Acute Aquatic Toxicity and Dispersing Effectiveness of Oil Spill Dispersants: Results of a Canadian Oil Dispersant Testing Program (1973 to 1977)

Publisher Website
Google Scholar
Abstract
An oil spill dispersant testing program was initiated in 1973 to evaluate the toxicity and dispersing effectiveness of dispersants submitted to Fisheries and Environment Canada for approval prior to use in Canadian waters.Screening toxicity tests with rainbow trout (Salmo gairdneri) were performed initially on 19 dispersants. Thirteen were considered sufficiently nonacutely toxic to justify further evaluation using methods and criteria of the Canadian Guidelines on the use and acceptability of oil spill dispersants.Twelve of the 13 dispersants had 4-day LC50's to rainbow trout ranging from 50 to 39 360 mg/litre, while the 4-day LC50's for 12 dispersant/No. 2B fuel oil (1:1) mixtures ranged from 35 to 300 mg/litre. Six dispersants passed the toxicity criteria with 4-day LC50's greater than 1000 mg/litre for the dispersant and 100 mg/litre for the dispersant-oil mixture.Effectiveness tests were conducted with No. 2B fuel, Lago Medio crude oil, and medium and heavy Bunker oils. Twelve dispersants passed the effectiveness criterion by dispersing greater than 65 percent of one or more types of oil. Effectiveness of dispersants varied with oil type and with temperature and salinity of the water.The dispersants BP1100X, Corexit 8666, Drew Chemical OSE 71, Drew Chemical OSE 72, Oilsperse 43, and Sugee #2 passed both the toxicity and effectiveness criteria and were placed on the Canadian standard list of acceptable oil spill dispersants.Acute lethal toxicity tests with BP1100X and Sugee #2 showed that rainbow trout in fresh water were more sensitive than two marine fish, Fundulus heteroclitus and Menidia menidia, while fourth-stage larval lobsters, Homarus americanus, were the least sensitive.