Endocrine disruptor
[5][6] Found in many household and industrial products, endocrine disruptors "interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body that are responsible for development, behavior, fertility, and maintenance of homeostasis (normal cell metabolism).
Some are persistent organic pollutants (POPs), and can be transported long distances across national boundaries and have been found in virtually all regions of the world, and may even concentrate near the North Pole, due to weather patterns and cold conditions.
[29] One example of the consequences of the exposure of developing animals, including humans, to hormonally active agents is the case of the drug diethylstilbestrol (DES), a nonsteroidal estrogen and not an environmental pollutant.
Depending on the stage of reproductive development, interference with hormonal signaling can result in irreversible effects not seen in adults exposed to the same dose for the same length of time.
[39][40][41] Experiments with animals have identified critical developmental time points in utero and days after birth when exposure to chemicals that interfere with or mimic hormones have adverse effects that persist into adulthood.
[51] Some in the scientific community are concerned that exposure to endocrine disruptors in the womb or early in life may be associated with neurodevelopmental disorders including reduced IQ, ADHD, and autism.
In a 2005 publication, phthalates in pregnant women's urine was linked to subtle, but specific, genital changes in their male infants—a shorter, more female-like anogenital distance and associated incomplete descent of testes and a smaller scrotum and penis.
[66] A consensus statement by the Learning and Developmental Disabilities Initiative argued that "The very low-dose effects of endocrine disruptors cannot be predicted from high-dose studies, which contradicts the standard 'dose makes the poison' rule of toxicology.
Chemicals commonly detected in people include DDT, polychlorinated biphenyls (PCBs), bisphenol A (BPA), polybrominated diphenyl ethers (PBDEs), and a variety of phthalates.
[93] 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".
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.
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."
[124] It became used worldwide to increase monoculture crop yields that were threatened by pest infestation, and to reduce the spread of malaria which had a high mortality rate in many parts of the world.
Its use for agricultural purposes has since been prohibited by national legislation of most countries, while its use as a control against malaria vectors is permitted, as specifically stated by the Stockholm Convention on Persistent Organic Pollutants.
[127] 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.
[147] 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.
[149] 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.
[154] PBDEs have the potential to disrupt thyroid hormone balance and contribute to a variety of neurological and developmental deficits, including low intelligence and learning disabilities.
[53][161][162] Although an expert panel has concluded that there is "insufficient evidence" that they can harm the reproductive system of infants,[163] California,[164][165] Washington state,[166] and Europe have banned them from toys.
[169] 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.
[171] PFOA delivered to pregnant rats produced male offspring with decreased levels of 3-β and 17-β-hydroxysteroid dehydrogenase,[171] a gene that transcribes for proteins involved in the production of sperm.
[173] 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.
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.
[177][178] It has been discussed that the long-term slow decline in average body temperature observed since the beginning of the industrial revolution[179] may result from disrupted thyroid hormone signalling.
[180] Endocrine disruptors affect complex metabolic, reproductive, and neuroendocrine systems, they cannot be modeled in in vitro cell based assay and therefore are important to study in order to understand their risk on humans and wildlife.
These inbred mice have recombinant genomes that are developed to ensure every strain is equally related, this eradicates population structure and can result in false positives with qualitative trait locus (QTL) mapping.
[214] Based on recommendations from an advisory panel, the agency expanded the screening program to include male hormones, the thyroid system, and effects on fish and other wildlife.
[217] The European Commission had been to set criteria by December 2013 identifying endocrine-disrupting chemicals (EDCs) in thousands of products—including disinfectants, pesticides and toiletries—that have been linked to cancers, birth defects and development disorders in children.
We have scientific reports on how this affects fertility of young boys and girls, and other serious effects," Swedish Environment Minister Lena Ek told the AFP, noting that Denmark had also demanded action.
It concluded that EDCs likely cost health systems across the EU anywhere from 59 million to 1.18 billion Euros a year, noting that even this represented only "a fraction of the endocrine related diseases".
