When asked to determine the health consequences of past exposures to a chemical we perform a retrospective exposure study for an individual, or group. This typically has several components.
In the first instance, exposures historically experienced by an individual in an occupation or while performing a task may have been studied, and have been described in papers and journal articles. Finding appropriate studies requires a literature search and review. As sampling and analytical methods have developed and changed over time, it is sometimes necessary to account for these changes when assessing an exposure, or cumulative dose.
In some instances, where a particular exposure has not been studied, it is useful to perform an exposure study by measuring exposures as a task is performed. Care must be taken to avoid problems such as sampler overload, and to use sampling and analytical technologies that permit comparison to other exposures.
Once exposures for each task, or occupation are determined, and the duration of such activities are known, a lifetime exposure, or dose for an individual or group can be estimated. This permits an analysis of comparative risks to be made, such as the risk due to background levels of chemicals found in the ambient environment, and other commonly accepted risks, such as automotive travel and eating processed foods.
Retrospective exposure studies can be useful in assessing the health consequences for past exposures, to predict future exposures, and to determine the level of personal protective equipment necessary to maintain lifetime exposures at an acceptable level.
Here are some examples of past projects that illustrate our approach.