Date of Award

2021

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Specialization

Chemical Oceanography

Department

Oceanography

First Advisor

Rainer Lohmann

Abstract

Neutral, volatile perfluorinated alkyl substance (PFAS) precursors, such as fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamides (FOSAs), and perfluorooctane sulfonamide ethanol (FOSEs) are industrial (by)products that are commonly present in indoor environments, and have been found in urban, industrial, and even rural locations. They have also been detected in remote regions, such as the Arctic, suggesting that these compounds are transported long distances in the. However, measuring volatile and neutral PFAS in air and water has proven to be challenging. Therefore, in order to accurately measure these compounds in different indoor and outdoor environments from urban, rural, industrial and remote regions, we proposed the use of apolar polyethylene (PE) sheets as a passive detection tool for air and water.

The compounds of interest in this study included 6:2 FTOH, 8:2 FTOH, 10:2 FTOH. 8:2 FTAcr, 10:2 FTAcr, MeFOSA, MeFOSE, EtFOSA, and EtFOSE. Indoor sampling locations included classrooms, offices and laboratories from the University of Rhode Island, kindergarten classrooms and an outdoor clothing store in northern California, and classrooms, offices, laboratories and homes from the central valley of Jalisco, Mexico. Outdoor sampling of air and water included the North American Great Lakes, the Canadian Arctic, and Dhaka, Bangladesh. Studies were evaluated using two types of pre-cleaned PE passive samplers differentiated by thickness, and samples were analyzed by gas chromatography-mass spectrometry. These PE sheets were used to determine the partitioning coefficients (KPEa) and uptake of the volatile PFAS by these samplers. Results from the kinetic study showed that after 14 days of exposure equilibrium of the compounds into the PE sheets had been reached. Passive samplers were then paired with Radiello active samplers at an outdoor gear and clothing store to determine the KPEa of each compound. Partitioning between both PE sheets suggests that interactions of the passive samplers with the volatile PFAS are occurring by absorption. Gas-phase concentrations were paired with concurrently analyzed dust samples taken at the same locations in Californian kindergartens, and indoor air concentrations were linked to carpet and dust concentrations and the ventilation rates of the indoor environments.

Results from all indoor studies indicated that volatile and neutral PFAS are ubiquitous in these environments, but that composition and concentration will vary depending on the contents of each location such as furniture, carpet, clothing, as well as ventilation rates. Volatile 6:2 FTOH was dominant in the U.S. indoor locations which was likely a reflection of the banning of longer chained PFAS and their precursors in North America. On the other hand, 10:2 FTOH was most abundant in the Mexican sites which pointed to the presence of older fluorinated products. Volatile PFAS from air, carpet and dust were closely related to each other which indicates that carpets and dust are major sources of FTOHs in air. Nonetheless, air poses the largest exposure risk of FTOH in children age 2 to 6 years old.

Outdoor air and water from the textile manufacturing industry in Dhaka, Bangladesh had FTOH concentrations comparable to those found indoors. The latter is significant because indoor air concentrations tend to be half as high as outdoor air concentrations. Thus, health concerns should be raised given the elevated concentrations found in ambient air and water. Concentration of FTOHs in the air from North American Great Lakes was higher than the Canadian Arctic. This suggested that the amount of volatile and neutral PFAS present in air and water was in direct relationship with the size of its human settlements, and PFAS are ubiquitous and are capable of being transported atmospherically to remote regions.

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