Quantal response of Paleomonetes africanus in locally formulated drilling mud lubricants

• Published in: Toxicological and environmental chemistry Vol. 88; no. 4; pp. 719 - 727
• Main Authors: Otaigbe, John O. E., Osuji, Leo C., Azubike, Adolphus N.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.10.2006
• Subjects: Drilling mud; lubricants; Paleomonetes africanus; quantal response; toxicity
• ISSN: 0277-2248; 1029-0486
• DOI: 10.1080/02772240600903029

The toxic potency of three locally formulated drilling mud lubricants against Paleomonetes africanus, a brackish water crustacean commonly found in the oil producing Niger Delta (Nigeria), was evaluated. A 96 h exposure to quantal (lethal) doses of the mud lubricants gave LC 50 (median lethal concentration) of 350, 620 and 210 mg L −1 , respectively. The mud lubricant with the highest molecular weight of 40,000 g mol −1 (lubricant 2) had the least toxicity on the organisms, attributable to the reduced rate of diffusion into the vital cells of the test organism. The higher toxicity of lubricant 3 over lubricant 1, despite its higher molecular weight, might be as a result of its higher acid value of 21.60 mg KOH g −1 . The results show that the test lubricants would be environmentally friendly within the baseline concentrations and lethal times (LT 50 ) measured.