All people are exposed to chemicals with estrogenic effects in their everyday life, because endocrine disrupting chemicals are found in low doses in thousands of products. Chemicals commonly detected in people include
DDT,
polychlorinated biphenyls (PCBs),
bisphenol A (BPA),
polybrominated diphenyl ethers (PBDEs), and a variety of
phthalates. In fact, almost all plastic products, including those advertised as BPA-free, have been found to leach endocrine-disrupting chemicals. In a 2011, study it was found that some BPA-free products released more endocrine-active chemicals than the BPA-containing products. Other forms of endocrine disruptors are
phytoestrogens, compounds with estrogen activity found in plants.
Xenoestrogens Xenoestrogens are a type of
xenohormone that imitates
estrogen. Synthetic xenoestrogens include widely used industrial compounds, such as
PCBs,
BPA and
phthalates, which have estrogenic effects on a living organism.
Alkylphenols Alkylphenols are
xenoestrogens. The European Union has implemented sales and use restrictions on certain applications in which
nonylphenols are used because of their alleged "toxicity, persistence, and the liability to bioaccumulate" but the
United States Environmental Protections Agency (EPA) has taken a slower approach to make sure that action is based on "sound science". The long-chain alkylphenols are used extensively as precursors to the
detergents, as additives for fuels and
lubricants, polymers, and as components in
phenolic resins. These compounds are also used as building block chemicals that are also used in making
fragrances, thermoplastic
elastomers,
antioxidants, oil field chemicals and
fire retardant materials. Through the downstream use in making alkylphenolic resins, alkylphenols are also found in tires, adhesives, coatings, carbonless copy paper and high performance rubber products. They have been used in industry for over 40 years. Certain alkylphenols are degradation products from nonionic
detergents. Nonylphenol is considered to be a low-level endocrine disruptor owing to its tendency to mimic estrogen.
Bisphenol A (BPA) Bisphenol A is commonly found in plastic bottles, plastic food containers, dental materials, and the linings of metal
food and infant formula cans. Another exposure comes from receipt paper commonly used at grocery stores and restaurants, because today the paper is commonly coated with a BPA containing clay for printing purposes. BPA is a known endocrine disruptor, and numerous studies have found that laboratory animals exposed to low levels of it have elevated rates of
diabetes,
mammary and
prostate cancers, decreased sperm count, reproductive problems, early
puberty,
obesity, and neurological problems. Studies in the US have shown that healthy women without any fertility problems found that urinary BPA was unrelated to time of pregnancy despite a shorter luteal phase (second part of the menstrual cycle) being reported. Additional studies have been conducted in fertility centers say that BPA exposure is correlation with lower ovarian reserves. To combat this, most women will undergo IVF to help with the poor ovarian stimulation response; seemingly all of them have elevated levels of BPA in the urinary tract. Median conjugation of BPA concentrations were higher in those who did have a miscarriage compared to those who had a live birth. All of these studies show that BPA can have an effect on ovarian functions and the pivotal early part of conception. One study did show racial or ethnic differences as Asian women were found to have an increased
oocyte maturity rate, but all of the women had significantly lower concentration of BPA in the study. Early developmental stages appear to be the period of greatest sensitivity to its effects, and some studies have linked prenatal exposure to later physical and neurological difficulties. Regulatory bodies have determined safety levels for humans, but those safety levels are currently being questioned or are under review as a result of new scientific studies. A 2011
cross-sectional study that investigated the number of chemicals pregnant women are exposed to in the U.S. found BPA in 96% of women. In 2010 the
World Health Organization expert panel recommended no new regulations limiting or banning the use of bisphenol A, stating that "initiation of public health measures would be premature." In August 2008, the U.S. FDA issued a draft reassessment, reconfirming their initial opinion that, based on scientific evidence, BPA is safe. However, in October 2008, FDA's advisory Science Board concluded that the Agency's assessment was "flawed" and had not proven the chemical to be safe for formula-fed infants. In January 2010, the FDA issued a report indicating that, due to findings of recent studies that used novel approaches in testing for subtle effects, both the National Toxicology Program at the National Institutes of Health as well as the FDA have some level of concern regarding the possible effects of BPA on the brain and behavior of fetuses, infants and younger children. In 2012 the FDA did ban the use of BPA in baby bottles; however, the
Environmental Working Group called the ban "purely cosmetic". In a statement they said, "If the agency truly wants to prevent people from being exposed to this toxic chemical associated with a variety of serious and chronic conditions it should ban its use in cans of infant formula, food and beverages." The
Natural Resources Defense Council called the move inadequate saying, the FDA needs to ban BPA from all
food packaging. In a statement a FDA spokesman said the agency's action was not based on safety concerns and that "the agency continues to support the safety of BPA for use in products that hold food." A program initiated by
NIEHS,
NTP, and the U.S.
Food and Drug Administration (named CLARITY-BPA) found no effect of chronic exposure to BPA on rats and the FDA considers currently authorized uses of BPA to be safe for consumers. The
Environmental Protection Agency set a reference dose for BPA at 50 μg/kg/day for mammals, although exposure to doses lower than the reference dose has been shown to affect both male and female reproductive systems.
Bisphenol S (BPS) and bisphenol F (BPF) Bisphenol S and Bisphenol F are analogs of bisphenol A. They are commonly found in thermal receipts, plastics, and household dust. Traces of BPS have also been found in personal care products. It is more presently being used because of the ban of BPA. BPS is used in place of BPA in BPA-free items. However, BPS and BPF have been shown to be endocrine disruptors as much as BPA.
DDT Dichlorodiphenyltrichloroethane (DDT) was first used as a pesticide against
Colorado potato beetles on crops beginning in 1936. An increase in the incidence of
malaria, epidemic
typhus,
dysentery, and
typhoid fever led to its use against the mosquitoes, lice, and houseflies that carried these diseases. Before World War II,
pyrethrum, an extract of a flower from Japan, had been used to control these insects and the diseases they can spread. During World War II, Japan stopped exporting pyrethrum, forcing the search for an alternative. Fearing an epidemic outbreak of typhus, every British and American soldier was issued DDT, who used it to routinely dust beds, tents, and barracks all over the world. DDT was approved for general, non-military use after the war ended. As early as 1946, the harmful effects of DDT on birds, beneficial insects, fish, and marine invertebrates were seen in the environment. The most infamous example of these effects were seen in the eggshells of large predatory birds, which did not develop to be thick enough to support the adult bird sitting on them. Further studies found DDT in high concentrations in carnivores all over the world, the result of
biomagnification through the
food chain. Twenty years after its widespread use, DDT was found trapped in ice samples taken from Antarctic snow, suggesting wind and water are another means of environmental transport. Recent studies show the historical record of DDT deposition on remote glaciers in the Himalayas. More than sixty years ago when biologists began to study the effects of DDT on laboratory animals, it was discovered that DDT interfered with reproductive development. Recent studies suggest DDT may inhibit the proper development of female reproductive organs that adversely affects reproduction into maturity. Additional studies suggest that a marked decrease in fertility in adult males may be due to DDT exposure. Most recently, it has been suggested that exposure to DDT in utero can increase a child's risk of
childhood obesity. DDT is still used as anti-malarial insecticide in Africa and parts of Southeast Asia in limited quantities.
Polychlorinated biphenyls Polychlorinated biphenyls (PCBs) are a class of chlorinated compounds used as industrial coolants and lubricants. PCBs are created by heating benzene, a byproduct of gasoline refining, with chlorine. They were first manufactured commercially by the Swann Chemical Company in 1927. In 1933, the health effects of direct PCB exposure was seen in those who worked with the chemicals at the manufacturing facility in Alabama. In 1935,
Monsanto acquired the company, taking over US production and licensing PCB manufacturing technology internationally. General Electric was one of the largest US companies to incorporate PCBs into manufactured equipment. The effects of acute exposure to PCBs were well known within the companies who used Monsanto's PCB formulation who saw the effects on their workers who came into contact with it regularly. Direct skin contact results in a severe acne-like condition called
chloracne. Exposure increases the risk of skin cancer, liver cancer, and brain cancer. Monsanto tried for years to downplay the health problems related to PCB exposure in order to continue sales. The detrimental health effects of PCB exposure to humans became undeniable when two separate incidents of contaminated cooking oil
poisoned thousands of residents in Japan (Yushō disease, 1968) and Taiwan (Yu-cheng disease, 1979), leading to a worldwide ban on PCB use in 1977. Recent studies show the endocrine interference of certain PCB congeners is toxic to the liver and thyroid, increases childhood obesity in children exposed prenatally, PCBs in the environment may also be related to reproductive and infertility problems in wildlife. In Alaska, it is thought that they may contribute to reproductive defects, infertility and antler malformation in some deer populations. Declines in the populations of otters and sea lions may also be partially due to their exposure to PCBs, the insecticide DDT, other persistent organic pollutants. Bans and restrictions on the use of EDCs have been associated with a reduction in health problems and the recovery of some wildlife populations.
Polybrominated diphenyl ethers Polybrominated diphenyl ethers (PBDEs) are a class of compounds found in
flame retardants used in plastic cases of televisions and computers, electronics, carpets, lighting, bedding, clothing, car components, foam cushions and other
textiles. Potential health concern: PBDEs are structurally very similar to
polychlorinated biphenyls (PCBs), and have similar
neurotoxic effects. Research has correlated
halogenated hydrocarbons, such as PCBs, with
neurotoxicity. Once
World War II began, the US military used these new plastic materials to improve weapons, protect equipment, and to replace heavy components in aircraft and vehicles. but now home furnishings were composed of mostly synthetic materials. More than 500 billion cigarettes were consumed each year in the 1960s, as compared to less than 3 billion per year in the beginning of the twentieth century. When combined with high-density living, the potential for home fires was higher in the 1960s than it had ever been in the US. By the late 1970s, approximately 6000 people in the US died each year in home fires. In 1972, in response to this situation, the National Commission on Fire Prevention and Control was created to study the fire problem in the US. In 1973 they published their findings in "America Burning", a 192-page report that made recommendations to increase fire prevention. Most of the recommendations dealt with fire prevention education and improved building engineering, such as the installation of fire sprinklers and smoke detectors. The Commission expected that with the recommendations, a 5% reduction in fire losses could be expected each year, halving the annual losses within 14 years. Historically, treatments with alum and borax were used to reduce the
flammability of fabric and wood, as far back as Roman times. Since it is a non-absorbent material once created, flame retardant chemicals are added to plastic during the polymerization reaction when it is formed. Organic compounds based on halogens like bromine and chlorine are used as the flame retardant additive in plastics, and in fabric based textiles as well. In 1992, the world market consumed approximately 150,000 tonnes of bromine-based flame retardants, and GLCC produced 30% of the world supply. Many of the most common PBDE's were banned in the
European Union in 2006. Studies with rodents have suggested that even brief exposure to PBDEs can cause developmental and behavior problems in juvenile rodents and exposure interferes with proper thyroid hormone regulation.
Phthalates Phthalates are found in some soft toys, flooring, medical equipment, cosmetics and air fresheners. They are of potential health concern because they are known to disrupt the endocrine system of animals, and some research has implicated them in the rise of birth defects of the male reproductive system. Although an expert panel has concluded that there is "insufficient evidence" that they can harm the reproductive system of infants, California, Washington state, and Europe have banned them from toys. One phthalate,
bis(2-ethylhexyl) phthalate (DEHP), used in medical tubing, catheters and blood bags, may harm sexual development in male infants. Similarly, phthalates may play a causal role in disrupting masculine neurological development when exposed prenatally.
Dibutyl phthalate (DBP) has also disrupted
insulin and
glucagon signaling in animal models.
Perfluorooctanoic acid PFOA is a stable chemical that has been used for its grease-, fire-, and water-resistant properties in products such as
non-stick pan coatings, furniture, firefighter equipment, industrial, and other common household items. There is evidence to suggest that PFOA is an endocrine disruptor affecting male and female reproductive systems. Adult women have exhibited low progesterone and androstenedione production when exposed to PFOA, leading to menstrual and reproductive health issues. Many sunscreens contain
oxybenzone, a chemical blocker that provides broad-spectrum UV coverage, yet is subject to a lot of controversy due its potential estrogenic effect in humans.
Tributyltin (TBT) are organotin compounds. For 40 years TBT was used as a
biocide in
anti-fouling paint, commonly known as bottom paint. TBT has been shown to impact invertebrate and vertebrate development, disrupting the endocrine system, resulting in masculinization, lower survival rates, as well as many health problems in mammals. ==Temporal trends of body burden==