Day: October 26, 2021

Yesterday, I got reading a bit more about fluorine compounds and grew increasingly concerned when I was reading about perfluorooctanoic acid (PFOA), especially the highlighted sections below:

Perfluorooctanoic acid (PFOA) (conjugate base perfluorooctanoate)—also known as C8—is a perfluorinated carboxylic acid produced and used worldwide as an industrial surfactant in chemical processes and as a material feedstock, and is a health concern and subject to regulatory action and voluntary industrial phase-outs. PFOA is considered a surfactant, or fluorosurfactant, due to its chemical structure consisting of a perfluorinated, n-octyl “tail group” and a carboxylate “head group”. The head group can be described as hydrophilic while the fluorocarbon tail is both hydrophobic and lipophobic; The tail group is inert and does not interact strongly with polar or non-polar chemical moieties; the head group is reactive and interacts strongly with polar groups, specifically water. The “tail” is hydrophobic due to being non-polar and lipophobic because fluorocarbons are less susceptible to the London dispersion force than hydrocarbons.

PFOA is used for several industrial applications, including carpeting, upholstery, apparel, floor wax, textiles, fire fighting foam and sealants. PFOA serves as a surfactant in the emulsion polymerization of fluoropolymers and as a building block for the synthesis of perfluoroalkyl-substituted compounds, polymers, and polymeric materials. PFOA has been manufactured since the 1940s in industrial quantities. It is also formed by the degradation of precursors such as some fluorotelomers. PFOA is used as a surfactant because it can lower the surface tension of water more than hydrocarbon surfactants while having exceptional stability due to having perfluoroalkyl tail group. The stability of PFOA is desired industrially but is a cause of concern environmentally.

A majority of waste water treatment plants (WWTPs) that have been tested output more PFOA than is input, and this increased output has been attributed to the biodegradation of fluorotelomer alcohols. A current PFOA precursor concern are fluorotelomer-based polymers; fluorotelomer alcohols attached to hydrocarbon backbones via ester linkages may detach and be free to biodegrade to PFOA.

PFOA and PFOS were detected in “very high” (low parts per million) levels in agricultural fields for grazing beef cattle and crops around Decatur, AL. The approximately 5000 acres of land were fertilized with “treated municipal sewage sludge, or biosolids”. PFOA was also detected in fodder grass grown in these soils and the blood of the cattle feeding on this grass. The water treatment plant received process wastewater from a nearby perfluorochemical manufacturing plant. 3M says they managed their own wastes, but Daikin America “discharged process wastewater to the municipal waste treatment plant”. If traced to meat, it would be the first time perfluorochemicals were traced from sludge to food. However, the USDA reported—with a detection limits of 20 parts per billion—non-detectable levels for both PFOA and PFOS in cattle muscle tissue.

PFOA is frequently found in household dust, making it an important exposure route for adults, but more substantially, children. Children have higher exposures to PFOA through dust compared to adults. Hand-to-mouth contact and proximity to high concentrations of dust make them more susceptible to ingestion, and increases PFOA exposure. One study showed significant positive associations were recognized between dust ingestion and PFOA serum concentrations. However, an alternate study found exposure due to dust ingestion was associated with minimal risk.

Also this article on fluorotelomer alcohol was quite concerning:

Fluorotelomer alcohols can biodegrade to perfluorinated carboxylic acids, whichpersist in the environment and are found in the blood serum of populations and wildlife, such as the toxic PFOA and PFNA. The fluorotelomer alcohols 6:2 FTOH and 8:2 FTOH have been found to be estrogenic.

The atmospheric oxidation of fluorotelomer alcohols can also result in anthropogenic perfluorinated carboxylic acids. In addition to perfluorinated carboxylic acids, fluorotelomer alcohols can degrade to form unsaturated carboxylic acids which have been detected in bottlenose dolphins.[10] Fluorotelomer alcohols such as 4:2 FTOH, 6:2 FTOH, 8:2 FTOH, and 10:2 FTOH, have been identified as residuals in consumer products such as stain repellents, Zonyl FSE, and windshield wash, among others. The United States Environmental Protection Agency has asked eight chemical companies to reduce the amount of residuals, including fluorotelomer alcohols, from products.