Chronic toxicity of fluorotelomer acids to Daphnia magna and Chironomus dilutus

Abstract

Saturated and unsaturated fluorotelomer carboxylic acids (fluorotelomer acids: FTAs) represent important intermediates in the degradation of fluorotelomer alcohols to perfluorinated carboxylic acids (PFCAs). Recent studies have detected FTAs at low concentrations (ng/L) in precipitation and surface waters; however, information regarding chronic toxicity is lacking. The present study assessed the chronic toxicity of the 8:2 saturated fluorotelomer carboxylic acid (8:2 FTCA) to Chironomus dilutus and the 10:2 saturated and unsaturated fluorotelomer carboxylic acids (10:2 FTCA and 10:2 fluorotelomer unsaturated carboxylic acid [FTuCA]) to Daphnia magna in separate life-cycle tests. In D. magna tests the FTCA was consistently more toxic than the FTuCA. Lethal concentrations (LC50s) were 150 and>60 microg/L for FTuCA and FTCA, respectively. Reproduction was significantly reduced relative to the controls, with respective median effective concentrations (EC50s) for time to first brood and mean number of offspring/female of 287 and 214 microg/L for FTuCA and 50 and 48 microg/L for FTCA. In tests with C. dilutus, EC50s for survival and growth at 20 d were 2,610 and 1,250 microg/L. Total emergence and time to first emergence, the most sensitive endpoints, yielded EC50s of 440 and 890 microg/L. Few adults emerged and no reproduction occurred at the two highest concentrations (600 and 1540 microg/L). Mean number of eggs/female was not affected. These results represent the first chronic toxicity data for FTCAs and additional evidence that FTCAs are more toxic than some PFCAs. While the results indicate that current environmental concentrations of FTAs likely pose negligible risk to aquatic biota, additional quantification of FTAs in surface waters and assessment of their toxicity is needed before meaningful assessments of potential risks to aquatic biota are possible.

Toxicokinetics of 8:2 fluorotelomer alcohol (8:2-FTOH) in male and female Hsd:Sprague Dawley SD rats after intravenous and gavage administration

“…Findings from other studies also show this trend, where females generally had higher concentrations of upstream metabolites (8:2-FTOH, 8:2-fluorotelomer acid, 7:3-FTA, and unsaturated 7:3-FTA) while males had more downstream metabolites (PFOA, perfluorononanoic acid, perfluoroheptanoic acid) [15,36]. Since some studies have found precursor FTAs to be more toxic than PFCAs [[50], [51], [52]], higher concentrations of FTAs in female rodents may be of concern. These different metabolite profiles in males and females are likely primarily due to the major sex difference in the half-life of PFOA.…”

Fate and effects of poly‐ and perfluoroalkyl substances in the aquatic environment: A review

“…The PFAS precursors (e.g., FTOH, FASAs, FASEs, PAPs) are subject to a variety transformation pathways in the atmosphere or under aerobic and anaerobic conditions in other environmental compartments . Moreover, intermediate degradation products (i.e., FTUALs, FTALs, FTUCAs, FTCAs) formed during both atmospheric transformation and biotransformation are very reactive and have shown acute and chronic toxicity to aquatic invertebrates and green algae . The transport processes of these final degradation products proceed mainly in the water phase but can also occur via seaspray or gas‐phase and particle‐bound transport in the atmosphere .…”

Biotransformation of 8:2 fluorotelomer alcohol by recombinant human cytochrome P450s, human liver microsomes and human liver cytosol

“…8:2 FTOH and 6:2 FTOH (x ¼ 5) were suggested to induce estrogenic effects in animal models. [19][20][21][22][23] The intermediate metabolites, specically 8:2 FTAL, 8:2 FTUAL, 8:2 FTCA and 8:2 FTUCA, showed higher toxicity than PFAAs in both aquatic organisms 24,25 and human liver epithelial (THLE-2) cells following the order of FTUALs $ FTALs > FTUCAs $ FTCAs > PFAAs. 26 Martin et al found that electrophilic aldehydes and acids were responsible for the depletion of glutathione (GSH) and increased protein carbonylation and lipid peroxidation in isolated rat hepatocytes aer dosing 8:2 FTOH.…”