Endocrine System
Image source: EPA.gov (6)
How do EDCs affect the endocrine system?
As previously stated, EDCs stand for Endocrine Disrupting Chemicals, which mean they interfere with the processes of the endocrine system, pictured on the left. Multiple different types of EDCs exist, with various biological mechanisms and functions. However, EDCs have one generally similar way of entering the body, disrupting normal bodily functions, and interfering with hormone synthesis and the reproductive system. EDCs bind to molecules called steroid receptors like the oestrogen receptor, androgen receptor, or progesterone receptor (5). Chemicals have different structures, and EDCs posses what is knows as a phenolic structure. This structure allows them to act as endogenous hormones, which means they can interact with steroid hormone receptors as antagonists (5). Acting as antagonist means they work against the steroid hormone, stopping the action of these hormones. EDCs can also target the estrogen receptor pathway by disrupting communication between endocrine receptors and other nuclear receptors (5). This affects transcriptional activity and can affect the transcription of genes in genomic or non genomic pathways.
Commonly Found EDCs
Although there are numerous forms of EDCs found in the environment, products, food, and manufactured items, here are 3 examples of common EDCs relevant to women's reproductive health, pregnancy, and child development.
Phthalates
Phthalates are a group of EDCs used to make plastic more durable, soft, and flexible. Humans are exposed to phthalates mainly through ingestion of food in contact with plastic film and packaging. There are also phthalates found in personal care products, toys, household products, and cleaning supplies. Phthalate metabolism begins at the gastrointestinal tract, and they commonly alter the creation and metabolism of thyroid hormones (2). Concentrations of phthalate metabolites have been found in amniotic fluid which surround the baby in the womb, suggesting the crossing of phthalates across the placental barrier during pregnancy (2).
Bisphenol A (BPA)
The most common form of BPA exposure is through ingestion via plastic food containers and packaging. BPA is also present in contaminated air, children toys, mechanical parts, technological items and more (2). Products using BPA are widespread and still manufactured in an upward trend (1). BPA has been detected in placental blood, demonstrating how BPA may impact fetal development through epigenetic modifications which are changes to DNA without changing the sequence, increasing risk for neonates and young children (2).
Parabens
Parabens are present in small amounts as preservatives in items such as cosmetics, food, beverages, and pharmaceuticals (3). For personal care products like makeup, moisturizers, or hair products, parabens enter the body through skin absorption (3). Since parabens exist in personal care products, a large part of the affected population include women, with black communities having a disproportionately higher impact due to higher use of hair products.
Cocktail Effect
A majority of EDC research isolates one particular EDC or one category of EDCs for ease of experimentation and the intent of exploring effects of particular EDCs. However, EDCs interact with each other and environmental exposures constitute numerous different EDCs at the same time (4). The cocktail effect describes the combined effects of EDCs and its biological complexity. Combinations of EDCs can produce a significant effect, even when each chemical is present at low doses which may not produce effects individually (4). Since it is invalid to assume that humans are only exposed to one EDC at a time in the environment when these chemicals are ubiquitous in daily life, future research examining the effects of mixtures of EDCs is extremely important and necessary.
