Bull. Environ. Contam. Toxicol. (1995) 54:461)--465 9 1995 Springer-Verlag New York Inc. iSnviron rrmntal Contamination and Toxicology Organochlorine Pesticide Residues in Cereals in Nigerian Markets O. Osibanjo, 1 A. Adeyeye2 1Depa~ment of Chemistry, University of Ibadan, Ibadan, Nigeria 2Depa~ment of Science Laboratory Technology, The Polytechnic, Iree, Osun State, Nigeria Received: 20 June 1993/Accepted: 25 August 1994 Cereal grains, including maize, rice, sorghum and millet cons- titute a major class of staple food in Nigeria, consumed through- out the whole country. Their dietary importance compares only with the tuber crops. As such, their production is now being intensified nationwide to make for short-falls between demand and supply for consumption and use in poultry and other agro- based industries. For decades cereal production and storage have been accompanied by the use of pesticides (North 1978). Because of pesticides' toxic nature and persistence in the environment, surveys and continuous monitoring programmes of pesticide residues in foods have been carried out for over two decades in many deve- loped countries such as the United States of America (USA), (Duggan et al 1983; Luke et al 1988), Britain (Egan and Weston 1977), Canada (Environment Canada 1988), etc. In Nigeria, limited data are available on pesticide residues in fish (Osibanjo and Bamgbose 1990), but data on pesticide residues in cereals and other foodstuffs are lacking. The aim of this work is to report the residue levels of organochlorine pes- ticides (OCPs) in cereals in Nigeria, so as to generate base- line data upon which future monitoring programmes could be accumulated. MATERIALS AND METHODS Samples were purchased from open markets twice in 12 major towns all over the country, (Fig. i) between December, 1989 and May, 1990. All samples were locally produced. Each sample was ground into powder, stored in a glass bottle and kept in a freezer prior to analysis. All solvents were redistilled from analytical grade supplies and sodium sulphate was Soxhlet extracted before use. Each (20g) sample was Soxhlet extracted with hexane using the method of Thompson et al (1970). A micro-column (7mm i.d.) was packed with ig of 5% deactivated silica gel (previously activated overnight at 300~ and 0.Sg anhydrous sodium sulphate added on top for sample clean-up, Correspondence to: A. Adeyeye 460