Saturated and unsaturated fluorotelomer carboxylic acids have been identified as intermediates in the degradation of fluorotelomer alcohols to perfluorinated carboxylic acids (PFCAs). Although surface waters are the likely environmental sink for telomer acids, no fate or toxicity data exist for this matrix. We assessed the acute toxicity of the 4:2, 6:2, 8:2, and 10:2 saturated (FTCA) and unsaturated (FTUCA) fluorotelomer carboxylic acids to Daphnia magna, Chironomus tentans, and Lemna gibba. In general, toxicity increased with increasing fluorocarbon (FC) chain length, particularly for telomer acids of g8 FCs. In addition, the FTCAs were generally more toxic than the corresponding FTUCAs. Acute EC50s ranged from 0.025 mg/L (0.04 µmol/L) for D. magna (10:2 FTCA, immobility) to 63 mg/L (167 µmol/L) for C. tentans (6:2 FTCA, growth). While chain-length trends observed in the current study agree with those previously reported for PFCAs, the toxicity thresholds generated here are up to 10 000 times smaller. Our data provide the first evidence that PFCA precursors are more toxic than the PFCAs themselves.

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.