Chronic Toxicological Effect of 2, 2-dichlorovinyl Dimethyl Phosphate (Sniper) on Some Reproductive and Thyroid Hormones of New Zealand white Rabbits

Aim: To assess the chronic toxicological effect of 2, 2-dichlorovinyl dimethyl phosphate (DDVP, with trade name - sniper) on some reproductive and thyroid hormones of New Zealand white Rabbits.

Study Design: An experimental study.

Place and Duration of Study: Department of Biological Science, Rivers State University, Port Harcourt Animal House, Rivers State Teaching Hospital and Nigerian National Petroleum Corporation Hospital Laboratory, between January, 2020 and April 2020.

Methodology: Thirty-six (36) male New Zealand white rabbits weighing approximately 1.0mg/kg were used for the study. The rabbits were kept in a spacious and well-ventilated cage at room temperature, under natural circadian rhythm and were allowed to acclimatize for fourteen (14) days. They were divided into three (3) groups of four (4) rabbits each with four (4) matched control. For the chronic oral study, 10% of the LD50 (details not included) which is 0.005mg/kg dose of sniper, mixed with 1.0ml of distilled water was administered orally to the rabbits daily for the stipulated period of 0-30, 0-60 and 0-90 days. The matched control rabbits received only feed and water ad libitum during the study. Whilst, for the chronic inhalation study, 10% of the LD50 dose of sniper which is equivalent to 0.05mg/m3 dose of sniper was mixed with 1.0ml of distilled water, sprayed in the closed cages. At day 30, 60 and 90, 4 rabbits were sacrificed each from the chronic oral and inhalation study groups and the matched control group. Blood specimens were collected at each stage, about 5.0mls of blood was collected into lithium heparin specimen container for the investigation of some reproductive and thyroid hormones, which were analyzed using the Enzyme linked immune-sorbent assay method (ELISA). Statistical Package for Social Sciences (SPSS) version 22.0 of windows statistical package, developed by International Business Machines Corporation (IBM), was used to analyze the data generated and p values less than .05 were considered significant.

Results: The results showed that chronic 2, 2-dichlorovinyl dimethyl phosphate exposure in rats caused a statistically significant decrease (P<0.05, F=8.798) in the levels of testosterone: control (3.70 ± 0.46 ng/ml), sniper treated group (1.48 ± 0.22 ng/ml) for the 30days period of oral exposure. Also, there were increases in prolactin levels for oral 30 days exposure (control: 9.03 ± 0.69ng/ml, sniper treated: 14.28 ± 0.67ng/ml), while the levels for the 60 days: control (7.68 ± 1.19ng/ml), sniper treated group (16.00 ± 1.12ng/ml) also significantly increased (P<0.05, F=10.19). Decrease in T4 (control: 6.94 ± 0.35mg/dl, sniper treated: 4.53±0.61mg/dl), significant decrease in FSH, T3 and LH for both oral and inhalation routes of administration and as the duration of exposure increased were also observed. TSH levels also increased significantly for both oral and inhalation routes of administration. Increases and decreases observed in the levels of the parameters were seen to be consistent as the duration of exposure increased.

Conclusion: chronic 2, 2-dichlorovinyl dimethyl phosphate exposure caused a decrease in the levels of testosterone, T4, T3, FSH, LH, while there were increases in the levels TSH and prolactin for both oral and inhalation routes, and across the duration of exposure. This study has also revealed that oral and Inhalation routes of sniper exposure can produce similar toxicit