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Environmental hazard identification
(NOTE: this will be a subsection within “Environmental hazard” and possibly also the "Occupational hazard" Wikipedia pages)

Environmental hazard identification is the first step in environmental risk assessment, which is the process of assessing the likelihood, or risk, of adverse effects resulting from a given environmental stressor. Hazard identification is the determination of whether, and under what conditions, a given environmental stressor has the potential to cause harm.

In hazard identification, sources of data on the risks associated with prospective hazards are identified. For instance, if a site is known to be contaminated with a variety of industrial pollutants, hazard identification will determine which of these chemicals could result in adverse human health effects, and what effects they could cause. Risk assessors rely on both laboratory (e.g., toxicological) and epidemiological data to make these determinations.

Conceptual model of exposure
Hazards have the potential to cause adverse effects only if they come into contact with populations that may be harmed. For this reason, hazard identification includes the development of a conceptual model of exposure. Conceptual models communicate the pathway connecting sources of a given hazard to the potentially exposed population(s). The U.S. Agency for Toxic Substances and Disease Registry establishes five elements that should be included in a conceptual model of exposure:


 * The source of the hazard in question
 * Environmental fate and transport, or how the hazard moves and changes in the environment after its release
 * Exposure point or area, or the place at which an exposed person comes into contact with the hazard
 * Exposure route, or the manner by which an exposed person comes into contact with the hazard (e.g., orally, dermally, or by inhalation)
 * Potentially exposed populations.

Evaluating hazard data
Once a conceptual model of exposure is developed for a given hazard, measurements should be taken to determine the presence and quantity of the hazard. These measurements should be compared to appropriate reference levels to determine whether a hazard exists. For instance, if arsenic is detected in tap water from a given well, the detected concentrations should be compared with regulatory thresholds for allowable levels of arsenic in drinking water. If the detected levels are consistently lower than these limits, arsenic may not be a chemical of potential concern for the purposes of this risk assessment. When interpreting hazard data, risk assessors must consider the sensitivity of the instrument and method used to take these measurements, including any relevant detection limits (i.e., the lowest level of a given substance that an instrument or method is capable of detecting).