A Technical Report on Rapid Assessment of Pesticide Contaminated Sites in Kenya: Case Studies of Menengai Crater, Kitengela Pesticide Store and Wajir Lmd Site

Abstract

Evaluating the risk posed by a contaminated site involves assessing hazards, receptors and exposure pathways. Since risk exists only when all three of these components are present, it is advantageous to use a multiplicative model as the REA rather than a summative model for assessing risk potential. Hazard (contaminant), receptor and exposure pathway scores are developed under a methodological framework that reduces opportunities for judgmental bias. The model was therefore used to categorize and prioritize the visited sites and recommend the sites which require immediate detailed action. The purpose of the site assessments was to identify the existence, source, nature, and extent of POPs contamination of Menengai Crater, Kitengela and Wajir dump sites. From the residual chemical analysis of samples collected, the sites are heavily contaminated with residual POPs (lindane, aldrin, dieldrin, 2,4- DDE, 2,4-DDT, and endrin) and other residual pyrethroids (bifenthrin, cypermethrin, pendimethalin, and permethrin) beyond the set International Standards for such residual pollutants in the environment (USAEPA, Dutch Intervention POPs Levels)(< 0.05 mg/Kg). Menengai Crater 1, Kitengela and Wajir LMD indicated quite high levels of the POPs. The levels of POPs recorded in the analysis are indicative of potential contamination of humans and animals and thus posing a great environmental threat. The pollutants are able to pollute surface and ground water sources, contaminate surface soil both on site and away through long range dust transportation. The analysis of REA questionnaire indicated that Wajir LMD site was the most at risk followed by Menengai Crater Dump Site 1, and Kitengela respectively. Wajir LMD was the most at risk site due to the proximity and easy access to the site by human beings and thus poses a great health threat to the local community members living and accessing the site. There was strong evidence of both horizontal and vertical POPs contamination in all sites. The proximity of receptors such as homesteads and drinking water sources (at Wajir LMD and Kitengela) to the contaminated sites, strongly indicate that the sites are potential human hazard and detailed investigations should be put in place to ascertain the extent of contamination. The study proved with great certainty that the visited sites are heavily contaminated with POPs and measures to reclaim and remediate the sites to avoid future human health and environment catastrophe should be put in place.