Pesticides in Kenya 49Chapter 4 Pesticides in Kenya S.O. Wandiga, J.O. Lalah, and P.N. Kaigwara INTRODUCTION The republic of Kenya lies on the eastern side of the African continent, between Lat. 4 o 40'N and 4 o 40'S and between Long. 33°50'W and 41°45'E (NEAP, 1994). The equator bisects the country in almost two equal parts. The climate of Kenya is controlled by movement of the intertropical convergence zone (ITCZ), whose influence is then modified by the altitudinal differences that give rise to Kenya’s varied climatic regimes (NEAP, 1994). The country’s equatorial location and its position adjacent to the Indian Ocean also influence the local climate. Kenyan soils are grouped into various units (NEAP, 1994) based largely on their physical and chemical properties. These play a major role in explaining vegetation types and their distribution patterns. Kenya may be divided into four major agroecological zones (AEZ) namely the highlands, savannah, coastal, and arid and semi-arid lands (ASAL) (Figure 4.1). The zones have distinct humidity ranges, mean annual temperatures, rainfall patterns, and altitudes that largely dictate their respective ecological potentials. Kenya’s population was estimated at 27.5 million in 1995 and was growing at a rate of 2.9 percent per annum (NDP, 1997). Its economy is predominantly agriculture and agroforestry-based, contributing 26 percent to the gross domestic product (GDP) in 1997 (NDP, 1997). Agricultural activities are concentrated in the highlands (high potential), savannah, and coastal (medium potential) AEZs (NEAP, 1994). PESTICIDE REGULATION IN KENYA History of pesticide usage Control of the general use and handling of pesticides in Kenya goes back to the colonial era. The earliest recorded legislation dates from 6 September 1921 when the Public Health Act, Cap 242, was passed by the colonial government. Sixteen years later, a second Act of Parliament dealing with Cattle Cleansing, Cap 358, was passed on 27 April 1937. This Act prescribed various preparations for destroying © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts 50 S.O. Wandiga, J.O. Lalah and P.N. Kaigwara ticks. These preparations are still retained in law though several amendments have modified the original prescriptions. At the height of Kenya’s struggle for independence, when the colonial govern- ment declared emergency rules, it also adopted a Voluntary Precaution Scheme for the agricultural industry. Compliance with the scheme was on a voluntary basis. This Scheme led to the proclamation of the Poisonous Substances Ordinance of 1954. The ordinance was based on the United Kingdom Act of 1952, which provided for the protection of employees against risk of poisoning by certain substances used in agriculture and incidental and connected matters. On the eve of Kenyan independence, the Pharmacy and Poisons Act of Parliament was passed by Westminster on 1 May 1957. The aim of this Act was to incorporate provisions in the law to provide for the control of the profession of pharmacy and the trade in drugs and poisons. Included in this Act was the control of veterinary drugs and poisons with additional rules on the selling and labeling of poisons, including pesticides. The now independent Kenya Parliament passed an Act on 11 May 1965 for the prevention of adulteration of food, drugs, chemical substances, and incidental and connected matters. In this, the Food, Drug and Chemical Substances Act, Figure 4.1 The agroecological zones of Kenya © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts Pesticides in Kenya 51 Cap 254, pesticides were given particular attention, and the term ‘chemical substances’ was defined to refer to any substance or mixture of substances prepared, sold, or represented for use as: • a germicide, • a disinfectant, • an insecticide, • a rodenticide, • an antiseptic, • a pesticide, • a vermicide, • a detergent. For the first time, it also set tolerance levels (in ppm) for pesticides in foodstuffs. This law has neither been amended since then nor has its implementation been effective. The protection of workers in the workplace has not been left outside the ambit of legal protection. The Factories Act, Cap 514, regulates factory working conditions with an aim of maximizing health protection for workers. Other legislative laws passed by Parliament that have a bearing on pesticide use, distribution, and control include the Agriculture Act, Cap 318; the Fertilizers and Animal Foodstuffs Act, Cap 345; the Forest Act, Cap 385; the Plant Protection Act, Cap 324; and the Water Act, Cap 389. Although in some of these Acts pesticides are not specifically mentioned, it is clear that to fulfill the Act’s objectives the control of pesticides may be invoked. The practice in Kenya has been for Parliament to pass sectorial laws for the regulation and control of environmental matters. There is no umbrella law covering all aspects of environmental matters. Such a bill is on the drawing board and it is hoped that when passed by Parliament it will go a long way toward regulating environmental issues, including pesticides. The major deficiency in the present patchwork of laws is their scattered aims and ineffective implementation. Penalties prescribed for offenders have also been overtaken by economic realities. Kenya, therefore, needs an environmental act that will assist it to better manage its environment. Recent attempts to better regulate the use of pesticides are described in the next section. Current pesticide regulations Except for the Poisonous Substances Ordinance, 1954, the rest of the Acts mentioned in the previous section are still in force. A replacement ordinance, called the use of Poisonous Substances Ordinance, which will regulate the protection of people against the risks from exposure to poisonous substances, has been drafted but has not yet been presented to Parliament. The most comprehensive law regulating pesticides is the Pest Control Products Act, which came into law on 19 May 1983. It was established to regulate the © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts 52 S.O. Wandiga, J.O. Lalah and P.N. Kaigwara importation, exportation, manufacture, and distribution of products used for the control of pests, and of the organic function of pesticides on plants and animals. Pest Control Product was defined as ‘a device, product, organism, substance, or a thing that is manufactured for directly or indirectly controlling, preventing, destroying, attracting, or repelling any pest’. The Act established a Pest Control Products Board (PCPB), which became operational in October 1984. PCPB’s mandate as contained in the Act is described below under the respective categories: Regulatory 1 To register and approve for use all pest control products. 2 To regulate the sale and distribution of pest control products through licensing of imports and exports. 3 To inspect and license all facilities used for the manufacture, storage, and distribution of pesticides. 4 To analyze any pesticides for efficiency before recommending for use. Technical 1 To receive and evaluate data from manufacturers and importers on the merits of pest control products. 2 To undertake, as appropriate, short and long term research to evaluate the impact of pesticides on the environment. 3 To collect information from international organizations such as FAO, WHO, EPA, UNEP, etc. that are relevant to pesticide use and regulation. Training and information 1 To educate and inform users and the general public on matters concerning the safety and danger of using pesticides. Other functions that fall under the Training and Information category are advising relevant authorities on aspects of pesticide management, training government extension agents and other interested personnel on pesticide management, and advising the government on the status of approved pesticides. Since its inception in 1986, the Board has also banned or restricted the use of a number of pesticides (Table 4.1). PESTICIDE USE AND DISTRIBUTION Past and current usage patterns Agriculture has been the mainstay of Kenya’s economy. This dependence on agricultural production has led to widespread pesticide use during the last four decades. Lindane was introduced in Kenya in 1949, toxaphene in 1950, DDT in 1956, and dieldrin in 1961 (Kaine, 1976). Other compounds in use during the © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts Pesticides in Kenya 53 1950s included dinitrocresol (DNC) and the OP compounds, TEPP (tetraethyl pyrophosphate) and schradan (Keating, 1983). The livestock industry has been adversely affected by diseases such as East Coast fever or theileriasis (an acute disease of cattle transmitted by ticks and caused by Theileria parva Theiler) and anaplasmosis (a peracute to chronic infectious disease of ruminants frequently caused by blood-feeding insects such as ticks). Acaricides such as chlorfenvinphos have been used to combat the disease vectors. DDT has been instrumental in reducing the incidence of malaria, with the consequence of many lives saved, by controlling malaria’s vector, the Anopheles mosquito. Foxall (1983) reported that K Sh400 million worth of pesticides was being used annually in Kenya. These consisted of 50 percent fungicides, 20 percent insecticides, 20 percent herbicides, and 10 percent acaricides, rodenticides, molluscides, and nematicides, combined. Currently about K Sh2.5 billion worth of pesticides is used in Kenya annually (Mwaisaka, 1999). In 1987, PCPB reported an increase in imports between 1984 and 1986 from K Sh350 million (1984) to K Sh410 million (1985) and then to K Sh580.2 million (1986). Between 1985 and 1987, pesticides worth K Sh1,732.3 million were imported (Mwanthi and Kimani, 1993), while for the period 1987 through 1990 a total of 31,234 T (PCPB, 1994) was imported into the country. The bulk of imported pesticides was consumed locally with less than 3 percent exported to neighboring countries. About 20 percent were imported Table 4.1 Pesticides banned or in restricted use in Kenya (from the Pest Control Products Board) Banned pesticides in Kenya Common name Former use of the pesticide Dibromochloropropane (DBCP) Soil fumigant Ethylene dibromide (EDB) Soil fumigant 2,4,5-T phenoxy herbicide Herbicide Chlordimeform Acaricide/insecticide All isomers of HCH Insecticide Chlordane Insecticide Captafol Fungicide Heptachlor Insecticide Toxaphene (camphechlor) Acaricide Endrin Insecticide Parathion(methyl and ethyl) Insecticides Restricted pesticides in Kenya Common name Permitted use Lindane Seed dressing only Aldrin; dieldrin Termites in building industry – no longer available in Kenya DDT Public health only for control of mosquitoes in mosquito breeding grounds – no longer available in Kenya © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts 54 S.O. Wandiga, J.O. Lalah and P.N. Kaigwara in technical grade form and were formulated locally while the rest were imported as ready to use formulated products. For example, malathion (technical) is used locally for the formulation of 2 percent malathion dust and technical carbofuran (furadan) is used for the preparation of 3G, 5G, and 10G granular formulations. Examples of formulated products imported ready for use include furadan 350 ST and marshal 250 FC (carbosulfan). Tables 4.2 to 4.5 show 1986 through 1995 pesticide imports into Kenya in monetary, metric, and percentage terms. By 1997, the Pest Control Products Board (PCPB) had registered 370 formulations, represent- ing 217 active ingredients for use in Kenya. About 22 percent of the volume imported were highly hazardous, 20 percent moderately hazardous, 45 percent slightly hazardous, and the remainder were unclassified (Ohayo-Mitoko, 1997). A decline in the volume of imports is noticeable between 1988 and 1990. This was probably due to the ban and restriction of some OC pesticides. Munga (1985) reported that 70 T of DDT had been used annually for agricultural pest control on maize and cotton while other OCs, e.g. lindane, aldrin, and dieldrin, were used for seed dressings. DDT was last imported into Kenya in 1985, aldrin and dieldrin in 1992 (PCPB). OCs still in use in Kenya include endosulfan and lindane. Approximately 33 percent of Kenyan farmers, primarily large farm operators, use pesticides. On most small farms, which are mostly subsistence-level farms, there is minimal use of pesticides. Cash crops, such as coffee, use about 50 percent of imported pesticides while horticultural crops require another ~25 percent (Kanja, 1988). Other important crops that require a significant quantity of pesticides are cotton, sugarcane, maize, and tea. Herbicides, as a substitute for mechanical or hand weeding, are also used by coffee, maize, barley, wheat, sugarcane, and tea farmers. The pesticide industry in Kenya The Kenyan pesticide industry comprises companies that manufacture a.i.(s) used in pesticide formulation, formulators contracted to manufacturers of a.i.(s) used Table 4.2 Importation of different groups of pesticides into Kenya (1986–95) (value of cost and freight in M Kshs, adapted from the Pest Control Products Board) Year Insecticides and acaricides Herbicides Others Fungicides Total 1995 707.0 312.1 74.4 682.6 776.4 1994 479.3 286.5 84.5 432.8 1,283.1 1993 428.7 272.2 64.1 441.8 1,206.8 1992 505.0 228.5 101.7 457.1 1,292.3 1991 202.2 146.8 41.8 223.8 614.6 1990 260.3 159.4 55.6 169.2 644.5 1989 208.1 154.2 30.7 328.8 721.8 1988 158.9 145.2 28.5 329.9 662.5 1987 182.3 173.4 28.1 357.3 741.1 1986 134.9 121.3 42.6 281.3 580.1 © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts Pesticides in Kenya 55 Table 4.3 Importation of different groups of pesticides into Kenya (1986–95) (adapted from Pest Control Products Board and quantity expressed in T finished product) Year Insecticides and Acaricides Herbicides Others Fungicides Total 1995 1,413.3 870.6 2,323.0 501.9 5,108.8 1994 1,049.9 747.4 1,671.8 563.3 4,032.4 1993 839 882 1,503 309 3,533 1992 1,670 1,122 2,634 1,164 6,590 1991 1,072 844 1,568 570 4,054 1990 1,572 1,134 1,330 857 4,893 1989 1,571 1,148 4,327 665 7,711 1988 1,089 2,108 4,259 801 8,257 1987 1,206 1,311 715 697 10,371 1986 1,076 112 654 808 9,597 Table 4.4 Importation of different groups of pesticides into Kenya (1986–95) (expressed as a percentage of the total monetary value of imports) Year Insecticides and acaricides Herbicides Fungicides Other Total 1995 39.8 17.6 38.4 4.2 100 1994 37.4 22.3 33.7 6.6 100 1993 35.5 22.6 36.6 5.3 100 1992 39.0 17.7 35.4 7.9 100 1991 32.9 23.9 36.4 6.8 100 1990 40.4 24.7 26.3 6.6 100 1989 28.8 21.4 45.5 8.6 100 1988 24.0 21.9 49.8 4.3 100 1987 24.6 23.4 48.2 4.3 100 1986 23.2 20.9 48.6 7.3 100 Table 4.5 Importation of some pesticides into Kenya (1986–92) Year Malathion Carbofuran Furadan Carbosulfan (technical) (T) (technical) (T) (technical) (L) (technical) (L) 1992 10.0 23.0 15,000 20,000 1991 13.0 10.0 21,000 – a 1990 18.5 12.0 16,000 – 1989 16.0 7.0 10,000 20,000 1988 9.0 14.0 – – 1987 15.0 30.0 2,000 – 1986 20.0 8.0 – – Note: a En dash (–) indicates the product was not imported. © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts 56 S.O. Wandiga, J.O. Lalah and P.N. Kaigwara in the formulation of agricultural chemicals and related products, and contracted representatives of manufacturers of agricultural chemicals and related products not otherwise represented in Kenya. Most firms are overseas-based companies, except for the Pyrethrum Board of Kenya (PBK), which extracts pyrethrins from the pyrethrum plant Chrysanthemum cinerariaefolium Trev. (Compositae). Kenya has been the world’s largest producer of pyrethrum products, exporting ground flowers for the mosquito coil market in addition to refined extract for inclusion in aerosols. To increase toxicity and consequently lower production costs of pyrethrum- containing insecticides, it is combined with synergists, such as piperonyl butoxide, which in themselves are not toxic (Casida, 1973; Vickery and Vickery, 1979). Other companies and organizations are also involved in the distribution and use of pesticides and related products. They include locally formed companies and cooperative societies like the Kenya Farmers Association (KFA). Some manu- facturers do not have facilities in Kenya but market their pesticides through an appointed agent(s). Historically firms in the agrochemical industry have been responsible for pesticide distribution in Kenya. The principal importers before 1963 included Pest Control Ltd (founded in England), Murphy Chemicals (a subsidiary of May and Baker), and Shell Chemical Industries (a subsidiary of Shell Oil). The primary pesticide distributors included the Kenya Farmers Association (KFA) and BEA Corporation (owners of Mitchell Cotts and Simpson and Whitelaw Seed Merchants) (Rocco, 1999). The pesticides were used mostly on plantations, estates, and large farms owned by companies or individuals. After 1963 (post independence), most of the large farms were subdivided, and consequently the distribution of pesticides involved more farmers and became more complex, i.e. through cooperative societies. Representatives of overseas pesticide manufacturers are now involved in the importation of pesticides. Additionally they serve as the principal distributors, supplying pesticides directly to the large-scale and estate farmers and providing continuous supply to stockist shops throughout Kenya. The government regulates this sector through the PCPB. Other important groups include the Agrochemicals Association of Kenya (AAK), the Kenya Safe Use Project and the Kenya Environment Secretariat. The AAK was established in 1958 as the Pesticide Chemicals Association of East Africa and was formed when the participants saw the need for a joint approach following discussions with the Ministry of Agriculture. At that time, the government was trying to establish certain standards for local formulations, particularly dusting powders. After the demise of the East African Community in 1977, the name was changed to the Pesticide Chemicals Association of Kenya (Rocco, 1999). Then in 1997, to reflect the broadening interests of its members, the name was changed again to the Agrochemicals Association of Kenya. In 1987, the Association started a training program on the safe use of pesticides. This encouraged the International Group of National Associations of Agrochemical Manufacturers (GIFAP) to start the Kenya Safe Use Project in 1991 (Rocco, 1999). © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts Pesticides in Kenya 57 In the public health sector, pesticides have offered control of vector-borne diseases such as malaria, African sleeping sickness, bilharziasis (an infection by parasitic flukes of the genus Schistosoma Sambon), and fascioliasis (an infection caused by liver flukes of the genus Fasciola L.) through pesticide spray programs aimed at controlling the vectors including mosquitoes, tsetse flies, and water snails. WHO programs to eradicate these pests in areas like Mwea Tabere settlement scheme (an area set aside for rice growing and human settlement), Kano Plain, and Lambwe Valley have rendered them habitable. Historically dieldrin, DDT, and endosulfan were used for the control of mosquitoes and tsetse flies, but due to their detrimental effects on non-target organisms, the less persistent OP, carbamate, and pyrethroid insecticides are now used. Pirimiphos methyl is currently being used to control adult mosquitoes outdoors and permethrin is used for household residual sprays and for treating bed mosquito nets, curtains, and fabrics for protection against mosquitoes and other biting insects. Cyhalothrin-λ is also used in public health for control of houseflies, mosquitoes, and cockroaches. Niclosamide and trifenmorph have been used at Mwea Tabere to control the water snail Biomphalaria pfeifferi Krauss (Gastropoda: Planorbidae), which is a vector of bilharz- iasis. Household pests such as flies, cockroaches, fleas, rats, and mice have been controlled using various products (see Table 4.6). Storage pests Problems associated with storage insect pests on maize in Kenya have existed ever since the crop was first introduced. This is because the high temperatures and relative humidity in most regions of the country strongly favor the growth and development of these pests (Asman, 1966). The infestation trend of harvested crops can be broken into three phases depending on the species attacking the crop and the storage environment. The first phase occurs when the grain is maturing in the field and is characterized by infestations by primary pests, e.g. Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) and Sitotroga cereallela Olivier (Lepidoptera: Gelechiidae) (Floyd, 1971; Ayertey, 1978), which attack whole grain. Ephesta cautella Walker (Lepidoptera: Pyrilidae) is absent from the grain during this phase. Once grain is shelled and placed in the warehouse, E. cautella becomes important in close association with other secondary pests, particularly Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), Corcyra cephalonica Stainton (Lepidoptera: Galeriidae), and Oryzeaphilus surinamensis L. (Coleoptera: Silvinidae) (Delima, 1973). Secondary pests are those that feed on grain already damaged by primary pests and also on fragments of grain. The third phase, in which E. cautella is less important, occurs when control operations are less than optimal and comprises infestations by Rhizopertha dominica Fabricius (Coleoptera: Bostrichidae), Cryptolestes spp. (Coleoptera: Cucujidae), and Tenebroides mauritanicus L. (Coleoptera: Trogositidae) (Graham, 1970a). Attempts to control the pests have relied heavily on the use of pesticides including DDT, γ-BHC, pyrethrins, and malathion, but they have achieved limited © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts 58 S.O. Wandiga, J.O. Lalah and P.N. Kaigwara success (McFarlane, 1969). Presently bromophos, dichlorvos, pirimiphos-methyl, and permethrin are the primary insecticides used, although control is incomplete and the pests still cause significant losses. Pests attacking grain stored on the farm are controlled by residual chemical sprays on storage structures and insecticidal dusting of cob maize (Anonymous, 1974). In contrast, the primary method employed at centralized storage facilities has been fumigation (McFarlane and Table 4.6 Some pesticides used in Kenya (adapted from the Pest Control Products Board) Pesticide common name Type: use λ-Cyhalothrin Insecticide: for use on cotton, horticulture, ornamentals. Carbosulfan (carbofuran or furadan) Insecticide: control of maize stalkborer, coffee berry borer, cotton pests, aphids, thrips, lister scale, soil pests (e.g. termite grubs and nematodes) in coffee nurseries. Seed dressing in beans and maize for the control of soil borne and early foliar pests. Cypemethrin Insecticide: for use on cotton, vegetables, citrus, and other fruits and army worm and locust control. Chlorpyrifos Insecticide: for use on cotton, locust and army worm control, soil pests and larvicide for public health. Carbofuran Systemic insecticide/nematicide: soil pests, nematodes, early foliar feeding pests on coffee, bananas, pineapples, pyrethrum, nurseries, maize. Applied with mechanical granular applicators. Glyphosate Herbicide: post-emergence systemic control of weeds in coffee, tea plantations, sugarcane, pasture destruction, reduced tillage. Copper hydroxide or 50% Fungicide: for the control of Coffee Berry metallic copper Disease (CBD), leaf rust, bacterial blight on coffee, and horticultural crops. Chlorfenvinphos Acaricide: for the control of all species of ticks found in East Africa (vectors of East Coast fever), also fleas, lice on cattle, goats, sheep. Amitraz (N-methylbis Acaricide: for veterinary use to control ticks and (2,4-xylylimino-methyl)amine) other ectoparasites on cattle – 0.025% aqueous dispersion applied as dip or spray at 7 d intervals. Coumatetralyl Rodenticide: for the control of rats and mice. Bacillus thuringiensis Berliner Biological insecticide: for control of var. kurstaki 16 lepidopterous larvae and other pests on vegetables; for the control of giant looper, green looper, leaf skeletonizers, and jelly grub in coffee. Pyrethrin/permethrin/ Insecticide: aerosol for the control of crawling piperonyl butoxide/ dichlorvos and flying insects, cockroaches, ants, flies, mosquitoes. © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando P. Carvalho, Damia Barcelo and Jan Everaarts [...]... of p,p´-DDT in aquaria set up to simulate a tropical marine ecosystem and containing oysters, seawater, and sediments Concentrations of 14C-DDT residues were found to decline very rapidly (within 24 hours) in the water to 70 percent of the initial level and further declined to less than 10 percent after three days Oysters accumulated 14C-DDT at a very fast rate reaching a maximum level in 24 hours,... Klaine, Fernando P Carvalho, Damia Barcelo and Jan Everaarts 78 S.O Wandiga, J.O Lalah and P.N Kaigwara Lalah, J.O., Acholla, F.V and Wandiga, S.O 19 94 The fate of 14C p,p´-DDT in Kenyan tropical soil J Environ Sci Health B 29(1):57– 64 Lalah, J.O and Wandiga, S.O 1996 The persistence and fate of malathion residues in stored beans (Phaseolus vulgaris) and maize (Zea mays) Pest Sci 46 (3):215–20 Lincer,... H.C.B 19 84 Degradation and dissipation of persistent pesticides in the tropics Kenya J Sci Technol 5:31 44 Wandiga, S.O and Mghenyi, J.M 1988 Persistence of 14C-DDT in the tropical soils of Kenya In: Isotope techniques for studying the fate of persistent pesticides in the tropics IAEA TECDOC -4 7 6 Vienna: IAEA, pp 19–26 Wandiga, S.O and Mutere, A 1988 Determination of gamma-BHC in breast milk of Kenyan... aldrin (not detected and 0.02 ppm), dieldrin (0.2 and 0.07 ppm), and lindane (1.19 × 10–3 and 7. 74 × 10–3 ppm) Mean DDT levels were 0.99 and 0 .45 ppm in fat and fillets of Nile perch, respectively, and ranged from 0.002 to 4. 51 mg kg–1 lipid and 0.0 04 to 0.19 mg kg–1 ∑ HCH residues ranged from 0.001 to 0.11 mg kg–1 in Nile perch DDT and its metabolites formed the largest proportion of OC residues in. .. 1988) The main route of exposure to DDT and other OC pesticides in humans is through oral intake, e.g vegetables, beef, and dairy milk containing these residues (Matsumura, 1972; Kanja, 1988) Inhalation of pesticide vapors and consumption of contaminated water are other potential sources, especially in agricultural areas (Kanja, 1988) In one instance, people complained of stomach pains after eating fish... gambiae Giles and its control by two microbial bacterial pathogens [MSc thesis] Department of Zoology, University of Nairobi Nairobi, Kenya Ongeri, D., Wandiga, S.O and Lalah, J.O 1998 The distribution, metabolism and persistence of 14C-DDT and 14C-chlorpyrifos residues in sediment and fish in a model ecosystem In: Proc 7th Int Conf in Africa and 34th Convention of the South African Chemical Institute... Carvalho, Damia Barcelo and Jan Everaarts Pesticides in Kenya 71 Table 4. 11 Dissipation of DDT, DDE, and lindane in Kenyan soils Kenyan soil site Pesticide Half-life (d) Metabolites identified Reference DDT 117 ± 10 DDT, DDE, 4 PCB Wandiga and Natwaluma (19 84) DDT DDT 118 ± 13 98 DDT, DDE, 4 PCB –a DDT DDE Lindane 1st phase 64. 6 145 DDT, DDE, DDD DDE 4 – Nairobi soil 2nd phase 48 88 – DDT Lindane 1st phase... dieldrin and its photo-isomer in game animals after aerial spraying of dieldrin for tsetse fly control in the Lambwe Valley DDT, β-HCH, dieldrin, and heptachlor epoxide have been detected in the adipose tissue of humans in Kenya, with DDT being the main contaminant (Wasserman et al., 1972) The people sampled had no occupational exposure to the pesticides, indicating other sources were responsible Pesticide. .. breams and catfish (0.213 and 0. 145 mg kg–1, respectively) Inland lakes ecosystems ∑ DDT residue levels found in fish from inland lakes are given in Table 4. 9 Lincer et al (1981) found a bottom feeding fish Labeo cylindricus Peters (Cypriniformes: Cyprinidae) from Lake Baringo had a concentration of 0 .4 mg kg–1 ww of p,p´DDE in muscle tissue Munga (1985) also found a maximum mean concentration of DDT in. .. of PCBs and p,p´-DDE Gastropod molluscs and edible penacid prawns had the highest levels of PCBs and p,p´-DDE Freshwater and estuarine ecosystems A study conducted in the Hola irrigation scheme demonstrated a strong correlation between DDT and endosulfan tissue residues and the level of fat in fish (Munga, 1985), Tables 4. 8 (a) and (b) Munga examined pesticide residues of DDT and endosulfan in four . 74. 4 682.6 776 .4 19 94 479.3 286.5 84. 5 43 2.8 1,283.1 1993 42 8.7 272.2 64. 1 44 1.8 1,206.8 1992 505.0 228.5 101.7 45 7.1 1,292.3 1991 202.2 146 .8 41 .8 223.8 6 14. 6 1990 260.3 159 .4 55.6 169.2 644 .5 1989. Lindane was introduced in Kenya in 1 949 , toxaphene in 1950, DDT in 1956, and dieldrin in 1961 (Kaine, 1976). Other compounds in use during the © 2003 Milton D. Taylor, Stephen J. Klaine, Fernando. maize and cotton while other OCs, e.g. lindane, aldrin, and dieldrin, were used for seed dressings. DDT was last imported into Kenya in 1985, aldrin and dieldrin in 1992 (PCPB). OCs still in use in