The Biodegradation of Dispersed Oil Does Not Induce Toxicity at Environmentally-Relevant Concentrations

Applying dispersants to spilled crude oil results in an oil in water dispersion of microscopic oil droplets that soon dilutes to levels below 1 ppm oil. These levels are substantially below those known to induce acute toxicity in 96-hour tests. We show here that oil hydrocarbons are biodegraded very rapidly in such situations (50% loss in 4 days in this experiment), and that no increase in acute toxicity to mysids (Americamysis bahia) is seen during this biodegradation, or over the following 20 days as the oil is further degraded (78% loss of detectable hydrocarbons in this experiment).