Toxicological Effects of Chronic Inhalation Exposure of 2-2 Dichlorovinyl Dimethyl Phosphate on Haematological Indices of New Zealand White Rabbits

Aim: To assess the Toxicological Effects of Chronic Inhalation Exposure of 2-2 dichlorovinyl dimethyl phosphate on Haematological indices of New Zealand white Rabbits.

Study Design: This is an experimental study.

Methodology: A total of twenty four male New Zealand white rabbits, two months old weighing between 1.0 and 1.2 kg, were used for the study. They were divided into three (3) groups, each consisting of four (4) rabbits and a corresponding number of matched controls, for long-term toxicological effects of dichlorvos on the rabbits (30 days, 60 days and 90 days).The rabbits received ten (10%) of the LD50 dose . The LD50 dose was 0.5 mg/m3, while 10% of the median lethal dose of dichlorvos which was 0.05 mg/m3 was diluted with 1.0 milliliter of distilled water. It was administered by spraying in a closed cage containing the rabbits every day for thirty, sixty, and ninety days. At the end of each month, a set of rabbits in the experimental group with their matched control were sacrificed using chloroform. Five milliliters (5 mls) of blood was collected from each rabbit at the stipulated period for haematological investigations which included the following indices: Total White Blood Cells, Red Blood Cells Count, Hemoglobin, Mean Corpuscular Volume, Mean Corpuscular Hemoglobin, Mean Corpuscular Hemoglobin Concentration, Platelets Count, Neutrophils, Lymphocytes, Eosinophils, Monocytes and Basophil. They were analyzed using an automated haematology analyzer (Sysmex XP-300 automated CBC Hematology Analyzer) Coulter). Data generated were expressed as mean +SD. ANOVA and Tukeys multiple comparison test were used to compare the results between means of groups. Variation in mean of parameters were considered statistically significant at P<0.05.

Results: The results of the haematological indices at 30, 60 and 90 days exposure showed significant decreases in the following parameters: PCV (32.75±1.71%, 32.50±1.29%, 27.75±1.26%) WBC: (3.03±0.43 x 109 /L, 2.10±0.14 x 109 /L, 1.68±0.30 x 109 /L), PLT 48.58±2.42%, 36.28±5.03%, 24.98±29.31%) count, MCV: (70.00±0.82fl, 63.00±2.16fl, 58.50±2.65fl ,MPV: (5.59±0.36fl,63.00±2.16fl, 58.50±2.65fl) and neutrophils. Lymphocytes, Basophils, Monocytes and Eosinophils were significantly increased as the duration of exposure increased from 30 to 90 days.

Conclusion: Dichlorvos caused severe alteration in the haematological parameters of rabbits and the severity of the changes were dependent on the duration of exposure.