THE PRIORITY TOXICANT REFERENCE RANGE STUDY - INTERIM-REPORT

The relationship between human exposure to environmental toxicants and health effects is of utmost interest to public health scientists. To define this relationship, these scientists need accurate and precise m ethods for assessing human exposure and effects. One of the most accur ate and precise means of assessing exposure is to measure the level of the toxicant or its primary metabolite in a biologic specimen; this h as been defined as measuring the internal dose. This measurement must be quantitative to best study the dose-response relationship. Pertinen t questions asked during an exposure assessment include ''How do the l evels of a given toxicant in a particular population compare with the levels of that toxicant in other populations?'' and ''What is the prev alence of exposure to that toxicant in other populations!'' To answer these questions for two chemical classes of environmental toxicants, w e developed state-of-the-art analytic methods and then applied them to measure the levels of 44 environmental toxicants in biologic specimen s from 1000 United Stales residents who participated in the Third Nati onal Health and Nutrition Examination Survey (NHANES III). These 1000 people are a cross-sectional subset of the NHANES III population and w ere selected from urban and rural communities in four regions of the U nited States; ail were between 20 and 59 years of age. This subset is not a probability-based sample. The 44 environmental toxicants are 32 volatile organic compounds, which are measured at parts-per-trillion l evels in whole blood, and 11 phenols and one phenoxy acid, which are m easured at parts-per-billion levels in urine. We present statistical d ata for these toxicants in a large portion of our study's population. These analytic measurements have not been compared to any demographic characteristics, such as age and race, in this interim report. In addi tion, we also give examples of how the methods we developed and the re ference range data we gathered have been used to assess exposure in ot her populations.