Chemical dispersant potentiates crude oil impacts on growth, reproduction, and gene expression in Caenorhabditis elegans

Abstract

The economic, environmental, and human health impacts of the deepwater horizon (DWH) oil spill have been of significant concern in the general public and among scientists. This study employs parallel experiments to test the effects of crude oil from the DWH oil well, chemical dispersant Corexit 9500A, and dispersant-oil mixture on growth and reproduction in the model organism Caenorhabditis elegans. Both the crude oil and the dispersant significantly inhibited the reproduction of C. elegans. Dose-dependent inhibitions of hatched larvae production were observed in worms exposed to both crude oil and dispersant. Importantly, the chemical dispersant Corexit 9500A potentiated crude oil effects; dispersant-oil mixture induced more significant effects than oil or dispersant-alone exposures. While oil-alone exposure and dispersant-alone exposure have none to moderate inhibitory effects on hatched larvae production, respectively, the mixture of dispersant and oil induced much more significant inhibition of offspring production. The production of hatched larvae was almost completely inhibited by several high concentrations of the dispersant-oil mixture. This suggests a sensitive bioassay for future investigation of oil/dispersant impacts on organisms. We also investigated the effects of crude oil/dispersant exposure at the molecular level by measuring the expressions of 31 functional genes. Results showed that the dispersant and the dispersant-oil mixture induced aberrant expressions of 12 protein-coding genes (cat-4, trxr-2, sdhb-1, lev-8, lin-39, unc-115, prdx-3, sod-1, acr-16, ric-3, unc-68, and acr-8). These 12 genes are associated with a variety of biological processes, including egg-laying, oxidative stress, muscle contraction, and neurological functions. In summary, the toxicity potentiating effect of chemical dispersant must be taken into consideration in future crude oil cleanup applications.

Stress response of the black coral Leiopathes glaberrima when exposed to sub-lethal amounts of crude oil and dispersant

“…However, studies on Caenorhabditis elegans have also reported aberrant gene expression in response to oil and dispersed oil treatments, with lack of response to exposure to dispersant alone (Zhang et al, 2013). Nevertheless, the eight annotated genes that responded to the dispersant treatments were also detected in other experiments evaluating coral response to stress.…”

Concentrations in human blood of petroleum hydrocarbons associated with the BP/Deepwater Horizon oil spill, Gulf of Mexico

“…Polycyclic aromatic hydrocarbons (PAHs) are highly toxic compounds of light crude and can bio-concentrate in marine organisms (Meador 2003) and humans (Knap et al 2002;Fleming et al 2006). In addition, oil combined with dispersants, as was the case in this spill, are known to be more toxic than either oil or dispersant alone (National Research Council 2005;Zhang et al 2013;Polli et al 2014).…”

Nanoparticle emulsifiers based on bifunctionalized cellulose nanocrystals as marine diesel oil–water emulsion stabilizers

“…Because of bio-based nanoparticles' potential inherent biodegradability, researchers have considered such nanoparticles to be especially beneficial as oil-spill response agents for promoting oil dispersion; many of the currently available soluble synthetic polymeric dispersants, in contrast, have been associated with negative health and environmental impacts [18][19][20]. Certain nanoparticles have been reported to possess low toxicity and reduced negative impact on marine organisms, with good stabilization performance [21].…”