Repeated-dose 14-day dermal toxicity of different combinations of some synthetic pyrethroid insecticides, piperonyl butoxide, and tetramethrin in rats

The aim of this study was to evaluate the repeated-dose 14-day dermal toxicity of different combinations of some synthetic pyrethroid insecticides, piperonyl butoxide, and tetramethrin in rats. A total of 70 adult Wistar rats were randomly divided into 7 (6 experimental and 1 control) groups. Different combinations of insecticides were dermally applied to the rats in the experimental groups for 14 days. Clinical observations were performed daily; hematologic and biochemical parameters were also determined. Gross necropsy and histopathologic examinations were performed systematically, and organ weights were recorded. Although the administered doses of the insecticides were relatively lower than their acute dermal toxicity values, a high mortality rate (27 of 60 experimental animals, 45%) was observed. Furthermore, the insecticide combinations caused decreased body weights and feed consumptions, increased organ weights, and hematologic, biochemical, and common histopathologic changes. As a result, the findings showed that although pyrethroids are considered to be of low acute toxicity, they become more toxic when combined with piperonyl butoxide or tetramethrin in certain doses.