PCDD/PCDF indoor exposure in day-care centers and PCDD/PCDF blood concentrations of female employees.

We determined blood concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in 41 female employees with previous exposure to pentachlorophenol-based wood preservatives from 10 day-care centers in the Hamburg, Germany, area. We compared the blood concentrations with estimated age-dependent reference values and analyzed the correlation between PCDD/PCDF indoor air exposure and blood concentrations. The analyses based on the PCDD congeners 1,2,3,4,7,8-, 1,2,3,6,7,8-, and 1,2,3,7,8,9-hexaCDD (hexaCDD), 1,2,3,4,6,7,8-heptaCDD (heptaCDD), octaCDD, and the 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents calculated according to the international NATO-CCMS model (I-TEQ). In comparison to the estimated reference values, the blood concentrations of hexaCDD and I-TEQ spread around the mean estimate. Data for octaCDD scattered in some cases distinctly above the upper confidence limit. Reference values for heptaCDD could not be estimated. The correlation between PCDD/PCDF indoor air exposure and PCDD/PCDF blood concentrations was examined by linear multiple regression analysis considering different exposure variables and taking confounders into account. Analyses were carried out with the total study group and with a restricted subgroup. Associations were shown between the PCDD/PCDF indoor air concentrations and blood concentrations for heptaCDD and for the I-TEQ, whereas hexaCDD showed no association. OctaCDD showed a negative association in the total study group and no association in the subgroup analysis. In summary, the analyses showed no clear association between PCDD/PCDF indoor air exposure in day-care centers and PCDD/PCDF blood levels of female employees previously exposed to wood preservatives. By contrast, the results consistently indicated a positive association between PCDD/PCDF blood concentrations and exposure to wood preservatives in private homes.