Dispersants have greatest toxicity to fish in coastal waters where salinities are low. - GreenMedInfo Summary
Influence of salinity and fish species on PAH uptake from dispersed crude oil.
Mar Pollut Bull. 2006 Oct;52(10):1182-9. Epub 2006 Mar 6. PMID: 16678214
School of Environmental Studies, Queens University, Kingston, ON, Canada K7L 3N6.
The use of chemical oil dispersants to minimize spill impacts causes a transient increase in hydrocarbon concentrations in water, which increases the risk to aquatic species if toxic components become more bioavailable. The risk of effects depends on the extent to which dispersants enhance the exposure to toxic components, such as polycyclic aromatic hydrocarbons (PAH). Increased salinities can reduce the solubility of PAH and the efficiency of oil dispersants. This study measured changes in the induction of CYP1A enzymes of fish to demonstrate the effect of salinity on PAH availability. Freshwater rainbow trout and euryhaline mummichog were exposed to water accommodated fractions (WAF), and chemically-enhanced water accommodated fractions (CEWAF) at 0 per thousand, 15 per thousand, and 30 per thousand salinity. For both species, PAH exposure decreased as salinity increased whereas dispersant effectiveness decreased only at the highest salinity. Hence, risks to fish of PAH from dispersed oil will be greatest in coastal waters where salinities are low.