Date of Award

1-1-2009

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Environmental Health Sciences

Content Description

1 online resource (xxi, 225 pages) : illustrations (some color), map.

Dissertation/Thesis Chair

Kurunthachalam Kannan

Committee Members

Kenneth M Aldous, Robert L Jansing, Xinxin Ding, Shin Takahashi

Keywords

Biomonitoring, Environmental, Exposure, Lactational, Perfluorochemicals, Placental, Biological monitoring, Surface active agents

Subject Categories

Environmental Health

Abstract

Perfluorochemicals (PFCs) have been used as surfactants and surface protectors in a large number of consumer products. PFCs have been reported to elicit adverse health effects in laboratory animals and humans, and have been detected in foodstuffs and in human bodies. In this dissertation, analytical methods were developed for the determination of trace levels of PFCs in human blood, dried blood spot, breast milk, saliva, and urine. An assessment of human exposure to PFCs was performed by analyzing human specimens collected from the United States and several Asian countries. Blood, breast milk, and dried blood spots were found to be suitable matrices for biomonitoring of PFCs in humans. The partitioning of PFCs among blood, breast milk, saliva, and urine was found to be in the ratio of 1000:10:1:1 for PFOS and 140:10:1:1 for PFOA. Biomonitoring of PFCs in the plasma of World Trade Center responders revealed greater exposure levels in more-smoke and more-dust exposed individuals than less smoke- and dust-exposed individuals. Monitoring of PFCs in archived dried blood spots (1997-2007) from newborn babies revealed decreasing levels of PFOS, PFHxS, and PFOSA after the phase-out of production of PFOS in 2001. The disappearance half -lives of PFOS, PFHxS, and PFOSA were calculated to be 4.6, 9.2, and 1.8 yrs, respectively. The lack of decrease in PFOA and PFNA concentrations in newborn babies suggested continuing exposure to these PFCs. PFCs were found to cross the placental barrier in the ratio of 0.29-0.69 in comparison with mother's blood. Breastfeeding was found to be the primary exposure pathway in infants, contributing to over 70% of the total daily intakes of PFOS and PFOA. The average daily intakes of PFOS and PFOA by infants, through all sources, were estimated to be 18.9 and 10.9 ng/kg bw/day, respectively, which did not exceed the current reference doses (RfDs) recommended by the USEPA's OW. This dissertation reported the levels of PFCs in newborn blood specimens from newborn screening program, breast milk from the United States and seven Asian countries, and in infant formula and dairy milk, for the first time.

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