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Maine people are polluted with phthalates. All 25 people tested in our study had detectable levels of phthalates in their bodies, with total phthalate exposure ranging from 46 parts per billion (ppb) to 763 ppb. We measured nine metabolites (or breakdown products) in urine that represent recent exposure to seven phthalates. At least six of nine metabolites were measured in every person, while eight Mainers had all nine phthalate metabolites in their bodies and another 13 were exposed to eight of the nine chemicals. For the methods used, see Appendix A. For the full results, see Appendix B.

Figure 1. Mainers Face Cumulative Exposure to Phthalates

Cumulative exposure to multiple phthalates has an additive effect on the risk to human health. That’s why it’s important to consider total phthalate exposure, as in Figure 1. Each bar on the graph represents recent exposure to the phthalates tested for in the person named. The Maine results are comparable to exposures for all Americans measured by the CDC’s national biomonitoring program. The red lines mark the percentile exposure for the U.S. population, age 20 and older, in 2010. For example, 10% of Americans were exposed to phthalates at a level greater than 744 parts per billion (top red line, 90th percentile). Two other red lines show American exposure at the 75th percentile (at 287 ppb) and 50th percentile (123 ppb).

Figure 2. Some Mainers are More Highly Exposed to Phthalates than Other Americans

Figure 2 shows the number of Mainers that were exposed to specific phthalates above the national norm. The Maine group was exposed to higher levels of three phthalates (DIDP, DIBP, DEHP) than all other Americans, and to lower levels of two others (DEP, DINP). Eight Mainers were in the top 5% of U.S. exposures for five phthalates, including two people for two phthalates each. The exposure levels for another four people tested were in the top 10% for all Americans.

The DIDP exposure levels in Mainers were much higher than for other Americans for every percentile. A “percentile” represents the proportion of people exposed above and below a specific exposure level. For example, 5% of all Americans are exposed to more than the chemical concentration representing the 95th percentile, while 95% of the U.S. population is exposed less than that. Similarly, the 50th percentile represents the midway point in the exposure range, with half of Americans exposed at a higher level and half exposed lower. If the phthalate exposure pattern for the 25 Mainers matched the national profile, we would expect the number of people exposed to be close to the red bars in Figure 2 for each percentile.

The higher levels of DIDP in Mainers might reflect increased use of that phthalate as a DEHP replacement since the U.S. data were obtained by the CDC in 2010, rather than real disproportionate exposure. A continued downward trend might also explain the lower DEP test results, although it is possible that this Maine group also avoids synthetic fragrances containing DEP more often.

Figure 3. The Phthalates and Their Metabolites in the Maine Biomonitoring Survey

• A fourth DEHP metabolite was measured but not reported: MECPP, Mono-(2-ethyl-5-carboxypentyl) phthalate

• A second DINP metabolite was not measured by the laboratory: MINP, Mono-isononyl phthalate

• The Chemical Abstract Service (CAS) Registration Number uniquely identifies chemical compounds regardless of name

Figure 4. These Maine People were Exposed to Higher Levels of Phthalates than Most Americans

Exposure Notes: Urinary levels of metabolites reflect recent exposure to the parent phthalate compound. The percentiles of top US phthalate exposures are for adults 20 years and older from the 2010 CDC national biomonitoring survey. Actual BBP levels were somewhat higher than reported, and the DBP levels were somewhat lower. That’s because they share a common metabolite, MBP, all of which was assigned to DBP in the absence of data on how the MMP metabolite actually fractionates from the two parents. DEHP was also under-reported, because the results for a fourth DEHP metabolite known as MECPP were not reported because the laboratory "was not able to verify with a 3rd party confirmation." Similar levels of exposure to different metabolites may not represent the same level exposure to the parent phthalates, because each compound is metabolized at different rates and in varied proportions.


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