Thyroid Disrupting Effects of Old and New Generation PFAS

Abstract

Per- and polyfluoroalkyl substances (PFAS) represent a group of synthetic compounds widely used in industry plants due to their low grade of degradation, surfactant properties, thermic and flame resistance. These characteristics are useful for the industrial production, however they are also potentially dangerous for human health and for the environment. PFAS are persistent pollutants accumulating in waters and soil and recoverable in foods due to their release by food packaging. Humans are daily exposed to PFAS because these compounds are ubiquitous and, when assimilated, they are difficult to be eliminated, persisting for years both in humans and animals. Due to their persistence and potential danger to health, some old generation PFAS have been replaced by newly synthesized PFAS with the aim to use alternative compounds presumably safer for humans and the environment. Yet, the environmental pollution with PFAS remains a matter of concern worldwide and led to large-scale epidemiological studies both on plants’ workers and on exposed people in the general population. In this context, strong concern emerged concerning the potential adverse effects of PFAS on the thyroid gland. Thyroid hormones play a critical role in the regulation of metabolism, and thyroid function is related to cardiovascular disease, fertility, and fetal neurodevelopment. In vitro, ex vivo data, and epidemiological studies suggested that PFASs may disrupt the thyroid hormone system in humans, with possible negative repercussions on the outcome of pregnancy and fetal-child development. However, data on the thyroid disrupting effect of PFAS remain controversial, as well as their impact on human health in different ages of life. Aim of the present paper is to review recent data on the effects of old and new generation PFAS on thyroid homeostasis. To this purpose we collected information from in vitro studies, animal models, and in vivo data on exposed workers, general population, and pregnant women.

Per- and Polyfluoroalkyl Substances (PFAS) in Integrated Crop–Livestock Systems: Environmental Exposure and Human Health Risks

“…However, several studies have shown an association with various adverse health issues in humans with exposure to PFAS. Effects on renal health, endocrine function, metabolism and bone health have been well studied and reported [ 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. The health effects of intrauterine exposure to PFAS have also been investigated [ 50 , 61 , 62 , 63 , 64 ].…”

Exposure to Perfluoroalkyl Substances During Pregnancy and Fetal BDNF Level: A Prospective Cohort Study

“…PFAS interfere TH synthesis, affecting TPO function and iodine uptake. PFAS exposure during pregnancy seems to cause slight but statistically significant alterations in thyroid function parameters, both in mothers and newborns (58). Both legacy PFAS and some new PFAS alternatives that were not included in our PFAS detection profiles such as hexafluoropropylene oxide dimer acid (HFPO-DA or GenX) and 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) display a highly toxic profile on thyroid cells through promoting DNA-damage and affecting the expression of thyroid transcription-factor genes (59,60).…”

Early-Life Exposure to Per- and Poly-Fluorinated Alkyl Substances and Growth, Adiposity, and Puberty in Children: A Systematic Review

“…PFAS have been identified as thyroid disrupting chemicals, potentially affecting hypothalamic-pituitary-thyroid axis, thyroid hormone synthesis and metabolism ( 119 , 120 ). Since thyroid hormones play a crucial role in normal growth and development, altered thyroid function can affect early-life growth and adiposity during critical periods of development.…”