Health risk assessments

Since 1970 the field of healtli risk assessment lias received widespread attention within both the scientific and regulatory communities. It has also attracted the attention of the public. Properly conducted risk assessments liave received fairly broad acceptance, in part because tliey put into perspective the terms toxic, liazard, and risk. Toxicity is an inlierent property of all substances. It stales lliat all chemiciil tmd physical agents can produce adverse healtli effects at some dose or under specific exposure conditions. In contrast, exposure to a chemical tliat lias die capacity to produce a particular type of adverse effect, represents a healdi hazard. Risk, however, is die probability or likelihood tliat an adverse outcome will occur in a person or a group diat is exposed to a particular concentration or dose of the hazardous agent. Tlierefore, risk is generally a function of exposure and dose. Consequently, healdi risk assessment can be defined as the process or procedure used to estimate die likelihood diat humans or ecological systems will be adversely affected by a chemical or physical agent under a specific set of conditions. 

In terms of the contents of Part 111, Cliapter 9 serves to introduce die general subject of healdi risk assessment (HRA). An e, panded presentation on each of die four healdi risk assessment steps follows, as detailed below  

Cliapter 10 Healdi Hazard Ideiidfication Cliapter II Dose-respoiise/Toxicity Assessment Cliapter 12 Exposure Assessment Cliapter 13 Risk Analysis and Characterization 

The reader should note diat two general types of potential healdi risk exist. These are classified as  

Exposures occur for relatively short periods of time, generally from minutes to one to two days. Concentrations of (toxic) air contaminants are usually Iiigli relative to dieir protection criteria. In addition to iiilialation, airborne substances might directly contact die skin, or liquids and sludges may be splashed on die skin or into die eyes, leading to adverse healdi effects. This subject area falls, in a general sense, in die domain of hazard risk assessment (HZRA) and is addressed in die next two Parts (IV and V) of tills book. 

Chronic. Continuous exposure occurs over long periods of time, generally several mondis to years. Concentradons of inlialed (toxic) contaminants are usually reladvely low. This subject area falls in die general domain of healdi risk assessment (HRA) and it is diis subject tliat is addressed in die next five chapters. Thus, in contrast to the acute (short-tenn) exposures diat predominate in hazard risk assessments, clironic (long-tenn) exposures are the major concern in health risk assessments. 

Most human or environmental healtli hazards can be evaluated by dissecting tlie analysis into four parts liazard identification, dose-response assessment or hazard assessment, exposure assessment, and risk characterization. For some perceived healtli liazards, tlie risk assessment might stop with tlie first step, liazard identification, if no adverse effect is identified or if an agency elects to take regulatory action witliout furtlier analysis. Regarding liazard identification, a hazard is defined as a toxic agent or a set of conditions that luis the potential to cause adverse effects to hmnan health or tlie environment. Healtli hazard identification involves an evaluation of various forms of information in order to identify the different liaz.ards. Dose-response or toxicity assessment is required in an overall assessment responses/cffects can vary widely since all chemicals and contaminants vary in their capacity to cause adverse effects. This step frequently requires that assumptions be made to relate 

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L. P. Brown, D. G. Earrar, and C. G. DeRooij, Health Risk Assessment of Environmental Exposure to Trichloroethylene, Regulatory, Toxicol Pharmacol 11, 24-41 (1990). 

In recent years, several guidelines and handbooks have been produced to help e.xplain approaches for doing health risk assessments. As discussed by a special National Academy of Sciences committee convened in 1983, most... 

What arc the general duties of state, territorial, and local air pollution control agencies as they relate to health risk assessments ... 

What is the role of liiiinan health risk assessment in risk manageinent ... 

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 ... 

What arc some of the important complications in the "hazard identification step of the health risk assessment process ... 

Health risk assessment is defined as Uie process or procedure used to estimate Uie likelihood that humans or ecological systems will be adversely affected by a chemical or physical agent under a specific set of conditions. 

List tire four main components of health risk assessment and explain them briefly. 

Exposure is defined as llie contact of an organism (hmnans in llie case of health risk assessment) with a chemical or physical agent (3). 

In health risk assessments, non carcinogenic risks are estimated via Hazard Indices . A general equation for a liazard index (HI) is as follows ... 

In health risk assessment, the carcinogenic risk calculation by inhalation (IR) can be calculated by ... 

RIVM (2000) Health risk assessment for organotins in textiles. Bilthoven, Dutch National Institute for Public Health and the Environment, January (RIVM Report No. 613350 002). 

Bames DG, Dourson M. 1988. Reference dose (RfD) description and use in health risk assessments. Regul Toxicol Pharmacol 8 471-486. 

EPA. 1988d. Reference dose (RfD) Description and use in health risk assessment. Vol. I, Appendix A Integrated risk information system supportive documentation. U.S. Environmental Protection Agency, Office of Health and Environmental Assessment. EPA 600/8-86-032a. 

Lohman PHM. 1999. Qualitative and quantitative procedures for health risk assessment. Mutat Res 428 237-254. 

Abelson PH. 1993. Health risk assessment. Regul Toxicol Pharmacol 17 219-223. 

Bogen KT, Hall LC, Perry L, et al. 1988. Health risk assessment of trichloroethylene (TCE) in California drinking water. Livermore, CA University of California, Lawrence Livermore National Laboratory, Environmental Sciences Division. NTIS No. DE88-005364. 

Brown LP, Farrar DG, de Rooij CG. 1990. Health risk assessment of environmental exposure to trichloroethylene. Regul Toxicol Pharmacol 11 24-41. 

Fan AM. 1988. Trichloroethylene Water contamination and health risk assessment. Rev Environ Contam Toxicol 101 55-92. 

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

Envlroiunental testing Is a critical element In this process since It enables the qualitative and quantitative determination of toxic chemicals In the environment and the definition of environmental pathways which may lead to human exposure This paper briefly reviews the overall process of health risk assessments and the particular role which environmental testing plays Recent efforts to assess environmental health risks In relation to Love Canal Illustrate both the usefulness and the limitations of environmental testing In risk assessment ... 

High hazard material - selection of lower hazard material recommended if I substitution is not feasible perform health risk assessment and adopt exposure control strategy to reduce health risks... 

Hazard material perform health risk assessment and adopt exposure control strategy to reduce health risks... 

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). 

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