Detrimental Effects of Mosquito Coil Smoke Exposure on Memory and Hippocampal Morphology

Mosquito coil smoke is widely used to repel mosquitoes and prevent malaria in many malaria-endemic regions. While there is considerable awareness of the toxicity of carbon monoxide (CO), exposure to CO from less obvious sources like MC smoke is often overlooked. This study investigates the neurotoxic effects of mosquito coil smoke in mice. In this study, sixteen adult male mice were randomly divided into two groups: an experimental group and a control group, each comprising 8 mice. The experimental group was exposed to MC smoke (Wavetide, China) for 15 minutes daily over a period of 14 days, inside a gas chamber (length 75x breadth 50x height 50cm). A digital CO meter (PCMM05 Pyle) was employed to measure CO gas levels within the chamber. Our findings indicate that burning an MC for 15 minutes produces an average of 312 parts-per-million (ppm) of CO, significantly elevating blood carboxyhemoglobin (COHb) levels by 15.8%. These levels greatly exceed the World Health Organization's recommended limits of CO exposure (<100 mg/m³ or 87 ppm for 15 minutes) and COHb levels (<2%). Furthermore, MC smoke exposure was linked to impaired learning and memory and extensive apoptosis of brain cells. However, body weight was unaffected. Despite the widespread use of MCs for malaria prevention, they could represent a significant source of CO and other neurotoxins, posing a potential threat to human health. The health risks associated with their use are frequently underestimated, even by public health professionals.

Key Words: Mosquito coil, carbon monoxide, neurotoxicity, learning and memory, hippocampus