Exposure to organophosphate pesticides and thyroid function: A systematic review

Abstract

Organophosphate pesticides (OPs) are widely used for various agricultural, industrial and domestic purposes. Long-term exposure to  these products leads to several health problems, including a potential disruption of the thyroid gland as suggested by recent studies. The  purpose of this review is to examine the published scientific evidence on this effect. A systematic review of articles published  between 1970 and 2019 was conducted using the PubMed and ScienceDirect databases. Twenty-two studies were included in this review:  4 human studies, 16 in vivo studies and 2 in vitro studies. Almost all in vivo studies have shown impaired thyroid function with decreased  T3 and T4 hormones and increased TSH levels, reflecting hypothyroidism. The findings from human studies converge with in vivo tests  regarding the presence of a disruption in thyroid hormones, but diverge in the direction of this disruption. In the 2 in vitro studies,  dysthyroidism was induced by OPs, although the diagnostic tools were different, in terms of cell lines or parameters explored. Studies on  the impact of OPs on thyroid function remain insufficient. More clinical and empirical studies are needed with a standardized  methodology that allows the comparison of the results of several studies.