Effects of Subchronic Exposure via Drinking Water to a Mixture of Eight Water-Contaminating Metals: A Biochemical and Histopathological Study in Male Rats

Abstract

In the current study, we examined whether subchronic exposure via drinking water to low doses of a mixture of metals (arsenic, cadmium, lead, mercury, chromium, manganese, iron, and nickel), found as contaminants in various water sources of India, and to concentrations equivalent to WHO maximum permissible limits (MPL) in drinking water for individual metals, can alter systemic physiology of male rats. Data on water contamination with metals in India were collected from the literature and metals were selected on the basis of their frequency of occurrence and contamination level above MPL. Male Wistar rats were exposed to the mixture at 0, 1, 10, and 100 times the mode concentrations (the most frequently occurring concentration) of the individual metals via drinking water for 90 days. One more group of rats was exposed to the mixture at a concentration equivalent to the MPL (WHO) in drinking water for individual metals. Toxic potential of the mixture was evaluated by assessing general toxicological end points, serum chemistry and histopathology of vital organs. The mixture decreased body weight and water consumption and increased weights of brain, liver, and kidneys with 10x and 100x doses. After 30 days of exposure, no appreciable changes were found in any blood clinical markers. After 60 days, only the 100x dose, while after 90 days both 10x and 100x doses increased activities of aspartate aminotransferase and alkaline phosphatase and levels of urea nitrogen and creatinine and decreased total protein and albumin levels, but alanine aminotransferase activity and glucose level were not affected. At 10x and 100x exposure levels, qualitatively similar, but dose-dependent vascular, degenerative, and necrotic changes were observed in brain, liver, and kidney. The results indicate that subchronic exposure to the metal mixture affected general health of male rats by altering the functional and structural integrity of kidney, liver, and brain at 10 and 100 times the mode concentrations of the individual metals in Indian water sources, but exposure at mode concentrations of contemporary water contamination levels or at concentrations equivalent to the MPL for individual metals in drinking water may not cause any health hazards in male rats.

Effect of Sub-Chronic Exposure to Chromium on Haematological and Biochemical Parameters of Male Albino Rat

“…This indicated that chronic treatment with potassium dichromate resulted in a general toxic effect in the animals. The increase in the weight of the liver and kidney coupled with decrease in body weight gain due to chronic exposure to chromium at low-dose level indicates general toxic effect of such exposure on male rats [15]. This suggested that chronic chromium exposure resulted in a nutritional disturbance in treated rats [16].…”

A multibiomarker approach in rats to assess the impact of pollution on Sinos River, Southern Brazil

“…Contaminated rivers often contain a wide variety of organic and inorganic pollutants, including potentially toxic metals such as Pb, Cd, Fe, Zn, Cu, Mn, Mo, and Cr (Sánchez-Chardi et al, 2007). Oxidative stress may be attributed to these elements, producing a variety of alterations in tissues (Jadhav et al, 2007 ). However, tissue damage can occur by means of several mechanisms and our findings suggest that the liver damage observed in the exposed animals was not related to lipid peroxidation, since no increase in MDA levels was observed.…”

Evaluation ofMoringa oleiferaleaf in laying hens: effects on laying performance, egg quality, plasma biochemistry and organ histopathological indices

“…The formalin-fixed liver and kidney samples were stained with haematoxylin and eosin according to the method of Jadhav et al (2007). All reagents used were of analytical grade (Sinopharm Chemical Reagent Beijing Co., Ltd, Beijing, China).…”