hygiene, occupational medicine, exposure assessment, risk assessment, and biostatistics. The committee was specifically asked to accomplish the following task:

An expert committee will assess the potential health risks to Department of Defense firing range instructors and other personnel who experience recurring environmental exposures to lead at small-arms firing ranges. Information will be evaluated on recurrent lead exposures at such firing ranges, and relevant toxicological and epidemiological information on any carcinogenic and non-carcinogenic effects of exposures to lead will be evaluated. The evaluated information will include reviews by the Environmental Protection Agency and the National Toxicology Program. The committee will assess whether current exposure standards used at ranges are protective and will evaluate potential risk assessment options.

APPROACH TO THE STUDY

There is a large amount of scientific literature on lead. To manage the amount of data that it had to review and to structure its analysis to address its task in a timely manner, the committee established the following boundaries for its review:

•  Evaluation of health effects. The committee did not conduct a systematic review of the lead literature or conduct a formal risk assessment, but it took advantage of the recent compilations of the toxicologic and epidemiologic studies of lead by the NTP, EPA, and the International Agency for Research on Cancer. Those reviews were used as a basis for identifying the primary health end points that would be of concern for firing-range personnel. The committee supplemented the reviews by evaluating relevant new studies related to those health effects and by determining what exposures would be of greatest concern. The following considerations were used to focus the committee’s review further:

image  Human studies were the primary source of data, and animal studies and mechanistic information were used when appropriate. Few epidemiologic studies of firing-range personnel were found; therefore, occupational and other studies involving lead exposure were sought. Studies that considered potential covariates in their statistical analyses were favored.

image  Acute, chronic, and latent health effects of lead exposure were considered. Data on clinical disease outcomes were believed to be more relevant to the committee’s charge than data on early biologic effects.

image  The preferred measures of exposure were the BLL as a measure of recent exposure and the cumulative blood lead index (CBLI) or bone lead concentrations as a measure of cumulative dose.

image  Health-effects data on BLLs under 40 μg/dL were considered primarily, because the current OSHA standard aims to maintain BLLs below



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