Developmental Neurotoxicity of Pyrethroid Insecticides: Critical Review and Future Research Needs

Abstract

Pyrethroid insecticides have been used for more than 40 years and account for 25% of the worldwide insecticide market. Although their acute neurotoxicity to adults has been well characterized, information regarding the potential developmental neurotoxicity of this class of compounds is limited. There is a large age dependence to the acute toxicity of pyrethroids in which neonatal rats are at least an order of magnitude more sensitive than adults to two pyrethroids. There is no information on age-dependent toxicity for most pyrethroids. In the present review we examine the scientific data related to potential for age-dependent and developmental neurotoxicity of pyrethroids. As a basis for understanding this neurotoxicity, we discuss the heterogeneity and ontogeny of voltage-sensitive sodium channels, a primary neuronal target of pyrethroids. We also summarize 22 studies of the developmental neurotoxicity of pyrethroids and review the strengths and limitations of these studies. These studies examined numerous end points, with changes in motor activity and muscarinic acetylcholine receptor density the most common. Many of the developmental neurotoxicity studies suffer from inadequate study design, problematic statistical analyses, use of formulated products, and/or inadequate controls. These factors confound interpretation of results. To better understand the potential for developmental exposure to pyrethroids to cause neurotoxicity, additional, well-designed and well-executed developmental neurotoxicity studies are needed. These studies should employ state-of-the-science methods to promote a greater understanding of the mode of action of pyrethroids in the developing nervous system.

Characterization of the molluscicidal activity of Bauhinia variegata and Mimusops elengi plant extracts against the fasciola vector lymnaea acuminata

“…One of the possible solutions to control fasciolosis is to disrupt the life cycle of Fasciola by killing the vector snail 1,[9][10][11]27,35 . The continuous and indiscriminate use of synthetic molluscicides for the control of vector snails has created a long detrimental effect on the aquatic environment 22 . Therefore, there is a need to develop a safe and eco-friendly counterpart of synthetic molluscicides.…”

Residential insecticide usage in northern California homes with young children

“…Understanding behavioral patterns of residents, particularly those with young children, is especially important as critical time windows in early development lead to higher vulnerability to the toxicity of insecticides. In addition, typical children's behaviors such as increased hand to mouth activity and crawling on floors and carpets result in higher exposures as well as internal doses (Landrigan et al, 1999;Shafer et al, 2005;Rosas and Eskenazi, 2008).…”

Insect Repellants During Pregnancy in the Era of the Zika Virus

“…High exposures can lead to acute neurotoxicity with symptoms of nausea, vomiting, shortness of breath, and seizures. 36 Pyrethroids are also lipophilic and have the potential to accumulate in the brain and fat and be transferred to breast milk.…”

“…36 Given that the nerve cell is the target for pyrethroids, a particular concern is the potential neurotoxicity of pyrethroids to the very young. Experimental animal data suggest that prenatal pyrethroid exposure may adversely affect learning and behavior, but exposures are much higher in such experiments than in typical human exposures and metabolism may be quite different.…”