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56-1100: Because of their toxicity and persistence, all commercially relevant PBDEs have been marked for elimination under the Stockholm Convention , a treaty to control and phase out major persistent organic pollutants (POPs). The family of PBDEs consists of 209 possible substances, which are called congeners (PBDE = C 12 H (10− x ) Br x O ( x = 1, 2, ..., 10 = m + n )). The number of isomers for mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, and decabromodiphenyl ethers are 3, 12, 24, 42, 46, 42, 24, 12, 3 and 1, respectively. Lower-brominated PBDEs with 1–4 bromine atoms per molecule are regarded as more dangerous because they more efficiently bioaccumulate . They have been known to affect thyroid hormone levels, and studies have linked them to reproductive and neurological risks at certain concentrations or higher. Higher-brominated PBDEs are less acutely dangerous but biotically and photochemically debrominate to lower-brominated congeners. PBDEs were produced commercially via

112-720: A molecular level estrogen induces the above-mentioned effects on cell via acting on intracellular receptors termed ER α and ER β, which upon ligation form either homo or heterodimers. The genetic and nongenetic targets of the receptors differ between homo and heterodimers. Ligation of these receptors allows them to translocate to the nucleus and act as transcription factors either by binding estrogen response elements (ERE) on DNA or binding DNA together with other transcriptional factors e.g. Nf-kB or AP-1 , both of which result in RNA polymerase recruitment and further chromatin remodelation . A non-transcriptional response to oestrogen stimulation

168-481: A role in suppressing binge eating . Hormone replacement therapy using estrogen may be a possible treatment for binge eating behaviors in females. Estrogen replacement has been shown to suppress binge eating behaviors in female mice. The mechanism by which estrogen replacement inhibits binge-like eating involves the replacement of serotonin (5-HT) neurons. Women exhibiting binge eating behaviors are found to have increased brain uptake of neuron 5-HT, and therefore less of

224-567: Is also growing concern that PBDEs share the environmental long life and bioaccumulation properties of polychlorinated dibenzodioxins . "With the exception of one small case-control study reporting possible associations between adipose PBDE concentrations and risk of pancreatic cancer, there is no evidence for carcinogenicity of PBDEs in human studies." PBDEs have been shown to have hormone-disrupting effects, in particular, on estrogen and thyroid hormones and can interfere with both metabolic and oncogenic pathways. A 2009 animal study conducted by

280-765: Is associated with decreased estradiol and increased progesterone. Klump et al. Progesterone may moderate the effects of low estradiol (such as during dysregulated eating behavior), but that this may only be true in women who have had clinically diagnosed binge episodes (BEs). Dysregulated eating is more strongly associated with such ovarian hormones in women with BEs than in women without BEs. The implantation of 17β-estradiol pellets in ovariectomized mice significantly reduced binge eating behaviors and injections of GLP-1 in ovariectomized mice decreased binge-eating behaviors. The associations between binge eating, menstrual-cycle phase and ovarian hormones correlated. In rodents, estrogens (which are locally aromatized from androgens in

336-527: Is banned in Europe for this use and in some U.S. states. For PBDE, EPA has set reference dose of 7 micrograms per kilogram of body weight, which is "believed to be without appreciable effects". However, Linda Birnbaum , PhD, a senior toxicologist formerly with the EPA (now at NIEHS) notes concern: "What I see is another piece of evidence that supports the fact that levels of these chemicals in children appear to be higher than

392-459: Is critical in mediating breast development during puberty , as well as breast maturation during pregnancy in preparation of lactation and breastfeeding . Estrogen is primarily and directly responsible for inducing the ductal component of breast development, as well as for causing fat deposition and connective tissue growth. It is also indirectly involved in the lobuloalveolar component, by increasing progesterone receptor expression in

448-488: Is different. These tissues are not able to synthesize C19 steroids, and therefore depend on C19 supplies from other tissues and the level of aromatase. In females, synthesis of estrogens starts in theca interna cells in the ovary, by the synthesis of androstenedione from cholesterol . Androstenedione is a substance of weak androgenic activity which serves predominantly as a precursor for more potent androgens such as testosterone as well as estrogen. This compound crosses

504-623: Is estimated to have been 175   kt for pentaBDE, 130   kt for octaBDE, and 1600   kt for decaBDE. Since the 1990s, environmental concerns were raised because of the high hydrophobicity of PBDEs and their high resistance to degradation processes. In 1995 for example, it was found that Buffalo River fish ( common carp ) were contaminated with this compound and the tissue concentrations were ranged from 13.1–22.8 ng/g wet wt. People are exposed to low levels of PBDEs through ingestion of food and by inhalation. PBDEs bioaccumulate in blood, breast milk, and fat tissues. Personnel associated with

560-528: Is expressed in specific tissues including the ovary, uterus and breast. The metabolic effects of estrogen in postmenopausal women have been linked to the genetic polymorphism of the ER. While estrogens are present in both men and women , they are usually present at significantly higher levels in women of reproductive age. They promote the development of female secondary sexual characteristics , such as breasts , darkening and enlargement of nipples , and thickening of

616-547: Is in line with its Th2 bias. Activity of basophils , eosinophils , M2 macrophages and is enhanced, whereas activity of NK cells is downregulated. Conventional dendritic cells are biased towards Th2 under the influence of estrogen, whereas plasmacytoid dendritic cells, key players in antiviral defence, have increased IFN-g secretion. Estrogen also influences B cells by increasing their survival, proliferation, differentiation and function, which corresponds with higher antibody and B cell count generally detected in women. On

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672-496: Is not uniformly favorable and is dependent on the timing of the dose and the type of cognitive skill being measured. The protective effects of estrogens on cognition may be mediated by estrogen's anti-inflammatory effects in the brain. Studies have also shown that the Met allele gene and level of estrogen mediates the efficiency of prefrontal cortex dependent working memory tasks. Researchers have urged for further research to illuminate

728-733: Is the case of the effect of male sex hormone - testosterone. Indeed, women respond better to vaccines , infections and are generally less likely to develop cancer , the tradeoff of this is that they are more likely to develop an autoimmune disease . The Th2 shift manifests itself in a decrease of cellular immunity and increase in humoral immunity ( antibody production) shifts it from cellular to humoral by downregulating cell-mediated immunity and enhancing Th2 immune response by stimulating IL-4 production and Th2 differentiation. Type 1 and type 17 immune responses are downregulated, likely to be at least partially due to IL-4 , which inhibits Th1. Effect of estrogen on different immune cells' cell types

784-476: Is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy. Estrogens are synthesized in all vertebrates and some insects. Quantitatively, estrogens circulate at lower levels than androgens in both men and women. While estrogen levels are significantly lower in males than in females, estrogens nevertheless have important physiological roles in males. Like all steroid hormones , estrogens readily diffuse across

840-508: Is the predominant circulating estrogen and during pregnancy estriol is the predominant circulating estrogen in terms of serum levels. Given by subcutaneous injection in mice, estradiol is about 10-fold more potent than estrone and about 100-fold more potent than estriol. Thus, estradiol is the most important estrogen in non-pregnant females who are between the menarche and menopause stages of life. However, during pregnancy this role shifts to estriol, and in postmenopausal women estrone becomes

896-415: Is typically triggered by low estrogen levels, and is often mistaken for premenstrual dysphoric disorder . Compulsions in male lab mice, such as those in obsessive-compulsive disorder (OCD), may be caused by low estrogen levels. When estrogen levels were raised through the increased activity of the enzyme aromatase in male lab mice, OCD rituals were dramatically decreased. Hypothalamic protein levels in

952-669: The basal membrane into the surrounding granulosa cells, where it is converted either immediately into estrone, or into testosterone and then estradiol in an additional step. The conversion of androstenedione to testosterone is catalyzed by 17β-hydroxysteroid dehydrogenase (17β-HSD), whereas the conversion of androstenedione and testosterone into estrone and estradiol, respectively is catalyzed by aromatase, enzymes which are both expressed in granulosa cells. In contrast, granulosa cells lack 17α-hydroxylase and 17,20-lyase , whereas theca cells express these enzymes and 17β-HSD but lack aromatase. Hence, both granulosa and theca cells are essential for

1008-457: The brain have neuroprotective effects. Estrogen regulates the transcription of DNA base excision repair genes as well as the translocation of the base excision repair enzymes between different subcellular compartments. Estrogens are involved in libido (sex drive) in both women and men. Verbal memory scores are frequently used as one measure of higher level cognition . These scores vary in direct proportion to estrogen levels throughout

1064-607: The bromination of diphenyl ether , with three technical-grade mixtures being sold, varying by degree of bromination. In the United States, PBDEs were marketed with the trade names DE-60F, DE-61, DE-62, and DE-71 applied to pentaBDE mixtures, DE-79 applied to octaBDE mixtures, and DE 83R and Saytex 102E applied to decaBDE mixtures. The available commercial PBDE products were not single compounds or even single congeners but rather mixtures of congeners. Technical pentaBDE predominantly contained pentabromo derivatives (50–62%); however,

1120-481: The catechol estrogens 2-hydroxyestradiol , 2-hydroxyestrone , 4-hydroxyestradiol , and 4-hydroxyestrone , as well as 16α-hydroxyestrone , are also estrogens with varying degrees of activity. The biological importance of these minor estrogens is not entirely clear. The actions of estrogen are mediated by the estrogen receptor (ER), a dimeric nuclear protein that binds to DNA and controls gene expression . Like other steroid hormones, estrogen enters passively into

1176-592: The cell membrane . Once inside the cell, they bind to and activate estrogen receptors (ERs) which in turn modulate the expression of many genes . Additionally, estrogens bind to and activate rapid-signaling membrane estrogen receptors (mERs), such as GPER (GPR30). In addition to their role as natural hormones, estrogens are used as medications , for instance in menopausal hormone therapy , hormonal birth control and feminizing hormone therapy for transgender women , intersex people, and nonbinary people . Synthetic and natural estrogens have been found in

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1232-669: The endometrium and other aspects of regulating the menstrual cycle. In males, estrogen regulates certain functions of the reproductive system important to the maturation of sperm and may be necessary for a healthy libido . Estrogens are responsible for the development of female secondary sexual characteristics during puberty , including breast development , widening of the hips , and female fat distribution . Conversely, androgens are responsible for pubic and body hair growth , as well as acne and axillary odor . Estrogen, in conjunction with growth hormone (GH) and its secretory product insulin-like growth factor 1 (IGF-1),

1288-543: The ovaries , and during pregnancy, the placenta . Follicle-stimulating hormone (FSH) stimulates the ovarian production of estrogens by the granulosa cells of the ovarian follicles and corpora lutea . Some estrogens are also produced in smaller amounts by other tissues such as the liver , pancreas , bone , adrenal glands , skin , brain , adipose tissue , and the breasts . These secondary sources of estrogens are especially important in postmenopausal women. The pathway of estrogen biosynthesis in extragonadal tissues

1344-555: The US Environmental Protection Agency (EPA) demonstrates that deiodination, active transport, sulfation, and glucuronidation may be involved in disruption of thyroid homeostasis after perinatal exposure to PBDEs during critical developmental time points in utero and shortly after birth. The adverse effects on hepatic mechanism of thyroid hormone disruption during development have been shown to persist into adulthood. The EPA noted that PBDEs are particularly toxic to

1400-535: The United States because of health and safety concerns. Based on a comprehensive risk assessment under the Existing Substances Regulation 793/93/EEC, the European Union has completely banned the use of penta- and octaBDE since 2004. However, both chemicals are still found in furniture and foam items made before the phase-out was completed. The most common PBDEs used in electronics are decaBDE. DecaBDE

1456-681: The ages of one and six. Developmental effects were particularly evident at four years of age, when verbal and full IQ scores were reduced 5.5 to 8.0 points for those with the highest prenatal exposures after correcting for sex, ethnicity, tobacco smoke exposure, and mother's IQ. Increasing environmental concentrations and changing distributions of PBDEs in sediments of the Clyde River Estuary in Scotland, UK have been assessed. Analysis of six sediment cores each of 1 m depth from Glasgow city to Greenock revealed that total concentrations increased toward

1512-499: The brain) play an important role in psychosexual differentiation, for example, by masculinizing territorial behavior; the same is not true in humans. In humans, the masculinizing effects of prenatal androgens on behavior (and other tissues, with the possible exception of effects on bone) appear to act exclusively through the androgen receptor. Consequently, the utility of rodent models for studying human psychosexual differentiation has been questioned. Estrogens are responsible for both

1568-718: The breasts and by inducing the secretion of prolactin . Allowed for by estrogen, progesterone and prolactin work together to complete lobuloalveolar development during pregnancy. Androgens such as testosterone powerfully oppose estrogen action in the breasts, such as by reducing estrogen receptor expression in them. Estrogens are responsible for maturation and maintenance of the vagina and uterus , and are also involved in ovarian function, such as maturation of ovarian follicles . In addition, estrogens play an important role in regulation of gonadotropin secretion . For these reasons, estrogens are required for female fertility . Estrogen regulated DNA repair mechanisms in

1624-413: The cell where it binds to and activates the estrogen receptor. The estrogen:ER complex binds to specific DNA sequences called a hormone response element to activate the transcription of target genes (in a study using an estrogen-dependent breast cancer cell line as model, 89 such genes were identified). Since estrogen enters all cells, its actions are dependent on the presence of the ER in the cell. The ER

1680-436: The delicate balance between fighting infections and protecting arteries from damage thus lowering the risk of cardiovascular disease. During pregnancy , high levels of estrogens increase coagulation and the risk of venous thromboembolism . Estrogen has been shown to upregulate the peptide hormone adropin . The effect of estrogen on the immune system is in general described as Th2 favoring, rather than suppressive, as

1736-673: The details below. Request from 172.68.168.226 via cp1108 cp1108, Varnish XID 824920327 Upstream caches: cp1108 int Error: 429, Too Many Requests at Fri, 29 Nov 2024 08:27:52 GMT Estrogen Estrogen (also spelled oestrogen in British English ; see spelling differences ) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics . There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane ,

Polybrominated diphenyl ethers - Misplaced Pages Continue

1792-617: The developing brains of animals. Peer-reviewed studies have shown that even a single dose administered to mice during development of the brain can cause permanent changes in behavior, including hyperactivity. Swedish scientists first reported substances related to pentaBDE were accumulating in human breast milk. Studies by the Swedish Society for Nature Conservation found for the first time very high levels of more highly brominated PBDEs (BDE-209) in eggs of peregrine falcons . Two forms of PBDEs, penta- and octaBDE, are no longer manufactured in

1848-734: The end of 2013 for decaBDE. The European Union decided to ban the use of two classes of flame retardants, in particular, PBDEs and polybrominated biphenyls (PBBs) in electric and electronic devices. This ban was formalised in the RoHS Directive, and an upper limit of 1 g/kg for the sum of PBBs and PBDEs was set. In February 2009, the Institute for Reference Materials and Measurements released two certified reference materials to help analytical laboratories better detect these two classes of flame retardants. The reference materials were custom-made to contain all relevant PBDEs and PBBs at levels close to

1904-530: The environment and are referred to as xenoestrogens . Estrogens are among the wide range of endocrine-disrupting compounds (EDCs) and can cause health issues and reproductive disfunction in both wildlife and humans. The four major naturally occurring estrogens in women are estrone (E1), estradiol (E2), estriol (E3), and estetrol (E4). Estradiol (E2) is the predominant estrogen during reproductive years both in terms of absolute serum levels as well as in terms of estrogenic activity. During menopause , estrone

1960-416: The environment, and, according to the EPA, exposure may pose health risks. According to U.S. EPA's Integrated Risk Information System, evidence indicates that PBDEs may possess liver toxicity, thyroid toxicity, and neurodevelopmental toxicity. In June 2008, the U.S. EPA set a safe daily exposure level ranging from 0.1 to 7 ug per kg body weight per day for the four most common PBDE congeners. In April 2007,

2016-404: The gene COMT are enhanced by increasing estrogen levels which are believed to return mice that displayed OCD rituals to normal activity. Aromatase deficiency is ultimately suspected which is involved in the synthesis of estrogen in humans and has therapeutic implications in humans having obsessive-compulsive disorder. Local application of estrogen in the rat hippocampus has been shown to inhibit

2072-538: The legal limit. At an international level, in May 2009 the Parties of the Stockholm Convention on Persistent Organic Pollutants (POPs) decided to list commercial pentaBDE and commercial octaBDE as POP substances. This listing is due to the properties of hexaBDE and heptaBDE, which are components of commercial octaBDE, and to the properties of tetraBDE and pentaBDE, which are the main components of commercial pentaBDE. In 2017, it

2128-415: The legislature of the state of Washington passed a bill banning the use of PBDEs. The State of Maine Department of Environmental Protection found that all PBDEs should be banned. In May 2007, the legislature of the state of Maine passed a bill phasing out the use of decaPBDE. The U.S. importers and manufacturers of PBDEs have now withdrawn them from sale, by the end of 2004 for pentaBDE and octaBDE, and by

2184-613: The levels in their parents; I think this study raises a red flag." A previous study by the Environmental Working Group in 2003 published test results showing that the average level of fire-retardants in breast milk from 20 American mothers was 75 times higher than the average levels measured in Europe. Increasing levels of PBDEs in the environment may be responsible for the increasing incidence of feline hyperthyroidism . A study in 2007 found PBDE levels in cats 20- to 100-fold greater than median levels in U.S. adults, although it

2240-673: The manufacture of PBDE-containing products are exposed to highest levels of PBDEs. Bioaccumulation is of particular concern in such instances, especially for personnel in recycling and repair plants working on PBDE-containing products. People are also exposed to these chemicals in their domestic environment because of their prevalence in common household items. Studies in Canada have found significant concentrations of PBDEs in common foods such as salmon , ground beef , butter , and cheese . A 2024 study found most forms of black plastic household displayed high PBDE concentrations of up to 3% by weight due to

2296-400: The menstrual cycle, pregnancy, and menopause. Furthermore, estrogens when administered shortly after natural or surgical menopause prevents decreases in verbal memory. In contrast, estrogens have little effect on verbal memory if first administered years after menopause. Estrogens also have positive influences on other measures of cognitive function. However the effect of estrogens on cognition

Polybrominated diphenyl ethers - Misplaced Pages Continue

2352-708: The methoxy-PBDEs in the whale had come from artificial (human-made) sources, they would have contained only stable isotopes of carbon because virtually all PBDEs that are produced artificially use petroleum as the source of carbon; all carbon-14 would have long since completely decayed from that source. The isotopic signatures of the PBDEs themselves were not evaluated. The carbon-14 may instead be in methoxy groups enzymatically added to man-made PBDEs. A 2010 study found that children with higher concentrations of PBDE congeners 47, 99 and 100 in their umbilical cord blood at birth scored lower on tests of mental and physical development between

2408-429: The mid- luteal phase . It is hypothesized that these changes occur due to brain changes across the menstrual cycle that are likely a genomic effect of hormones. These effects produce menstrual cycle changes, which result in hormone release leading to behavioral changes, notably binge and emotional eating. These occur especially prominently among women who are genetically vulnerable to binge eating phenotypes. Binge eating

2464-419: The mixture also contained tetrabromides (24–38%) and hexabromides (4–8%), as well as traces of the tribromides (0–1%). Technical octaBDE was a mixture of homologs: hexa-, hepta-, octa-, nona-, and decabromides. Technical decaBDE was 97% decabromide, with small amounts of octa- and nonabromides. Commercial production of PBDEs began in the 1970s, and continued until the early 2010s. Cumulative global production

2520-454: The neurotransmitter serotonin in the cerebrospinal fluid. Estrogen works to activate 5-HT neurons, leading to suppression of binge like eating behaviors. It is also suggested that there is an interaction between hormone levels and eating at different points in the female menstrual cycle . Research has predicted increased emotional eating during hormonal flux, which is characterized by high progesterone and estradiol levels that occur during

2576-639: The primary form of estrogen in the body. Another type of estrogen called estetrol (E4) is produced only during pregnancy. All of the different forms of estrogen are synthesized from androgens , specifically testosterone and androstenedione , by the enzyme aromatase . Minor endogenous estrogens, the biosyntheses of which do not involve aromatase , include 27-hydroxycholesterol , dehydroepiandrosterone (DHEA), 7-oxo-DHEA , 7α-hydroxy-DHEA , 16α-hydroxy-DHEA , 7β-hydroxyepiandrosterone , androstenedione (A4), androstenediol (A5), 3α-androstanediol , and 3β-androstanediol . Some estrogen metabolites, such as

2632-705: The production of estrogen in the ovaries. Estrogen levels vary through the menstrual cycle , with levels highest near the end of the follicular phase just before ovulation . Note that in males, estrogen is also produced by the Sertoli cells when FSH binds to their FSH receptors. Estrogens are plasma protein bound to albumin and/or sex hormone-binding globulin in the circulation. Estrogens are metabolized via hydroxylation by cytochrome P450 enzymes such as CYP1A1 and CYP3A4 and via conjugation by estrogen sulfotransferases ( sulfation ) and UDP-glucuronyltransferases ( glucuronidation ). In addition, estradiol

2688-527: The pubertal growth spurt, which causes an acceleration in linear growth, and epiphyseal closure , which limits height and limb length, in both females and males. In addition, estrogens are responsible for bone maturation and maintenance of bone mineral density throughout life. Due to hypoestrogenism, the risk of osteoporosis increases during menopause . Women are less impacted by heart disease due to vasculo-protective action of estrogen which helps in preventing atherosclerosis. It also helps in maintaining

2744-514: The re-uptake of serotonin . Contrarily, local application of estrogen has been shown to block the ability of fluvoxamine to slow serotonin clearance, suggesting that the same pathways which are involved in SSRI efficacy may also be affected by components of local estrogen signaling pathways. Studies have also found that fathers had lower levels of cortisol and testosterone but higher levels of estrogen (estradiol) than did non-fathers. Estrogen may play

2800-412: The river bed surface (0–10 cm). Amounts of PBDE ranged from 1 to 2,645 µg/kg (dry wt. sediment) with a mean of 287 µg/kg (dry wt. sediment). Down-core PBDE congener profiles showed that higher concentrations were due to elevated levels of BDE-209. The majority of the sediment records clearly showed a change from mainly lower molecular weight BDEs 47,99, 183, 153 at lower depths to BDE-209 near

2856-535: The role of estrogen and its potential for improvement on cognitive function. Estrogen is considered to play a significant role in women's mental health . Sudden estrogen withdrawal, fluctuating estrogen, and periods of sustained low estrogen levels correlate with a significant lowering of mood. Clinical recovery from postpartum , perimenopause , and postmenopause depression has been shown to be effective after levels of estrogen were stabilized and/or restored. Menstrual exacerbation (including menstrual psychosis)

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2912-537: The surface, a change in congener and homologue group patterns that corresponds to the restrictions of penta- and octaBDE commercial mixtures under EU law in 2004–2006. While biodegradation is not considered the main pathway for PBDEs, photolysis and pyrolysis can be of interest in studies of transformation of PBDEs. In August, 2003, the State of California outlawed the sale of penta- and octaBDE and products containing them, effective January 1, 2008. PBDEs are ubiquitous in

2968-425: The use of recycled E-waste in the production process. Black plastic spatulas and other cooking implements exposed to high temperatures would be especially likely to leach the material into food. PBDEs have also been found at high levels in indoor dust, sewage sludge, and effluents from wastewater treatment plants. Increasing PBDE levels have been detected in the blood of marine mammals such as harbor seals . There

3024-702: Was also documented (termed membrane-initiated steroid signalling, MISS). This pathway stimulates the ERK and PI3K/AKT pathways, which are known to increase cellular proliferation and affect chromatin remodelation. Researchers have implicated estrogens in various estrogen-dependent conditions , such as ER-positive breast cancer , as well as a number of genetic conditions involving estrogen signaling or metabolism, such as estrogen insensitivity syndrome , aromatase deficiency , and aromatase excess syndrome . High estrogen can amplify stress-hormone responses in stressful situations. Estrogens, in females, are produced primarily by

3080-496: Was decided to also list decaBDE. Major decaBDE producers have switched to manufacturing decabromodiphenyl ethane , a structurally related compound that has also come under suspicion as an environmental pollutant. Non-halogenated alternatives also exist. Stockholm Convention on Persistent Organic Pollutants Too Many Requests If you report this error to the Wikimedia System Administrators, please include

3136-452: Was not adequately powered to establish an association between hyperthyroid cats and serum PBDE levels. Subsequent studies have indeed found such an association. An experiment conducted at Woods Hole Oceanographic Institution in 2005 showed that the isotopic signature of methoxy-PBDEs found in whale blubber contained carbon-14 , the naturally occurring radioactive isotope of carbon. Methoxy-PBDEs are produced by some marine species. If

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