The effects of Tri‐ and dichloroacetic acids on the oxygen consumption of the dragonfly nymph Aeschna Umbrosa

Abstract

The discovery of trihalomethanes in drinking water and the subsequent establishment of limits by the U.S. EPA aroused concern over the potential toxicological effects of related by‐products of water chlorination. Two recently characterized haloforms, trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA), have been reported to occur in drinking water at levels comparable to the trihalomethanes.¹ As a consequence, this research examined the effects of these two chemicals on the oxygen consumption rate of the dragonfly nymph Aeschna umbrosa.

Nymphs were exposed for 8 hours to one of three haloform preparations—TCAA, DCAA or combined—in a gravity feed flow‐through testing apparatus. Four treatment levels (1, 10, 100 and 1000 μg/l) and an unexposed control were tested.

Results indicated a significant elevation in oxygen consumption of nymphs exposed to 100 and 1000 μg/l of all three haloform preparations (p < 0.001) but not at lower concentrations.

Key words:

• chlorination
• trichloroacetic acid
• dichloroacetic acid
• chlorine
• respiration
• dragonfly
• aquatic toxicology