Table 1.

Overview of the groups of EDCs included in this review

Group	Physical and chemical properties	Example	Common route of exposure	Use in products	Production/regulatory status	Toxicity/mechanism of action
PCBs	209 congeners distinguished by number and position of chlorine atoms substituted on the biphenyl moiety Resistant to acids, bases and heat Most are lipophilic and very persistent	3,3′,4,4′,5-Pentachlorobiphenyl (PCB-126)	High-fat food (dairy, meat, fish)	Mixtures have been used in electrical equipment, surface coatings, inks, adhesives, flame retardants and paints	PCB production was banned by the US Congress in 1979 and by the Stockholm Convention on Persistent Organic Pollutants in 2001 Due to their persistence in the environment, there are still concerns	The chlorination pattern determines the toxicity. Mechanisms of action depend on chlorine substitution pattern of congener: oestrogenic, anti-oestrogenic, neurotoxic, dioxin-like Dioxin-like PCBs are ligands to the AH receptor, while many non-dioxin-like PCBs bind to PXR and CAR
Organochlorine pesticides	Insecticidal properties Highly lipophilic Many are very persistent	DDT and its main metabolite p,p′-DDE Hexachlorobenzene Several chlordanes	High-fat food (dairy, meat, fish)	DDT was first used during World War II to control lice-borne typhus Subsequently, farmers used DDT to control agricultural pests	DDT was banned in the USA in 1973 and also in some other countries but is still in use in countries with malaria	Wide range of toxic effects p,p′-DDE, the most environmentally relevant DDT derivative, binds to androgen receptor and has anti-androgenic properties
Dioxins	A diverse range of chemical compounds 419 dioxins and related compounds have been identified Lipophilic Some are very persistent	TCDD	Soil, dairy, meat, seafood	Not used in products Formed during the combustion of wastes or are undesirable byproducts in the manufacture of herbicides, disinfectants and other agents	Covered by the Stockholm Convention on Persistent Organic Pollutants	Wide range of toxic effects, including immune toxicity, developmental and neurodevelopmental effects and changes in thyroid and steroid hormones and reproductive function Only about 30 dioxins are considered to have significant toxicity, with TCDD being the most toxic Mechanisms of action and toxicity vary depending on the chlorine substitution pattern of the congener: oestrogenic, anti-oestrogenic, neurotoxic, dioxin-like The dioxin-like effect is mediated by activation of the AH receptor
BFRs	Widely varying chemical properties At high temperatures, BFRs have an inhibitory effect on combustion chemistry Some are lipophilic and very persistent	Main classes are PBDEs, HBCDDs, TBBPA and other phenols, and PBBs	High-fat food (dairy, meat, fish)	Used in plastics and textile applications, electronics, clothes and insulation in buildings and furniture	The use of certain BFRs is banned or restricted in the EU In the USA, the manufacture of PBB was banned in 1976 Due to the persistence of BFRs in the environment, there are still concerns	Toxic effects, including teratogenicity, carcinogenicity and neurotoxicity, have been observed for some BFR congeners (especially PBDEs) There is evidence that some BFRs disrupt the thyroid hormone system–most data are available for the PBDE class
PFASs	Hydrophobic and lipophobic Some are resistant to environmental degradation and are extremely persistent	Perfluorocarboxylic acids (e.g. PFOA, sometimes called C8, and PFNA) and perfluorosulfonates (e.g. PFOS and PFHxS)	Seafood, drinking water and food contact material	Used in industry and consumer products since the 1950s Used in food packaging materials, non-stick cookware, water-resistant clothing, cleaning products, paints, varnishes and sealants, firefighting foam and cosmetics	Use of PFASs has been largely phased out of food packaging materials The European Parliament has approved an EU directive (2006/122/EU) with restrictions on marketing and use of PFOS and PFOS-related substances	There is evidence that some PFASs disrupt the thyroid hormone system. Some PFASs bind to PPAR-α and to a lesser degree to PPAR-γ.
Bisphenols	Group of non-persistent chemicals with two phenolic rings joined together by a bridging carbon or other chemical structure.	Bisphenol A (BPA; 4,4′-isopropylidenediphenol)	Ubiquitous	Commonly used to produce plastics BPA is used mainly in the manufacture of polycarbonate and is also used in other plastics as a hardener Used in products such as DVDs, dental materials and lunch boxes Epoxy plastic can be used in electronics, building materials, in the protective lining in cans and in the relining of water pipes BPA is present in thermal paper	Controversial issue BPA is banned in baby bottles throughout the EU In 2017, 5.4 million tons of BPA was produced	Initially BPA was designed as a synthetic oestrogen and has been shown to bind to oestrogen receptors (ERα, ERβ, and to the membrane ER) Emerging data shows that BPA interacts with other hormone receptors, including androgen receptors and the thyroid hormone receptor
Phthalates	Esters of phthalic acid Not persistent	DEHP	Ubiquitous	Used as plasticisers in the production of plastics Used in cosmetics, perfumes, pharmaceutical tablets, medical tubing, nutritional supplements, adhesives, paints, food containers and wrappers, toys and cleaning materials	Controversial issue Some countries have banned their use in children’s toys Five million tons of phthalates are produced annually	MEHP, a metabolite of DEHP, has been found in exposed organisms and interacts with all three PPARs

These EDCs were selected because they can be analysed in a valid way either in plasma/serum or in the urine, thereby enabling the evaluation of the health effects of exposure in epidemiological studies

Congeners: congeners are related chemical substances, related to each other by origin, structure, or function

AH, aryl hydrocarbon; CAR, constitutive androstane receptor; EU, European Union; HBCDD, hexabromocyclodecane; MEHP, mono-ethyl-hexyl-phthalate; PBB, polybrominated bisphenol; PBDE, polybrominated diphenyl ether; PFHxS, perfluorohexasulfonate; PFOA, perfluorooctanoic acid; PXR, pregnane X receptor; TBBPA, tetrabromobisphenol A