Learn which chemicals to avoid when trying for a baby
During the past 50 or more years, vast quantities of man-made synthetic chemicals have been released into the environment as a consequence of efforts to increase agricultural productivity and as a result of modern manufacturing processes. Exposure to these man-made chemicals can interfere with the normal regulation of the endocrine system; the hormonal system in our bodies including reproductive, which can hinder couples to become pregnant.
The group of known endocrine disruptors are extremely numerous in their variety. It includes numerous synthetic substances used as industrial lubricants and solvents and their by-products: polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs - flame-retardant chemicals) and dioxins such as p-dioxin (TCDD-a by-product of incomplete combustion); plastics: bisphenol A (BPA) and bisphenol S (BPS); plasticizers (phthalates-polyvinyl chloride plastics, which are used to make products such as plastic packaging film and sheets, garden hoses, inflatable toys, blood-storage containers, medical tubing and some children's toys), pesticides: atrazine, cypermethrin, dichlorodiphenyl- trichloroethane (DDT), dieldrin, methoxychlor (MXC) and vinclozolin (VCZ); and drugs: diethylstilbestrol (DES) and ethinyl estradiol (EE), as well as non-steroidal anti-inflammatory drugs (NSAID) and acetaminophen.
PBDEs have been shown to affect male sperm quality. Flame retardant chemicals such as organophosphate (OP) compounds, (TDCPP and TPP) have replaced PBDEs in recent years. However, OP compounds have been found in house dust, which is then digested by the occupants causing an increase in prolactin levels leading to an irregular menstrual cycle and a decrease in semen quality.
Alkylphenol ethoxylates (APEs) are non- ionic surfactants that are used as detergents, emulsifiers and wetting agents. APEs have widespread use in paints, household products, toiletries, pesticides and many other industrial and agricultural products. Excessive exposure to APEs has been shown to affect male reproductive development.
Glycol ethers are used as solvents and as an ingredient in cleaning compounds, liquid soaps and cosmetics. Studies have shown testicular damage, reduced fertility, maternal toxicity, early foetal death, birth defects and delayed development from inhalation and oral exposure to the glycol ethers.
Natural chemicals such as genistein (soybeans) and heavy metals can also have endocrine-disruptive effects. Although there is chronic exposure to endocrine disruptors through inhalation and skin contact, the major route of human exposure is ingestion of food (e.g. meat, fish, dairy products and vegetables), as well as plain water and other beverages.
In recent years, polyfluorinated chemicals (PFCs) have increasingly been investigated for their potential harm to humans. PFCs are also known as perfluorinated chemicals, perfluorochemicals, perfluoroalkyls, perfluorinated alkyl acids, polyfluorinated chemicals, polyfluorinated compounds and polyfluoroalkyl substances.
PFCs are a large group of manufactured compounds that are widely used to make everyday products more resistant to stains, grease and water. For example, PFCs may be used to keep food from sticking to cookware, to make sofas and carpets resistant to stains, to make clothes and mattresses more waterproof and may also be used in some food packaging (fast food containers, microwave popcorn bags), as well as in some firefighting materials.
The most well-known PFCs are perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and their derivatives belonging to the group of perfluoroalkylated substances. The PFCs are very persistent in the environment and some of them have been discovered as global pollutants of air, water, soil and wildlife. Bioaccumulation occurs also in humans and everybody in our society has traces of these PFCs in their blood and internal organs such as the liver, kidneys, spleen, gall bladder and testes. Some of these PFCs, such as PFOS and PFOA, are potential developmental toxicants and are suspected endocrine disruptors with effects on sex hormone levels resulting in lower testosterone levels and higher levels of oestradiol. Other PFCs have estrogenic effects in cell cultures. The industrial production of PFOS and its derivatives stopped in 2000. Most westernised countries have now banned there use.
PFOA is in products designed to repel soil, grease and water, including carpet and furniture treatments, food wraps, sprays for leather, shoes and other clothing, paints and cleaning products and from products like shampoo and floor wax, where PFCs are used as surfactants. The major human exposure to PFCs is most likely from surfactants used for impregnation of consumer goods, such as textiles, foot wear, furniture and carpets, which then releases PFCs to the indoor air and contaminate indoor dust, which is then inhaled by people. Babies and toddlers may be more exposed to house dust whilst playing on the floor and will then collect these contaminated dusts on their fingers and put them in their mouth and digest them. Relative to body weight children have a 5-10 times larger intake of indoor PFCs than adults.
Two recent studies suggest that PFCs may reduce human fertility. In Danish women, higher PFOS and PFOA levels were associated with a longer time to pregnancy and irregular menstrual cycles. Young Danish men with high combined PFOS and PFOA levels also had half the number of normal sperm compared to men with lower levels. This mechanism of this lower sperm count could be polyfluorinated substances effects on interstitial cells (Leydig cells). Leydig cell are commonly enlarged (hyperplasia) amongst infertile men, leading to lower testosterone levels and high oestrogen levels. Exposure to other chemicals such as phthalates can also cause this.
International awareness and concern is increasing. In 2000 the main producer, the 3M Company, voluntarily stopped the production of one of the chemicals (PFOS) and a ban of some fluorotelomers has been introduced in Canada in 2006. In Europe, PFOS and its derivatives were banned in 2008, whilst in the USA they were banned in 2000. However, in China, PFOS levels have increased exponentially since 2003. Levels of PFOS in Shenyang, China in 2004 were approximately seven times higher than those found in the US general population at that time. PFOS are only a small part of the problem. The family of PFCs consists of several hundred other unrestricted chemicals.
Research has shown that some man-made chemicals can bind to androgen and oestrogen receptors in the body, thyroid hormone receptors, to androgen-binding protein and to sex hormone-binding globulin (SHBG). Synthetic chemicals such as pesticides (kills living things), herbicides (weed killer), insecticides (insect killer), polychlorinated biphenyls (PCBs), plasticizers (phthalates) and surfactant breakdown products are known to have an estrogenic effect upon our bodies.
In addition to the compounds discussed above, over 40 other chemicals that are widely distributed in the environment have been reported to have effects on reproduction or to have other endocrine-disrupting effects. However, this number must be considered incomplete, since literally thousands of the man-made chemicals in the environment and most of the phytocompounds have yet to be evaluated for their endocrine-disrupting effects or for their effects on the development and function of reproductive systems.
Although environmental chemicals have weak hormonal activity, they have the ability to interact with more than one steroid. A given toxicant may be present in low concentration in the environment and therefore, is harmless to humans. However, we are not exposed to one toxicant at a time, but rather, to all of the xenobiotics present in our environment. Therefore, numerous potential man-made chemicals work together to be hazardous to human reproductive health.
Other environmental pollutants include those from the burning of wood and secondary cigarette smoke. Research has shown that breathing in second hand cigarette smoke before conceiving can affect the baby's brain. The burning of wood releases a number of pollutants including polychlorinated dibenzodiozins and dibenzofurans, polychlorinated biphenyls, hexachlorobenzene, particulate matter and PAHs. Research has shown that women with long-term exposure to smoke from either cigarettes or the burning of wood in their homes are more likely to have lower levels of AMH and reduced fertility.
Man-made chemicals are commonly used in consumer products too. Unlike soaps or shampoos, which are rinsed off, other cosmetics remain on the body for considerably longer. These man-made chemicals such as parabens (in most makeup, moisturizers, hair care products and shaving products), antiperspirant aluminium salts, cyclosiloxanes (silicones, in combination or alone in personal care products and as carriers, lubricants and solvents), triclosan (found in clothing, kitchenware, furniture, toys, antibacterial soaps and body washes, toothpastes and some cosmetics), ultraviolet (uv) screens and phthalates have an estrogenic potency and react like oestrogens. Phthalates and parabens are found in nail polish, cosmetics, lotions and in perfumes. Phthalates can pass the placenta and can potentially affect the developing foetus.
Phytoestrogens are also added to cosmetics in the form of anthraquinones present in aloe vera and in breast-enhancing creams in the form of 8-prenylnaringenin ('push-up') and miroestrol/deoxymiroestrol (pueraria creams). Many of these compounds are not readily metabolized and due to their lipophilic properties they can accumulate over time in fatty tissues of the body. They can then be released and in conjunction will all the other oestrogen type chemicals cause hormonal imbalances, infertility, PCOS and oestrogen type cancers.