Author: Muhammad Ahmad

The concept of de manifestis risk is not controversial because some effects are clearly unacceptable. However, the idea that some exposures to and effects of pollutants are acceptable (de minimis) is controversial. The use of the de minimis concept is based on the following considerations: Since we cannot prevent all human effects on the environment,…

Those charged with risk management for human health are fully aware that some risks have consequences so dire that they must be avoided no matter what the cost. Risks so obviously unacceptable are called de manifestis. The companion concept, de minimis, which we shall explore shortly, points to the existence of risks with consequences so…

Determining risk severity is one of a risk manager’s first tasks. On this basis, he or she must decide whether a given risk is unacceptable, hence must be reduced or prevented with monitoring, or can be accepted, at least for the present. The risks associated with possible alternatives must be considered, as well. For example,…

Risk management, the process of decision‐making that attempts to minimize risks without undue harm to other societal values, should be performed independently of risk analysis (NRC 1983). Since, however, the effectiveness of a risk analysis depends on the successful interaction of the risk analyst and the risk manager, we discuss risk management briefly. The risk analysts do…

Ozone is formed in the troposphere when sunlight causes complex photochemical reactions involving oxides of nitrogen (NOx), and VOCs that originate chiefly from gasoline engines and burning of other fossil fuels. Woody vegetation is another major source of VOCs (e.g. isoprene or terpene, formaldehyde, acetaldehyde, methyl‐ethyl‐ketone, acetone, etc.). NOx and VOCs can be transported long distances…

Sampling and Surveys Although general sampling issues will have necessarily been addressed before the ERA reached the effects assessment stage, it is worthwhile to note a few of them here. This will ensure that the risk assessor has mentioned and considered the potential impacts of these issues. Field surveys and ambient media chemical analyses are…

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…

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…

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…

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…