Investigation of the behavioral and neurotoxic effects of sub-chronic exposure of Wistar rats to treated crude oil exploration water (produced water)

Abstract

Treated crude oil exploration water (TCOEW) is a significant byproduct created from petroleum exploration activities and is known to be a complicated synthesis of numerous dangerous chemical materials. This study is designed to evaluate the behavioral and neurotoxic effects of sub-chronic exposure of Wistar rats to treated crude oil exploration water (produced water). Fifty rats were randomly assigned to five treatment groups, with ten rats per group, and treated with five concentrations (1%, 5%, 10% and 20%) of TCOEW. Each TCOEW concentration was administered for 90 days ad-libitum as normal drinking water to each group, while the control group was given tap water. After sub-chronic exposure of 90 days, the behavioral effect of TCOEW was investigated using open field test (novelty-induced behavior), elevated plus maze (anxiety), novelty object recognition test (short-term memory) Morris water maze (spatial memory), and the neurotoxic effects by biochemical and histological assessment of the brain. Data were analysed using descriptive statistics and ANOVA at α 0.05. TCOEW produced a significant (p < 0.05) reduction in novelty-induced rearing, grooming, and locomotion. Also, TCOEW reduced the index of open arm entry IOAA in EPM, and time spent exploring the novel object in NORT. TCOEW-exposed groups had significantly higher annulus time and higher annulus crossing in Morri’s water maze. This study provides evidence that the treated crude oil exploration water might contain chemicals, which on chronic exposure, have effect on behavior, learning and memory and anxiety.