Pyrethroids in indoor air during application of various mosquito repellents: Occurrence, dissipation and potential exposure risk
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Published on: March 16, 2019
Huizhen Li1, Michael J Lydy2, Jing You1
1State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Abstract:
Commercial mosquito repellents (MRs) are generally applied as mosquito coils, electric vaporizers (liquid and solid) or aerosol spray, with pyrethroids often being the active ingredients. Four types of MRs were applied individually in a 13-m(2) bedroom to study the occurrence, dissipation and risk of pyrethroids in indoor environments. Total air concentrations (in gas and particle phases) of allethrin, cypermethrin, dimefluthrin and tetramethrin during MR applications were three to six orders of magnitude higher than indoor levels before the applications, and allethrin emitted from a vaporizing mat reached the highest concentration measured during the current study (18,600 ± 4980 ng m(-3)). The fate of airborne pyrethroids was different when the four MRs were applied. Particle-associated allethrin accounted for 95% of its total concentration from the aerosol spray, and was significantly higher than the vaporizing mat (67%), suggesting that the released phase of MRs and size distribution of pyrethroid-carrying particles played important roles in the gas-particle partitioning process. In addition, air exchange through open windows more effectively reduced the levels of indoor pyrethroids than ventilation using an air conditioner. The inhalation risk quotients (RQ) for allethrin derived from application of the vaporizing mat ranged from 1.04 ± 0.40 to 1.98 ± 0.75 for different age-subgroups of the population, suggesting potential exposure risk. Special attention should be given concerning indoor exposure of pyrethroids to these vulnerable groups.
Insights
Commercial mosquito repellents containing pyrethroids can significantly increase indoor air concentrations. Allethrin from a vaporizing mat poses a potential inhalation risk, especially for vulnerable populations, highlighting the need for careful indoor use.
Area of Science:
- Environmental Chemistry
- Toxicology
- Indoor Air Quality
Background:
- Commercial mosquito repellents (MRs) commonly use pyrethroids as active ingredients.
- MRs are available in various forms, including coils, vaporizers, and aerosol sprays, for indoor use.
Purpose of the Study:
- To investigate the occurrence, dissipation, and potential risks of pyrethroids in indoor environments following the application of different MRs.
- To compare the effectiveness of natural ventilation (open windows) versus air conditioning in reducing indoor pyrethroid levels.
Main Methods:
- Four types of commercial MRs were applied individually in a controlled 13-m² bedroom.
- Air concentrations of specific pyrethroids (allethrin, cypermethrin, dimefluthrin, tetramethrin) were measured in both gas and particle phases.
- Inhalation risk quotients (RQ) were calculated for different population subgroups.
Main Results:
- Indoor pyrethroid concentrations increased by three to six orders of magnitude during MR application.
- Allethrin from a vaporizing mat reached the highest measured concentration (18,600 ± 4980 ng m⁻³).
- The phase of release (gas vs. particle) and particle size influenced pyrethroid partitioning; aerosol sprays had 95% particle-associated allethrin.
- Open windows were more effective than air conditioning in reducing indoor pyrethroid levels.
- Inhalation risk quotients for allethrin from vaporizing mats indicated potential exposure risks (RQ > 1) for certain age groups.
Conclusions:
- The application of commercial mosquito repellents significantly elevates indoor pyrethroid levels.
- The form of MR application affects pyrethroid partitioning between gas and particle phases.
- Natural ventilation is more effective than air conditioning for mitigating indoor pyrethroid exposure.
- Vulnerable populations may face significant inhalation risks from certain pyrethroids, necessitating caution and further investigation.
