Risk assessment human health

Results from the risk assessment are used to inform risk management. The risk manager uses the risk information in conjunction with factors such as the social importance of the risk, the social acceptability of the risk, the economic impacts of risk reduction, engineering, and legislative mandates when deciding on and implementing risk management approaches. 

The risk assessment may be perceived as the source of a risk management decision, when in fact, social concerns, international issues, trade, public perception, or other non-risk considerations may be taken into consideration. Finally there is one activity known as risk communication that involves making the risk assessment and risk 

A Textbook of Modern Toxicology, Third Edition, edited by Ernest Hodgson ISBN 0-471-26508-X Copyright 2004 John Wiley Sons, Inc. 

Nature of effects Potency of agent Exposure Population at risk Average risk High-end risk Sensitive groups Uncertainties of science Uncertainties of analysis Identify Describe Measure 

Bioavailability is assessed in a different way for human health when compared to approaches used for ecosystems. 

However, for exposure through soil ingestion (e.g., a child who ingests 5 g of soil per day or for soil clinging to root crops), there is not only bioavailability of a substance in soil to consider but also the differences between intake (i.e ingestion of substances via soil particles into the human body) and uptake (i.e., absorption of a substance into the blood and, hence, effects on a target organ). Three steps are involved in this process  

1) Bioaccessability (e.g., release of the substance from the soil particles in the stomach). 

3) Passage to and targeting of a specific organ, such as the liver. The difference between uptake and intake is expressed by the so-called relative bioavailability factor (Oomen et al. 2006). 

While public perception of risk is sometimes frustrating to expert risk assessors, it can serve a useful purpose by focusing attention on catastrophic risks that impact whole communities, not just individuals. The risk of a meltdown at a nuclear power plant is small, but the consequences are huge Witness Chernobyl and the continuing effects of radioactive contamination. In the difficult political business of managing risks, risk perception can complement expert risk assessment and help drive the regulatory process forward. 

Essentials of Toxic Chemical Risk Science and Society 

Selected Examples of Differences Between Expert and Lay Perceptions of Risk 

Source Reprinted with permission from Mary Amdur,  

Note Nuclear power was ranked 1 on the lay list and 20 by experts. The rankings are from 1979. 

As we have seen, there are a great variety of situations for which risk assessment can be applied. Regardless of the situation, however, the goals and objectives of a risk assessment are generally the same to identify if either (1) an area containing chemicals may be toxic to humans, or (2) a specific chemical is toxic, and if so, at what concentration. If a chemical might be toxic at the levels present at a site, then a third goal would be to identify how much cleanup is necessary to protect human health. 

The standardized human health risk assessment methodology generally includes the following four components  

Data evaluation Exposure assessment Toxicity assessment Risk characterization 

An overview of the methodology cmd the interconnections cimong the components is shown on figure 8.1. In data evaluation, the conditions at the site cire identified. In this step, we use information about the chemicals present at the site to identify concentrations to which we could be exposed and the spatial extent of contamination. In exposure assessment, we identify how humans could contact chemicals, and estimate possible doses resulting from cissumed levels of exposure. This includes identifying the types of people that could be exposed, cmd by what routes they could be exposed (e.g., ingestion, inhalation). For example, would someone be exposed to lead if it was buried in soil under concrete If the impacted area were an active industrial facility, would you assume children could be exposed In toxicity assess- 

The objective of the data evaduation component of a human health risk assessment is to define the nature and extent of chemical contamination at a site. This could include taking soil and/or groundwater samples to identify what chemicals are present, where they are present, and at what concentrations. This information provides the foundation for the risk assessment. 

The dangerous properties of acute toxicity, irritation, corrosivity, sensitisation, repeated-dose toxicity and CMR are evaluated in terms of their potential toxic effects to workers, consumers and man exposed indirectly via the environment, based on the use for each stage in the lifecycle of the substance from which exposure can occur. Risk assessment is also required if there are reasonable grounds for concern for potential hazardous properties, e.g., from positive in vitro mutagenicity tests or structural alerts. The risk assessment involves comparing the estimated occupational or consumer exposure levels with the exposure levels at which no adverse effects are anticipated. This may be a quantitative risk assessment, based on the ratio between the two values, or a qualitative evaluation. The principles of human health risk assessment are covered in detail by Illing (a.30) and more briefly in Chapter 7 of (73). 

Many toxic effects are not expressed until the amount of the chemical, or a toxic metabolite, in the target tissue reaches a threshold concentration. Whether or 

For acute toxicity, corrosivity and skin and eye irritation, values for the NOEL (or NOAEL or LOAEL) are not derived. Therefore, the only option is to determine whether the substance has an inherent capacity to cause such effects and to make a qualitative risk assessment to evaluate the likelihood of an adverse effect occurring in use. 

Mutagenicity and carcinogenicity are generally considered to be non-threshold effects, unless a non-genotoxic mechanism can be established with a NOEL (or NOAEL or LOAEL). Risk assessment is based on establishing whether exposure is prevented. A similar process of preventing exposure also applies for skin and respiratory sensitisers, since there is no means of identifying a dose or concentration below which adverse effects will not occur in someone already sensitised to a particular substance. 

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Human health risk assessment estimates the likelihood of health problems occurring if no cleanup action were ttikcn at the site. To cstiimite the baseline risk at a site, the following four-step process should be taken to detennine Uie possible human risk which will then detennine what sort of corrective action should be employed ... 

Uses of Environmental Testing in Human Health Risk Assessment... 

EPA (1989) indicated that actual doses could not be verified, considered the study inappropriate for human health risk assessment, and rejected it for use in the development of a hazard advisory. No mortality occurred and no toxic effects were noted in beagle dogs (4 per sex per dose group) that received diisopropyl methylphosphonate in the diet (0, 4, 38, or 75 mg/kg/day) for 13 weeks (Hart 1980). 

EPA (1989) also indicates that analysis of the diisopropyl methylphosphonate used in this study determined that it was only 65% pure. Therefore, results from the Army (1978) study are considered inappropriate for human health risk assessment. No deaths of adult rats were recorded in a three-generation study of reproductive effects in rats receiving diisopropyl methylphosphonate in the diet at 0, 30, or 300 mg/kg/day (Hart 1980). 

No differences were noted in the litter sizes among those treated and the controls. No differences were noted in the number of stillborn pups or in pup weights. The study authors concluded that there was no evidence of adverse diisopropyl methylphosphonate-induced reproductive effects. However, as discussed in Section 2.2.2.1, there is some confusion regarding the actual doses to which the animals were exposed in the Hardisty et al. (1977) study. Therefore, results from this study are considered inappropriate for human health risk assessment. 

Although none of the three laws or their implementing regulations directly addressed the reuse of waste materials, they necessitate a series of evaluations in the reuse program of solid waste, which include the preparation of an environmental assessment, a human health risk assessment, or an ecosystem risk assessment. 

This chapter considers the recently developed tools and the latest versions of the old tools. Some of the tools comprise not only the environmental compartments used on environmental risk assessment but also the human compartment necessary for human health risk assessment. For this reason, when summarizing the models, as described in the second part of this chapter, several characteristics of human compartment are discussed as well. However, a detailed description of human compartment together with a wide range of tools developed for exposure and human risk assessment is presented in the next chapter. 

Human Health Risk Assessment 3.1 Hazard Identification... 

For human health risk assessment, it is necessary to elaborate realistic scenarios. Knowledge of real scenarios where the contaminant is emitted to the environment will help to obtain information about the fate and transport of the contaminant once emitted to the environment and the route of exposure for the human beings living in this scenario of concern. There are different types of exposure, i.e., direct, indirect (as is the case of food contaminated by the air, water, or soil contaminated by the emission), occupational exposure, and consumer goods coming from outside the scenario of concern. Depending on the objective of the study, it will be necessary to consider in the exposure assessment one or more types of exposure. 

SADA provides a full human health risk assessment module and associated databases. The risk models follow the USEPA s Risk Assessment Guidance for Superfund (RAGS) and can be customized to fit site-specific exposure conditions. It calculates risks based on the following exposure pathways ingestion, inhalation, dermal contact, food consumption, and also a combined exposure. 

Analyst to conduct multipathway human health risk assessments and food-web based ecological risk assessment modeling. BREEZE risk analyst combines databases, GIS functionality, fate, transport, and exposure modeling equations into one software application... 

IRAP-h View Interface for conducting a comprehensive multipathway human health risk assessment. It simultaneously calculates risk values for multiple chemicals, from multiple sources, at multiple exposure locations. IRAP-h view implements the US EPA - OSW Human Health Risk Assessment Protocol (HHRAP) US EPA [15]... 

United States Environmental Protection Agency (2005) Human Health Risk Assessment Protocol (HHRAP) for Hazardous Waste Combustion Facilities (Final) EPA530-R-05-006 Office of Solid Waste. Washington, DC... 

Schwab BW, Hayes EP, Fiori JM, Mastrocco FJ, Roden NM, Cragin D, Meyerhoff RD, D Aco VJ, Anderson PD (2005) Human pharmaceuticals in US surface waters a human health risk assessment. Regul Toxicol Pharmacol 42 296—312... 

Sarlo, K., Human health risk assessment Focus on enzymes, In Proceedings of the 3rd World Conference on Detergents, Cahn, A., Ed., American Oil Chemists Society Press, Chicago, 1994, 54. 

US Environmental Protection Agency (2008) Human-Health Risk Assessment, EPA-HQ-OPP-2007-0535-0007. http //www.regulations.gov/ documentDetail D=EPA-HQ-OPP-2007-0535-0007. Accessed 14 Feb 2011... 

In broad terms risk assessments are carried out to examine the effects of an agent on humans (Health Risk Assessment) and ecosystems (Ecological Risk Assessment). Environmental Risk Assessment (ERA) is the examination of risks resulting from technology that threaten ecosystems, animals and people. It includes human health risk assessments, ecological or ecotoxicological risk assessments, and specific industrial applications of risk assessment that examine end-points in people, biota or ecosystems. 

Table 20. Typical assessment factors for human health risk assessment...

EPA (Environmental Protection Agency). 1998. Human Health Risk Assessment Protocol for Hazardous Waste Combustor Facilities, EPA 530-D-98-001, July. Washington, D.C. Environmental Protection Agency. 

The EPA does consider health criteria when determining whether to approve or deny a manufacturer s petition to have a tolerance established. Human health risk assessment practices consider potential human exposure from all registered (and proposed) uses of the pesticide, and if the risk is deemed excessive, the EPA will deny the tolerance petition. In cases where the risks are deemed acceptable, the EPA will establish tolerances, as described in the previous paragraphs. 

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