Toxicity assessment of drilling additives

The Petroleum Services Association of Canada (PSAC) has collected product toxicity data from drilling fluid companies, and compiled a list of drilling products which were found to yield potential toxic results. The list includes bactericides, corrosion inhibitors, defoamers, emulsifier/de-emulsifiers, foaming agents, lubricants, polymer stabilizers, shale control inhibitors and surfactants. Drilling mud toxicity is determined through the use of bioassays, primarily the MicrotoxTM bioluminescence test. Biological tests allow for the detection of possible toxic components in drilling waste, which might not be detected through chemical analysis. This study determined whether the bacterial luminescence test provides adequate toxicity data for assurance of ecological protection. Currently, the test uses one organism from one trophic level. It was argued that a single bioassay that represents a single trophic level may not give a true indication of the product toxicity to the whole ecosystem because different species have different sensitivities to different compounds and conditions. It was suggested that use of a test battery would give a better perspective of biological effects. Results of this study showed that in general, the bacterial luminescence test provides adequate toxicity data, but its limitations should be borne in mind in interpreting results. 10 refs., 4 tabs