D-trans-allethrins in Some Selected Mosquito Coil Repellents Causes Histological Inflammation in Trachea of Experimental Animals

Background: Many reports on the toxicity of some mosquito repellents have been recorded, however, its effect on the trachea.

Aim: This study was aimed at determining the Histopathological and Morphological changes in Trachea of Wistar rats exposed to selected mosquito repellents commonly used in Sokoto, Nigeria especially after the recent outbreak of Malaria and Dengue fever.

Methods: Mosquito repellent brands of Pyrethroids-containing mosquito coil, aerosolized spray and Dichlovors aerosolized spray were studied over 21 days. Rats were exposed to the fumes in coils and aerosolized insecticidal spray for 5 minutes each day, in a well-ventilated box. Control rats were not exposed. Animals were sacrificed on days 7, 14 and 21 post-exposure.

Results: Early observable behavioural signs include irritation, scratching of the eyes and nostrils; in later stages of exposure, sneezing, ruffled fur and lethargy were observed. Gross changes were not apparent in most organs, except for frothy trachea observed in few Wistar rats exposed to the fumes. Histopathology revealed varying degrees of epithelial disruption, lymphocytic infiltration and vascular congestion; more apparent 7 days post-exposure and to a lesser degree, 21 days post-exposure. The severity of the macroscopic changes was more in the first 14 days of exposure while it was reduced in rats that were exposed for 21 days. The most obvious changes were observed in coil repellents containing Rich-d-Trans allethrin.

Conclusion: Acute exposure to fumes of mosquito repellents containing rich-d-trans allethrin is irritating to the trachea and could lead to possible respiratory problems.