Survey and assessment of acaricide residue levels in home cattle sprays, soil and water from Ewaso river, Kajiado county, Kenya.

Abstract

Tick borne diseases are a major global concern for livestock productivity. These ectoparasites control involve use of acaricides from which have reported tick treatment failures, increased environmental contamination and enhanced public health concerns. The study aimed at surveying and determining the residue levels of different types of amitraz (2, 4-dimethylaniline), deltamethrin (Br2CA and PBA) and cypermethrin (3-phenoxybenzoic acid (PBA) pesticides used by farmers in Kajiado West Sub County. The parasites are responsible for economic losses that are either direct or indirect in cattle, goats and sheep. Some of the direct losses are as a result of discomfort and damage caused by parasites resulting to drop in milk production and damage to wool and hides. For proper understanding, researcher surveyed on information concerning pesticides usage, assessed levels of training on acaricides use, commonly experienced livestock diseases, control strategies, dilution modalities, preferred mode of application, health effects upon application and fate. Cross-sectional design using a structured questionnaire, face to face interviews and focus group discussions with 138 farmers in Magadi and Olkkeramatian locations, 38 willing farmers participated in questionnaire from which ten selected farmers’ homesteads were used. Description statistic was carried for frequencies, percentages, variance and data subjected to confidence limits to T-test at 95 %. 1.0 L of freshly prepared homemade cattle sprays samples were collected by grab method into amber glass bottles. In addition, 100 g of soil samples were collected (0-30 cm) plough layers for pesticide residue level analysis. Soil samples for dissipation studies were also collected at the sites where the farmers sprayed their animals on day 0, 1, 2, 3, 4, 5, 7 and 10. Water samples were collected from the southern tributary of Ewaso Nyiro River in 2.5 L amber bottles by grab method. All the samples were collected during the dry and wet seasons. Soil samples were Soxhlet extracted with acetone: hexane (1:3) while Water samples and homemade cattle sprays were liquid-liquid extracted with dichloromethane as solvent, cleaned and analysed by gas chromatography mass spectroscopy at the University of Nairobi, Chemistry Department. Results from the interview revealed that farmers applied nine (9) acaricides under different trade names on their livestock. The major three acaricides used by the farmers were those with the following active ingredients (a.i) cypermethrin (76%), amitraz (72 %), and deltamethrin (46%). The acaricides were WHO class II (33.3 %) and WHO class III (67.7 %) respectively. Amitraz was found to be the most preferred acaricide compared to synthetic pyrethroids though some mixed the acaricides to improve efficacy. Farmers were too familiar with local names of different livestock diseases that are majorly controlled by hand spraying through use of privately owned knapsack sprayers within the cattle sheds. The concentration of the homemade cattle sprays ranged from 3,884±25.3 to 12,236 ± 145.4 μg/L for amitraz, 3,834±80.2 to 11,972 ± 74 μg/L for cypermethrin and 3,879±33.2 to 12,298 ± 82.1 μg/L for deltamethrin while the residue levels of these pesticides were below the detection limits (BDL) in all the river water samples. The half-life of amitraz range in soil was (0.44 - 1.60) days, cypermethrin (0.70 – 3.30 days) and deltamethrin (0.74 – 1.30 days). The analysis revealed that homemade cattle sprays in the sub-county had low concentrations of amitraz, cypermethrin and deltamethrin than those recommended by the manufacturers (50-400 mg/L) indicating that the acaricides were over diluted leading to the observed tick re-occurrence. Thus there is need for the agrochemicals and the county government of Kajiado to train the farmers on how to prepare the homemade cattle sprays to ensure efficient tick control. The observed disposal practices of unused acaricides and containers after use have great potential to cause environmental pollution and by extension affect human health.