Pesticides With Potential Thyroid Hormone-Disrupting Effects: A Review of Recent Data

Abstract

Plant Protection Products, more commonly referred to as pesticides and biocides, are used to control a wide range of yield-reducing pests including insects, fungi, nematodes, and weeds. Concern has been raised that some pesticides may act as endocrine disrupting chemicals (EDCs) with the potential to interfere with the hormone systems of non-target invertebrates and vertebrates, including humans. EDCs act at low doses and particularly vulnerable periods of exposure include pre-and perinatal development. Of critical concern is the number of pesticides with the potential to interfere with the developing nervous system and brain, notably with thyroid hormone signaling. Across vertebrates, thyroid hormone orchestrates metamorphosis, brain development, and metabolism. Pesticide action on thyroid homeostasis can involve interference with TH production and its control, displacement from distributor proteins and liver metabolism. Here we focused on thyroid endpoints for each of the different classes of pesticides reviewing epidemiological and experimental studies carried out both in in vivo and in vitro. We conclude first, that many pesticides were placed on the market with insufficient testing, other than acute or chronic toxicity, and second, that thyroid-specific endpoints for neurodevelopmental effects and mixture assessment are largely absent from regulatory directives.

The Role of the Thyroid Axis in Fish

“…Thyroid disruption by exposure to environmental toxicants such as metals [e.g., cadmium ( 384 )], pesticides [e.g., organophosphorous pesticides ( 385 )], and pollutants [e.g., polychlorinated biphenyls, PCBs ( 386 )] could result in increased larval mortality and developmental deficiencies ( 387 ) depending on the aquaculture system and species.…”

Impact of DDT residues in feed on thyroid gland and liver secretory activity of Aberdeen-Angus cattle depending on cattle age and sex

“…In addition, thyroid hormones in the body of young animals have a general metabolic effect, which is associated with their ability to penetrate the lipophilic layer of the cell membrane and interact with steroid hormone receptors in the nucleus, affecting gene expression. Hormone receptors can also bind to DDT molecules, responding to them with a hormone-like effect, which affects changed secretory activity of the thyroid gland (Mughal et al, 2018;Leemans et al, 2019). However, the impact of organochlorines on thyroid secretion activity may diversely lead to hypothyroid (in rats or grey seals: Tebourbi et al, 2010;Sormo et al, 2005) or hyperthyroid (in cats or pigeons: Engadahl et al, 2017;Shrestha et al, 2018).…”

Integrated Approach to Evaluate the Association between Exposure to Pesticides and Idiopathic Premature Thelarche in Girls: The PEACH Project

“…Also relevant is the interaction with the pregnane X receptor that entails the implication of pesticides on cellular metabolism and the detoxification process by regulating the transcription of genes involved in the microsomal cytochrome P450 and conjugation enzymes (i.e., fenbuconazole, tebuconazole), thus possibly affecting steroid hormones homeostasis. The thyroid homeostasis and signaling are also affected by mancozeb, zineb, dimethoate, trichlorfon and malathion with adverse impact on hypothalamus-pituitary-thyroid axis [11].…”