Chromium Toxicity in Small Indian Mongoose (Herpestes Javanicus) Inhabiting Tanneries Area of Kasur, Pakistan.

Abstract

Chromium (Cr), widely used in leather tanning industries, is a potent toxic metal which can accumulate in the animal body and adversely affect functioning of various body systems including the reproductive organs. District Kasur, Pakistan, is famous for having leather tanneries industry where more than 270 individual tanneries are working at the moment. As a result of tanning activity, chromium is directly discharged untreated into the surrounding environment, adjoining water nullahs (a small canal or drain carrying polluted water from tanneries to the main streams outside), causing contamination of the habitat. Resultantly, wildlife species, reliant on these water sources, are exposed to chromium toxicity; whereby chromium is taken up into the animal body through drinking water and food chain. The current study investigated the toxic effects of chromium uptake from environment on the gonadal tissues (testes and ovaries) of small Indian mongoose (Herpestes javanicus) inhabiting the tannery area. The sludge and waste water were sampled from the study area for estimation of chromium levels in the environment. Moreover, adult animal specimens (mongooses) were live trapped from the experimental area to collect blood and gonadal tissues (male and female) along with kidney and liver samples for quantification of chromium concentration through atomic absorption spectrophotometer (AAS). Blood samples of the animals were centrifuged to collect plasma for estimating the concentrations of reproductive hormones (testosterone, estradiol and progesterone) as well as gonadotropins (Luteinizing hormone, LH and Follicle stimulating hormone, FSH). The testes and the ovary samples of mongooses were processed for standard histological procedure to investigate any cellular alterations in the reproductive organs. Average chromium concentrations, in experimental area soil and water, and the blood and tissue samples of the mongooses, were found significantly higher (p ˂ 0.0001) when compared to control samples. Blood plasma testosterone and Luteinizing Hormone (LH) levels were significantly reduced (p ˂ 0.0001) male mongooses from the study area. The concentrations of Progesterone and Estradiol were found significantly decreased and the concentrations of FSH and LH significantly elevated (p ˂ 0.0001) in female mongooses from the study area. Average body weights of animal specimens, and also the weights of testes and ovaries of experimental animals were found significantly (p ˂ 0.0001) reduced while compared to the control animal samples. Gonadosomatic index (GSI) in the male small Indian mongooses were found significantly elevated (p < 0.001) but in females it was found decreased while the Hepatosomatic index (HSI) in both male and female mongooses were found significantly high (p < 0.001) as compared to control. Histological analysis revealed disorganization of seminiferous tubules inside the testes of the chromium exposed animals, along with depleted germ cells and hyperplasia of the Leydig cells. Sperm counts inside seminiferous tubules were found significantly reduced (p ˂ 0.0001) and the spaces among the seminiferous tubules significantly increased. The H&E stained sections of ovaries of mongooses showed significantly reduced numbers of follicles at all follicular stages; vacuolization and depletion in cell contents were noticeable along with abnormal follicle and ovum growth. The study concludes that chromium being discharged from tanneries into the environment of the Kasur District, is up taken by the small Indian mongooses naturally inhabiting the study area; leading to chromium deposition in their body tissues, significantly reduced concentrations of the reproductive hormones, and altered cellular morphology of the testes and ovaries, and posing a serious potential threat to reproductive functioning of the species.