Category: Assessment And Management Of Health And Environmental Risks

An ecological effects assessment includes a description of ecotoxicological benchmarks used in the assessment, toxicity profiles for contaminants of concern, and results of the field sampling efforts. The field data may include field survey information and toxicity test results. Ecotoxicological benchmarks represent concentrations of chemicals in environmental media (i.e. water, soil, sediment, biota) that are… Continue reading Ecological Effects Assessment

ERA has several considerations that HHRA lacks. One of the most important factors affecting the exposure assessment is the spatial and temporal scale of the assessment. Spatially, exposure estimates must take into account the home range of, and the availability of, suitable habitat for the receptor species, relative to the areal extent of contamination. Temporal… Continue reading Ecological Exposure Assessment

Determining how many data are needed to address the ERA goals is part of the process of meeting a project’s Data Quality Objective (DQO). All risk assessment stakeholders (e.g. the US EPA, the State, the Fish and Wildlife Service, etc.) should be involved in this process. The DQO is ascertained at the beginning of an… Continue reading Technical Aspects of Ecological Problem Formulation

The four major components of the ERA paradigm are problem formulation, exposure assessment, effects assessment, and risk characterization (Anderson and Albert 1998; Suter et al. 2000; USEPA 1992, 1997, 1998a). An ERA begins with problem formulation. Activities occurring during this phase include definition of the goals and spatial and temporal scale of the ERA, development of a SCM, selection of… Continue reading Ecological Risk Assessment

Particulate matter (PM) is the general term for microscopic solid or liquid phase (aerosol) particles suspended in air. PM exists in a variety of sizes, with diameters ranging from a few angstrom units to several hundred micrometers. Particles are either emitted directly from primary sources or are formed in the atmosphere by gas‐phase reactions (secondary… Continue reading Particulate Matter

Carbon monoxide (CO) is a colorless, odorless gas formed primarily as a by‐product of incomplete combustion. The major health hazard posed by CO is its capacity to bind with hemoglobin in the blood stream and thereby reduce the oxygen‐carrying ability of the blood. Transportation sources account for the bulk (76.6%) of total national CO emissions.… Continue reading  Carbon Monoxide

Risk assessment is built on the principle that small exposures carry with them some risk of an untoward health effect such as development of a malignant tumor or leukemia at some time in the future. Such risks are generally considered to be stochastic or probabilistic in nature and are expressed in terms of a risk… Continue reading Assessing the Risks of Some Common Pollutants

The final stage of a four‐stage human health risk assessment is to estimate risks. Cancer is not the only undesired health consequence of pollution: exposure to ionizing radiation and coal dust, for example, can lead to radiation sickness and birth defects, as well as cancer. To illustrate risk characterization; however, we shall focus on the… Continue reading Risk Characterization

Broadly speaking, toxicity is the degree to which a substance is poisonous. Most chemicals, toxic or otherwise, enter the body through eyes, respiratory tract, digestive tract, and skin. Two levels of toxicity are defined: acute “short‐term” exposure that initiates poisoning and chronic “long‐period” exposure that causes anemia, leukemia, and death. In the context of the third… Continue reading Toxicity Assessment

In mechanistic models, it is assumed that a certain number of reactions, events, or “hits” (concept derived from radiation biology), or transition stages, related to a critical target in the cell (DNA), are necessary to transform a normal cell to a cancer cell. These models are important because there seems to be general consensus that… Continue reading Mechanistic Models