PARENT SESSION
SA9 - Fluorinated Chemicals in the Environment
Chair: Mabury, Scott¹, ¹ 80 St. George Street, Toronto, ON, CANADA
Co-chair: Solomon, Keith ², ² Bovey Building, Gordon Street, Guelph, ON, CANADA
8:00 AM to 12:00 PM - Sunday, 17 November 2002
Room Ballroom E

(090) Acute and Chronic Toxicity of Fluorinated Surfactants to the midge Chironomus tentans.

Sibley, Paul^*,1, Warne, Amanda¹, MacDonald, Michelle, Stock, Naomi², Mabury, Scott², Solomon, Keith¹, ¹ University of Guelph, Guelph, Ontario, Canada² University of Toronto, Toronto, Ontario, Canada

ABSTRACT- Interest in the environmental fate and effects of fluorinated surfactants has increased significantly in recent years due to the extremely high persistence and unique chemical properties of these compounds. The objective of this study was to assess the acute and chronic toxicity of perfluorooctanoic acid (PFOS) and perfluoroctanoic acid (PFOA) toward the midge Chironomus tentans under field and laboratory conditions. In an initial study of PFOS in outdoor aquatic ecosystems, no C. tentans survived at any concentration (>300 /L) in in situ exposures compared to 67% survival in the controls. Subsequent 10-d acute laboratory assessments were conducted with both PFOS and PFOA at a concentration range from 0.1-100,000 /L. PFOA exhibited no toxicity at any concentration. In contrast, PFOS was highly toxic, with an LC50 of 45 /L and an EC50 (growth) of 42 /L. Behavioural signs of stress were observed at concentrations as low as 10 /L. A second test with PFOS (concentrations: 1-140 ug/L) yielded similar results for growth (EC50 = 65 /L) but not survival (LC50 >140 /L). These data indicate that C. tentans is substantially more sensitive to PFOS than has been observed in other invertebrates. To better define the scope of this sensitivity, we recently initiated a life cycle test (60 d) with C. tentans using PFOS at a concentration range of 1-100 /L to monitor survival, growth, emergence and reproductive output. Preliminary results indicate a significant reduction in growth at the two highest concentrations (50/100 /L). The increased sensitivity of C. tentans may reflect an interaction between PFOS and haemoglobin. For example, in the field study, small "white" midges (no haemoglobin) were unaffected by PFOS and occurred in all exposure chambers. To further test this hypothesis, additional tests will be conducted with the closely related species C. riparius.

Key words: Perfluorinated surfactants, Acute and chronic toxicity, Chironomus tentans