some techniques that have been used to assess the potential for chemical contamination of the skin are presented. Biomonitoring is another tool that can be used to assess exposure, and the results are more relevant to dosimetric considerations than exposure. Biomonitoring is a complex subject worthy of a separate review, and will be considered only briefly here.     

The design of long-term air quality monitoring networks in urban areas using a spatiotemporal approach

The implementation and maintenance of an air pollution monitoring program can be expensive and time consuming, especially when the aim is for long-term monitoring over a significant area. Consequently, it is essential that sites are optimized to provide the best representative cover while minimizing costs. In the past, there has been a tendency to locate sampling stations at pollution hot-spots. While this is acceptable for determining a maximum potential exposure or identifying the extent of a risk, there are limitations to this approach when assessing the potential impact of any future abatement strategies or determining the level of exposure outside the vicinity. This paper presents an approach in which representative air quality assessments can be undertaken for an urban area using the minimum number of measurement sites. A novel methodology is described that involves site selection to capture the maximum variance in measured pollutants, while minimizing spatiotemporal autocorrelation between the selected sites. A case study is presented for Yazd, Iran. Overall, the results show that the proposed methodology can be effective and enable the long-term monitoring of air pollution to be undertaken on a cost-effective basis in urban areas. In addition, there is the potential for the methodology to be utilized for other forms of pollution (e.g., water, soil, and noise).     

A Critical Analysis of Illinois’ Fish Mercury Monitoring Program, 1974–1998

Mercury contamination in fish is a serious public health concern that contrasts with other health benefits of eating fish. Like most US states, Illinois has monitored fish mercury contamination for decades to warn the public of mercury exposure risks by consuming fish. Has this monitoring program been effective in detecting public mercury exposure risks? I analyzed fish mercury contamination data from Illinois inland lakes (1974–1998; >?2,300 samples, 18 fish species, 149 lakes) and found that: (a) sampling and analyses have been severely limited since 1985; (b) sampling effort varied widely among lakes and species, and (c) trends and spatial patterns were confused by this variability. As a result of a severely limited and nonstrategic monitoring program, public mercury exposure risks via Illinois fish consumption remain unclear, despite much effort over many years. Illinois monitors fewer fish per angler than many US states, but is not alone in this regard. Illinois should resurrect and redesign its fish contaminant monitoring program to one that strategically and systematically assesses human mercury exposure risk. Other US states and nations may also benefit from similar retrospective examinations of monitoring programs intended to protect public health.     

Integrated exposure monitoring for health risk assessment

Risk estimation and risk evaluation in society are often done separately for pollutants in ambient air, water, food and industrial air. The need for evaluating total exposure is pointed out. Ongoing international programs are referred to. Biological monitoring in combination with environmental monitoring constitutes a promising step towards an integrated exposure monitoring for health risk assessment. The rationale for such an approach is discussed. The need of monitoring not only single substances but a combination of substances is exemplified. A strengthening of the basic research in related fields will widely increase future possibilities for health-related surveillance.     

Assessment of risk to public health posed by persistent organochlorine pesticide residues in milk and milk products in Mumbai, India

The risk posed by the presence of organochlorine pesticides in milk and milk products was estimated for the population of Mumbai. To determine the levels of organochlorine pesticides in milk and milk products, a monitoring study was carried out in and around Mumbai City. 520 samples of milk and milk products of different brands were considered in this study. A survey was also conducted to determine the mean daily consumption of milk and milk products by different age groups and this data was used to evaluate the daily exposure to the public. Non-cancer effects were evaluated by comparing the predicted exposure distributions to the published guidance values. For chemicals identified as potential human carcinogens, cancer risk was evaluated using standard methodology. The majority of the chlorinated pesticides identified in the milk and milk product samples studied were found to be at levels which do not pose unacceptable risks to the public, with the exception of alpha-HCH. The cancer risk estimated for this chemical slightly exceeds the US EPA guidance value.     

Biological monitoring versus air monitoring strategies in assessing environmental-occupational exposure

Assessment of environmental and occupational exposure to chemicals can be performed with environmental monitoring (EM) and biological monitoring (BM). Biological monitoring was for a long time considered as a method complementary to environmental monitoring. At present this attitude is changing and in certain areas biological monitoring is applied as the method of choice for exposure and health-risk assessment. This paper examines advantages and disadvantages of those two approaches. In occupational settings environmental monitoring of exposure to VOCs seems to be superior to biological monitoring (possibility of simultaneous determination of components of mixtures, simple interpretation, possibility of evaluation of short-term exposure to local irritants). In the case of this group of compounds BM can be useful in selected cases such as evaluation of dermal absorption or efficiency of protective measures. In the case of metals both forms of monitoring can be used depending on the available methods for interpretation of results. BM of exposure may be considered as superior for evaluating the effects of exposure to lead, cadmium and mercury. However, quantitative evaluation of cancer risk after exposure to arsenic or chromium is possible only on the basis of determination in the air and the use of unit risk values. Both environmental and biological monitoring are useful for evaluation of occupational and environmental exposure to polycyclic aromatic hydrocarbons (PAHs). In certain areas such as evaluation of exposure to external tobacco smoking, cytostatic drugs, and pesticides, biological monitoring is the method of choice used for individual exposure assessment or tracing the trends of environmental exposure.     

Integrated monitoring and assessment of soil restoration treatments in the Lake Tahoe Basin

Revegetation and soil restoration efforts, often associated with erosion control measures on disturbed soils, are rarely monitored or otherwise evaluated in terms of improved hydrologic, much less, ecologic function and longer term sustainability. As in many watersheds, sediment is a key parameter of concern in the Tahoe Basin, particularly fine sediments less than about ten microns. Numerous erosion control measures deployed in the Basin during the past several decades have under-performed, or simply failed after a few years and new soil restoration methods of erosion control are under investigation. We outline a comprehensive, integrated field-based evaluation and assessment of the hydrologic function associated with these soil restoration methods with the hypothesis that restoration of sustainable function will result in longer term erosion control benefits than that currently achieved with more commonly used surface treatment methods (e.g. straw/mulch covers and hydroseeding). The monitoring includes cover-point and ocular assessments of plant cover, species type and diversity; soil sampling for nutrient status; rainfall simulation measurement of infiltration and runoff rates; cone penetrometer measurements of soil compaction and thickness of mulch layer depths. Through multi-year hydrologic and vegetation monitoring at ten sites and 120 plots, we illustrate the results obtained from the integrated monitoring program and describe how it might guide future restoration efforts and monitoring assessments.     

The environmental specimen banking project of the Federal Republic of Germany

Thousands of chemicals are on the market, but only in a few exceptional cases is it known where these chemicals remain in the environment and what effects they are able toexert in correlation to their environmental concentration. In addition to monitoring the actual concentrations of chemicals in the environment, it is necessary to establish an environmental specimen banking program which will, in the future, make possible the retrospective monitoring of chemicals. The feasibility of such a program is being studied in a joint U.S.-German pilot project. The German project is described here, including its organizational structure, technical and scientific considerations, and methods of specimen selection.     

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.     

Toward a Practical Method for Setting Screening-Level, Ecological Risk-Based Water Temperature Criteria and Monitoring Compliance

We integrated basic concepts from fisheries science and toxicological risk assessment to form a potential method for setting screening-level, risk-based, site-specific water quality objectives for temperature. In summary, the proposed approach: (a) uses temperature impacts upon specific growth as a measure of chronic (cumulative) temperature effects; (b) explicitly incorporates the consequences of both magnitude and cumulative duration of exposures; (c) adjusts the result for local watershed conditions, reducing the likelihood that naturally warm systems are identified as thermally polluted while helping to ensure that naturally cool systems are closely monitored for ecologically harmful changes in thermal regime; and (d) expresses the net result both graphically and as a risk quotient, RQ, closely analogous to that used in toxicological risk assessments. The latter yields a site-specific, risk-based water quality objective and may serve as a straightforward decision rule for environmental managers. The method was applied to historical data from a small British Columbia stream subject to increasing urban development pressures. We also illustrate how the technique might be used to explore potential climatic change impacts, using coupled general circulation model predictions in conjunction with empirical downscaling. Overall, the method and results are presented as an introduction and illustration of concept, intended as a step toward the development of a logistically feasible risk-based approach to establishing screening-level, site-specific water temperature objectives, and monitoring compliance, in the context of large-scale, many-site, environmental monitoring networks. With further work, the technique offers potential to fill the gap between the temperature threshold-based targets typically specified in regulatory guidelines, which may be hydroecologically unrealistic, and detailed biophysical modelling, which typically is logistically infeasible in a day-to-day environmental monitoring and management context.     

Environmental impact from agrochemicals in Bali (Indonesia)

Irrigation of paddy has been practised for centuries in Bali, based on the use of upland weirs for diverting river waters to irrigate downstreams lands ranging from upland terraces to flat coastal plains. While in earlier times, traditional irrigation practices have met the island's food needs, in recent decades an increasing population has increased food requirements to levels surpassing the productivity of traditional methods. Government assistance programs were initiated beginning in about 1960, and a major new program, called the Bali Irrigation Project, is now being implemented. These programs recognize that little additional farm lands will be available, hence their objective is to increase productivity through intensified agriculture, including the use of high-yield rice varieties and increasing amounts of agricultural chemicals, including both fertilizers and pesticides. The feasibility study for the Bali Irrigation Project included an evaluation of the pollutional effects of agricultural chemicals used in Bali. The study showed that past use of hard organochlorides has pervasively polluted the island's soil and water resources and, while the Government's programs now use only relatively degradable chemicals, considerable environmental damage has already occurred and much care will be needed in avoiding the use of hard toxics in the future. The study also indicated no adverse effects from increased use of fertilizers.     

Assessing urban runoff program progress through a dry weather hybrid reconnaissance monitoring design

Characterizing dry weather conditions in urban Municipal Separate Storm Sewer Systems (MS4s), and then prioritizing and addressing problems due to urban pollutants, is a daunting challenge. The size and complexity of most MS4s and the ephemeral nature of many dry weather problems hamper efforts to identify and eliminate pollutant sources, and to track trends in condition. As a result, assessing overall program progress has proven difficult. We describe a hybrid dry weather urban monitoring design from southern California that combines probabilistic and targeted sampling to rigorously identify and prioritize problems and track program progress. Data from probabilistic sites define the urban background and establish tolerance intervals, which identify sites that persistently exceed the overall urban background. Targeted sites focus on locations where nearby activities and/or past history suggest that pollutant levels will be elevated. Embedding targeted monitoring within a probabilistic design enables data from targeted sites to be interpreted in a more meaningful regional context. Data from all sites are also used to construct site- and pollutant-specific control charts. These charts quickly identify instances where a site's behavior significantly changes, compared to its past behavior, suggesting an active source in the upstream drainage area. The hybrid design, and the use of formal statistical tools (tolerance intervals and control charts), permit the program to systematically prioritize problematic sites, compare conditions to the regional urban background, and track trends over time. In addition, the program's design allows several measures of program progress to be defined and thus consistently followed over time. Such hybrid designs can provide substantial advantages compared to more traditional monitoring approaches.     

PFOS or PreFOS? Are perfluorooctane sulfonate precursors (PreFOS) important determinants of human and environmental perfluorooctane sulfonate (PFOS) exposure?

The extent to which perfluorooctanesulfonate precursors (PreFOS) play a role in human or environmental exposure to perfluorooctanesulfonate (PFOS) is not well characterized. The diversity of manufactured PreFOS and its degradation products (e.g. C(8)F(17)SO(2)R and C(8)F(17)SO(2)NR'R', where R is H or F, and R' and R' are various) has made it difficult to track their fate. Temporal trends of PFOS in both humans and wildlife are discrepant, thus it is difficult to predict future exposure, and hypotheses about the role of PreFOS have been raised. Although abiotic degradation of commercially important PreFOS materials requires further research, current data suggest that the yield of PFOS is negligible or minor. On the other hand, in vivo biotransformation of PreFOS yields PFOS as the major metabolite, and >32% yields have been observed. In Canadians, exposure to PreFOS was equivalent or greater than direct PFOS exposure prior to 2002. In most ocean water, PFOS is dominant to PreFOS, but in the oceans east of Greenland there may be more PreFOS than PFOS, consistent with the fact that whales and humans in this region also show evidence of substantial PreFOS exposure. Quantitative assessments of PFOS body-burdens coming from PreFOS are complicated by the fact that PreFOS partitions to the cellular fraction of blood, thus biomonitoring in serum under predicts PreFOS relative to PFOS. Many unknowns exist that prevent accurate modelling, thus analytical methods that can distinguish directly manufactured PFOS, from PFOS that has been biotransformed from PreFOS, should be applied in future human and environmental monitoring. Two new source tracking principles are presented and applied to human serum.     

Application of multimedia exposure assessment to drinking water

A potentially important exposure route for humans is the ingestion of chemicals via drinking water. If comprehensive exposure assessments are to be completed for either existing or proposed new chemicals and cost effective control strategies developed, then a quantitative understanding of multimedia transport and fate of specific chemical pollutants must be achieved. Mathematical models provide a powerful framework into which quantitative relationships may be placed to provide guidance in reaching water quality goals. Existing, state-of-the-art media-specific toxic organic transport and fate models for atmospheric (DiDOT), land surface (NPS) and surface water processes (EXAMS) and potable water treatment (WTP) have been linked to demonstrate the technical feasibility of such an approach. Limited application and sensitivity testing of this linked modeling system has shown that the impact of various source loadings and control strategies on drinking water quality can be estimated.     

Human Risk Assessment for Heavy Metals and as Contamination in the Abandoned Metal Mine Areas, Korea

Cleanup goals for the contaminated sites are established on the basis of risk assessments and rely on the estimated toxicity of the chemicals of concern (COC). Toxicity estimates are based on bioavailability causing risk of adverse health effects on humans. In this study, bioavailability of As, Cu, Pb and Zn in soil was determined by SBET (Simple Bioavailability Extraction Test), and chemical analysis for groundwater and stream water collected from the abandoned mine areas (Dukeum, Dongil, Dongjung, Myungbong and Songchun mine areas) was conducted. High values of cancer risk for As (1.16×10⁻⁵) were detected through soil ingestion pathways in the Songchun mine area and assessed through water exposure pathways in the all mines except Dukeum. The hazard index value for As in the Songchun mine area (3.625) exceeded 1.0. The results indicated that the ingestion of As-contaminated soil and water by local inhabitants can pose a potential health threat in these mine areas.     

找准定位 科学布局 抓住关键 确保环境监测改革取得扎实成效

环境监测是生态文明建设和环境保护的重要基础。目前,环境监测改革已经进入关键阶段。研究在梳理环境监测基本定位的基础上,分析了各项改革的系统性、协同性,提出要理顺各级监测事权与支出责任,化解地方干预,优化环境监测发展的总体布局,加强环境质量监测和执法监测,建设独立、公正、权威、高效的生态环境监测体系,确保改革取得扎实成效。     

Indicators of ecosystem health at the species level and the example of selenium effects on fish

Chemical monitoring of aquatic ecosystems describes the chemical exposures of aquatic biota and measures the success of pollution control. However, meeting water quality criteria cannot assure that aquatic biota are protected from the effects of unexpected chemicals, mixtures and interactions between toxicity and environmental stressors.Biological monitoring is an obvious solution since aquatic biota integrate spatial and temporal variations in exposure to many simultaneous stressors. Top predators, typical of specific ecosystems (e.g. lake trout in cold water oligotrophic lakes) indicate whether environmental criteria have been met. The presence of naturally reproducing, self-sustaining and productive stocks of edible fish demonstrates a high quality environment. If these conditions are not met, there is a clear sign of environmental degradation. Specific changes in population structure and performance may also diagnose which life stage is affected and the nature of the stressor.Unfortunately, environmental managers cannot rely solely on populations, communities or ecosystems to indicate chmical effects. The lag between identifying a problem and finding a cause may destroy the resource that we wish to protect, particularly where chemicals are persistent.A solution to this dilemma is the measurement of primary or secondary responses of individual organisms to chemical exposure. Since toxicity at any level of organization must start with a reaction between a chemical and a biological substrate, these responses are the most sensitive and earliest sign of chemical exposure and effect.Application of this idea requires research on molecular mechanisms of chemical toxicity in aquatic biota and adaptation of existing mammalian diagnostic tools. Since relevance of biochemical responses to populations and ecosystems is not obvious, there is a need to study the links between chemical exposure and responses of individuals, populations and ecosystems.The recognition of chemical problems and cause-effect relationships requires the integration of chemical and biological monitoring, using the principles of epidemiology to test the strength of relationships and to identify specific research needs. The contamination of a reservoir with selenium and impacts on fish populations provide an excellent example of this approach.