African Journal of Biotechnology Vol. 5 (11), pp. 1113-1117, 2 June 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Toxicity of Neatex (industrial detergent) and Norust CR 486 (corrosion inhibitors) to earthworms (Aporrectodea longa) in naturally spiked soil

EZEMONYE L. I. N.¹*, OGELEKA D. F.² and OKEIMEN F. E.²

¹Department of Animal and Environmental Biology, University of Benin, Benin City, Nigeria.

²Department of Chemistry, University of Benin, Benin City, Nigeria.

*Corresponding author. E-mail: ezemslaw@yahoo.com, dorysafam@yahoo.com. Tel: +234 80 23353847, 80 23243514, 80 23324405.

Accepted 9 May, 2006

Ecological effects of indiscriminate disposal of industrial chemicals into soils of the Niger Delta environment of Nigeria were assessed using earthworms in spiked natural soil in the laboratory. Populations of indigenous epigeic adult earthworms, Aporrectodea longa, were exposed to varying concentrations of two chemicals (industrial detergent and corrosion inhibitor) in natural soil to determine the acute toxicity of the chemicals. Earthworm acute toxicity test (OECD) 207 method was employed. After two weeks of earthworm exposure to Neatex and Norust CR 486 concentrations of 62.5, 125, 250 and 500 mg/kg, percentage mortality was measured as the ecological endpoint in the earthworms. Based on OECD 2003 guidelines, the chemically spiked soil rating showed that both chemicals were slightly toxic. The estimated LC50 concentrations showed that Norust CR 486 (corrosion inhibitor) was more toxic than Neatex (detergent) at p < 0.05, t = 8.213. Earthworm mean mortality in both chemicals increased with increasing concentrations and exposure duration. Mean mortality observed in Neatex and Norust CR 486 were significantly different from the negative control suggesting that mortality may be attributed to the effect of the chemicals. The results obtained are therefore indications of early warning signs of future soil deteriorations occasioned by indiscriminate disposal of these chemicals in the Niger Delta environment. This calls for regular monitoring and sustainable effluent disposal management.

Key words: Earthworms, chemicals, mortality, and ecotoxicology.