Bioavailability: Exposure, Dose and Risk Assessment

“AMORE” Decision Support System for probabilistic Ecological Risk Assessment - Part I: Exposure and risk assessment of the case study on cyanide

Risk assessments have assumed an increasingly important role in the management of risks in this country. The determination of which pollutants or public health issues are to be regulated, the degree and extent of regulation, and the priority assigned to particular problems are all areas of risk assessment that influence the country's $100 billion annual investment in environmental protection. Recent trends in public policy have brought the practice of risk assessment under greater scrutiny. As policy makers increasingly insist that specific numerical risk levels (so-called bright lines) be incorporated into regulatory decisions, the stakes for good risk assessment practice, already high, are raised even further. Enhancing the scientific basis of risk assessments was a major goal of the Workshop on Exposure Databases. In this article, we present the Risk Assessment Work Group's evaluation of the use of exposurerelated databases in risk assessment and the group's recommendations for improvement. The work group's discussion focused on the availability, suitability, and quality of data that underly exposure assessments, a critical component of risk assessment. The work group established a framework for evaluation, based on exposure scenarios typically used in regulatory decisions. The scenarios included examples from Superfund, the Clean Air Act, the Toxic Substances Control Act, and other regulatory programs. These scenarios were used to illustrate current use of exposure data, to highlight gaps in existing data sources, and to discuss how improved exposure information can improve risk assessments. The work group concluded that many of the databases available are designed for purposes that do not meet exposure and risk assessment needs. Substantial gaps exist in measurements of actual human exposure and in the data necessary to model exposures, to characterize distributions of exposure, to identify high-risk groups, and to identify possible environmental inequities in exposure. The work group, on the basis of its findings, made both short-term and longer-term recommendations for improving the collection of exposure data in the future.

Objectives: Exposure Assessment for workplace hazards where the exposure level is below occupational exposure limits(OELs) has been performed without considering either the degrees of risk or exposure levels and has failed to lead to intervention in many cases. The objective of this study was to suggest and test an application framework for risk assessment methodology under the current exposure assessment system in Korea. Materials: First, we investigated the exposure assessment systems in Korea and other countries. To adopt some risk assessment techniques, we also analyzed risk assessment systems and compared them to exposure assessment systems. A few suggestions were made. We held a public hearing during an industrial hygiene conference and took surveys using a questionnaire. Results: The first suggestion was to implement the risk assessment and exposure assessment through a "one-stop" system. In that case, one expected question would be who has been doing the jobs so far. In most cases, industrial hygiene consulting services or laboratories have been performing exposure assessment for business owners. Business owners are required to perform risk assessment. As two different groups of people will be required to implement two things in a one-stop system, they need to share information. As an information vehicle to share information, commonly filed survey checklists were suggested. The second suggestion was to categorize exposure level into four groups instead of the current binary divisions based on OELs. In the risk assessment system, exposure level is divided into four groups utilizing the cut-points of 10%, 50%, and 100% of OELs. The same schema can be adopted in the exposure assessment system and different levels of requirements can be assigned for each group. The third suggestion was regarding the regulation system. To provide the suggestions some thrust toward being implemented in the field, changes should be made in the legal system. Two different types of new exposure assessment result reporting forms were suggested. Some investigations such as an ergonomic survey are officially accepted as risk assessment under the current legal system. A few items were suggested to be included in the exposure assessment result reporting to be accepted as risk assessment. A pilot study in two small factories was performed and pointed out the strengths and weakness of our suggestions. Conclusions: Discussions and studies on the improvement of the exposure assessment system have been held for decades and no tangible changes have yet been made. We hope this result can help realize healthy lives for workers in Korea.

In the risk assessment of chemical substances, aggregation of exposure to a substance from different sources via different pathways is not common practice. Focusing the exposure assessment on a substance from a single source can lead to a significant underestimation of the risk. To gain more insight on how to perform an aggregate exposure assessment, we applied a deterministic (tier 1) and a person-oriented probabilistic approach (tier 2) for exposure to the four most common parabens through personal care products in children between 0 and 3 years old. Following a deterministic approach, a worst-case exposure estimate is calculated for methyl-, ethyl-, propyl- and butylparaben. As an illustration for risk assessment, Margins of Exposure (MoE) are calculated. These are 991 and 4966 for methyl- and ethylparaben, and 8 and 10 for propyl- and butylparaben, respectively. In tier 2, more detailed information on product use has been obtained from a small survey on product use of consumers. A probabilistic exposure assessment is performed to estimate the variability and uncertainty of exposure in a population. Results show that the internal exposure for each paraben is below the level determined in tier 1. However, for propyl- and butylparaben, the percentile of the population with an exposure probability above the assumed “safe” MoE of 100, is 13% and 7%, respectively. In conclusion, a tier 1 approach can be performed using simple equations and default point estimates, and serves as a starting point for exposure and risk assessment. If refinement is warranted, the more data demanding person-oriented probabilistic approach should be used. This probabilistic approach results in a more realistic exposure estimate, including the uncertainty, and allows determining the main drivers of exposure. Furthermore, it allows to estimate the percentage of the population for which the exposure is likely to be above a specific value.

Exposure and risk assessment can be based on direct epidemiological investigations that study exposed individuals or on models. Examples from situations in Germany for both approaches are presented and discussed here. Epidemiological studies for the health risk assessment of contaminated soil typically have one or more of the following problems: the number of exposed persons is too small: critical confounders cannot be measured and controlled for appropriately; or the expected effects are not large enough to be detected. Therefore, at least for most situations in Germany, epidemiological investigations designed to measure health risks infrequently provide clear answers. In contrast, direct epidemiological investigations are more likely to be able to quantify exposure. If the soil concentrations are high, one is able to identify the location of relevant “hot spots” using biological and environmental monitoring. Further, epidemiology can be used to get information about the distribution of exposure in specific populations, such as young children or amateur gardeners. Exposure assessment by modeling provides answers in situations in which no reasonable answers can be expected using epidemiological means. The model gives quantitative estimates for average and reasonable worst-case situations. The latter can be determined by modeling probability distributions.

Chapter 29 - Risk Assessment

The occupational hazard assessment of construction project implemented currently in China plays an important role in early prevention of occupational diseases. But the assessment techniques and methods are mostly based on qualitative mode or experience mode. There are still not unified and clear assessment methods and quantitative models to evaluate the chronic and potential cancer risk of chemicals. Because of the lack of scientific quantitative assessment methods, the risk can not be assessed quantitatively and scientifically. That also turns to be one of the technical difficulties demanding prompt solution in occupational hazards assessment. This paper introduced the risk assessment technique based on Monte Carlo simulation and dose-response multistage model. This method regarded the probabilistic risk of cancer as assessment target, and mainly used in quantitative assessment of cancer risk caused by chronic exposed to chemical carcinogens. The widely adopted four-step assessment method was used in health risk assessment, and it included hazard identification, dose-response assessment, exposure assessment and risk characterization. We used internal dose instead of external dose in assessment, and it made the result more accurate. The relationship between exposure dose and adverse health effect is determined by multistage model. For the uncertainty in exposure and risk assessment, we use Monte Carlo simulation to analyze the probability distribution. This method can be used practically in occupational hazards assessment and provide a scientific basis to the control of occupational hazards and the prevention and management of occupational tumor and other serious occupational diseases.

Food safety is important not only for the people’s general health and daily life, economic development, and social stability but also for the government’s and country’s image. Microbiological and chemical contamination in food is a major cause of illnesses. Food-borne disease remains a real and formidable problem in both developed and developing countries, causing great human suffering and significant economic losses. New science-based approaches to food safety provide an effective way for governments to protect consumers against food-borne disease and plan appropriate response measures when necessary. Risk assessment is a structured science-based process to estimate the likelihood and severity of risk with attendant uncertainty. For risk assessment many organizations recognize four major elements: hazard identification; exposure assessment; dose–response assessment or hazard characterization; and risk characterization. Risk assessment can be descriptive or narrative, qualitative, semi-quantitative, or quantitative. Both qualitative and quantitative risk assessments are important in different circumstances. Food safety risk assessments are undertaken in response to identified chemical or microbial risks to human health. Chemical risk assessments focus on the presence of chemicals such as food additives, food contaminants, or residues of veterinary drugs. A microbial risk assessment evaluates the likelihood of adverse human health effects occurring after exposure to a pathogenic microorganism or to the medium in which the organism occurs. Activities within risk assessment focus on estimating the risk that a hazardous event or factor will negatively affect a population or subpopulation. This chapter deals with the food safety risk assessment process. It introduces a range of techniques that can be used to support risk assessment in practice and outlines the essential characteristics of a good risk assessment.

Foodborne Microbial Pathogens in World Trade: Foodborne microbial pathogens Chronic sequelae following foodborne illness Emergence and re--emergence of foodborne pathogens and toxins Changes in host susceptibility and exposure Processing methods and globalisation of the food industry Changes in consumption pattern Immunological status Malnutrition Changing perceptions and values Risk of food poisoning The cost of foodborne diseases International control of microbiological hazards in foods Sanitary and Phytosanitary (SPS) Agreement Origin of microbiological risk assessment. Food Safety, Control and HACCP: Outline of HACCP Food hazards Pre--HACCP Principles Principle 1 Hazard Analysis Principle 2 Critical Control Points Principle 3 Critical Limits Principle 4 CCP Monitoring Principle 5 Corrective Actions Principle 6 Verification Principle 7 Record--keeping Control at source Product design and process control Intrinsic and extrinsic factors affecting microbial growth Irradiation High Pressure Technology Temperature control of microbiological hazards Microbial response to stress Response to pH stress Heat-- and cold shock response Response to osmotic shock Response to high hydrostatic pressure Predictive modelling Primary models and the Gompertz and Baranyi equations Secondary models Tertiary models Microbiological Criteria Attributes sampling plan Operating characterisitic curve. Risk Analysis: Overview of Microbiological Risk Assessment Risk Assessment Risk Management Risk Communication Risk Assessment Statement of purpose Hazard Identification Exposure Assessment Hazard Characterization Preface Dose--response assessment Dose--response models Dose and infection Risk Characterization Production of a formal report Triangular distributions and Monte Carlo simulation Risk Management Risk assessment policy Risk Profiling Food Safety Objectives Risk Communication. Application of Microbiological Risk Assessment: Salmonella spp. S. Enteritidis in shell eggs and egg products Hazard identification and hazard characterization of Salmonella in broilers and eggs Exposure assessment of Salmonella Enteritidis in eggs Exposure assessment of Salmonella spp. in broilers Salmonella spp. in cooked chicken Salmonella spp. in cooked patty Poultry FARM Domestic and sporadic human salmonellosis Campylobacter jejuni/coli jejuni risk from fresh chicken Risk profile for pathogenic species of Campylobacter in Denmark Risk assessment of C. jejuni in broilers Campylobacter fluoroquinolone resistance Listeria monocytogenes L. monocytogenes hazard identification and hazard characterization in ready--to--eat foods L. monocytogenes exposure assessment in ready--to--eat foods Relative risk of L. monocytogenes in selected ready--to--eat foods L. monocytogenes in EU trade L. monocytogenes in meat balls Enterohaemorrhagic E. coli (EHEC) E. coli O157:H7 E. coli O157:H7 in ground beef Bacillus cereus cereus risk assessment Vibrio parahaemolyticus Public health impact of V. parahaemolyticus in raw molluscan shellfish Mycotoxins Aflatoxins Ochratoxins Other mycotoxins Rotaviruses Viral contamination of shellfish and coastal waters. Future Developments in Microbiological Risk Assessment: International methodology and guidelines Data Training courses and use of resources Microbiological risk assessment support system Glossary of terms used in risk analysis References Internet directory Index

Chapter Eight - Examples of Risk Assessments of Human Metal Exposures and the Need for Mode of Action (MOA), Toxicokinetic-Toxicodynamic (TKTD) Modeling, and Adverse Outcome Pathways (AOPs)

Poor air quality is a leading contributor to the global disease burden and total number of deaths worldwide. Humans spend most of their time in built environments where the majority of the inhalation exposure occurs. Indoor Air Quality (IAQ) is challenged by outdoor air pollution entering indoors through ventilation and infiltration and by indoor emission sources. The aim of this study was to understand the current knowledge level and gaps regarding effective approaches to improve IAQ. Emission regulations currently focus on outdoor emissions, whereas quantitative understanding of emissions from indoor sources is generally lacking. Therefore, specific indoor sources need to be identified, characterized, and quantified according to their environmental and human health impact. The emission sources should be stored in terms of relevant metrics and statistics in an easily accessible format that is applicable for source specific exposure assessment by using mathematical mass balance modelings. This forms a foundation for comprehensive risk assessment and efficient interventions. For such a general exposure assessment model we need 1) systematic methods for indoor aerosol emission source assessment, 2) source emission documentation in terms of relevant a) aerosol metrics and b) biological metrics, 3) default model parameterization for predictive exposure modeling, 4) other needs related to aerosol characterization techniques and modeling methods. Such a general exposure assessment model can be applicable for private, public, and occupational indoor exposure assessment, making it a valuable tool for public health professionals, product safety designers, industrial hygienists, building scientists, and environmental consultants working in the field of IAQ and health.

Use of Exposure Data for Risk assessment

Risk assessment. Ecological

Risk assessment of contact allergens

Chapter 31 - Risk Assessment