Health risk assessment biomarkers

There is a growing need to better characterize the health risk related to occupational and environmental exposure to pesticides. Risk characterization is a basic step in the assessment and management of the health risks related to chemicals (Tordoir and Maroni, 1994). Evaluation of exposure, which may be performed through environmental and biological monitoring, is a fundamental component of risk assessment. Biomarkers are useful tools that may be used in risk assessment to confirm exposure or to quantify it by estimating the internal dose. Besides their use in risk assessment, biomarkers also represent a fundamental tool to improve the effectiveness of medical and epidemiological surveillance. 

As was mentioned in the previous section, HPLC-MS is widely used for the determination of biomarkers. Three specific applications of biomaiker analysis using HPLC-MS are described in additional detail they are acrylamide, common aromatic compounds such as toluene and benzene, and, finally, 1-bromopropane. These are common compounds found in general and work environments and are of interest for human exposure studies and health risk assessment. 

This chapter s characterization of lead as a neurotoxic hazard does not include detailed dose—response relationships with various levels of biomarkers such as PbB linked to various neurotoxic outcomes. The topics of dose/ exposure metrics and defining full-spectrum dose—response relationships are presented in the next part, the section dealing with the elements of human health risk assessment for environmental lead. Here, for ease of discussion, only a broad yardstick is provided for toxic lead exposures. Specifically, general PbB ranges associated with the various categories of lead neurotoxicity, especially in children, are noted. 

There is a continuing interest in the development of biomarker assays for use in environmental risk assessment. As discussed elsewhere (Section 16.6), there are both scientific and ethical reasons for seeking to introduce in vitro assays into protocols for the regulatory testing of chemicals. Animal welfare organizations would like to see the replacement of toxicity tests by more animal-friendly alternatives for all types of risk assessment—whether for environmental risks or for human health. 

Kreps SE, BanzetN, Christiani DC, Polla BS. 1997. Molecular biomarkers of early responses to environmental stressors — implications for risk assessment and pubhc health. Rev Environ Health 12 261-280. 

Effects produced by exposure to acrylonitrile, particularly after acute exposures, are characteristic of cyanide toxicity. These effects can be detected in people exposed by evaluating signs and symptoms such as limb weakness, labored and irregular breathing, dizziness and impaired judgement, cyanosis and convulsions. While tests are not specific for acrylonitrile-induced toxicity, they do identify potential health impairment. Studies to develop more specific biomarkers of acrylonitrile-induced effects would be useful in assessing the potential health risk of acrylonitrile near hazardous waste sites. 

NOMIRACLE (2004-2009, http //viso.jrc.it/nomiracle/) provided support to the development and improvement of a coherent series of methodologies underpinned by mechanistic understanding, while integrating the risk analysis approaches of environmental and human health. The project delivered understanding of and tools for sound risk assessment, developing a research framework for the description and interpretation of combined stressor effects that leads to the identification of biomarkers and other indicators of cumulative impacts. 

The most important question for biomonitoring efforts to address is whether exposure to a chemical causes health effects. Few data are available on most of the chemicals measured in population studies, such as NHANES, to address that question (Metcalf and Orloff 2004). For example, the Government Accountability Office (GAO 2005) reports that EPA has limited data on the health and environmental risks posed by chemicals now used in commerce. A survey of risk-assessment practitioners on the extent to which biomarkers are used in risk assessment concluded that the absence of chemical-specific data (for example, toxicologic and epidemiologic data) was the primary limitation in using exposure biomarkers in risk assessment (Maier et al. 2004). 

WHO (World Health Organization). 2001. Biomarkers in Risk Assessment Validity and Validation. Environmental Health Criteria 222. Geneva World Health Organization. 238pp [online]. Available http //www.inchem.org/documents/ehc/ehc/ehc222.htm [accessed Nov. 21, 2005]. 

All those activities have specific purposes and may be conducted alone (for example, for priority-setting among public-health actions) or as parts of a multitier strategy. Links between risk-assessment and -management activities (why biomonitoring is conducted) and the properties of the biomarkers (what characteristics our biomonitoring tools need to have for us to be able to conduct these activities) will be presented below. 

IPCS (1993) Biomarkers and risk assessment concepts and principles. Geneva, World Health Organization, International Programme on Chemical Safety (Environmental Health Criteria 155). 

Hutchinson TH, Ankley GT, Segner H, Tyler CR. 2006. Screening and testing for endocrine disruption in fish — biomarkers as signposts not traffic lights in risk assessment. Environ Health Perspect 114 106-114. 

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