chemistry

Polybrominated diphenyl ethers

Polybrominated diphenyl ethers is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Polybrominated diphenyl ethers rather than just read about it. In short: Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that have been used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles.

Key takeaways

Polybrominated diphenyl ethers belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Polybrominated diphenyl ethers to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Polybrominated diphenyl ethers from memory before moving on to harder problems.

Reference excerpt

Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that have been used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. They are structurally akin to polychlorinated diphenyl ethers (PCDEs), polychlorinated biphenyls (PCBs) and other polyhalogenated compounds, consisting of two halogenated aromatic rings. PBDEs are classified according to the average number of bromine atoms in the molecule. The life-saving benefits of fire retardants led to their popularization. Standards for mass transit vehicles continues to increase as of 2021. 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).

Classes of PBDEs The family of PBDEs consists of 209 possible substances, which are called congeners (PBDE = C12H(10−x)BrxO (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.

Production PBDEs were produced commercially via 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, 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 is estimated to have been 175 kt for pentaBDE, 130 kt for octaBDE, and 1600 kt for decaBDE.

Health and environmental concerns

Exposure Polybrominated diphenyl ethers (PBDEs) can be released into the environment where they are used or produced, possibly entering air, water, soil or the human digestive system when consumed, inhaled or via the skin. Despite the banning and phase out of several forms of PBDEs, many consumer products still contain them in the 21st century, and represent potential exposure sources, including furniture and other consumer products containing polyurethane foam, appliances, pipes, plastics, and old electronic equipment. Generally, governments have determined that PBDEs are not harmful to human health in the exposure amounts assessed. Ingestion of house dust accounts for 80–90% of total PBDE exposure, while the remaining exposure occurs from food ingestion. PBDE-contaminated foods, particularly those high in fat content, such as fatty meats or fish, are possible sources of exposure. In breastfeeding infants, breast milk may be an exposure source because PBDEs can be present in the mother and her milk. Various other food items may contain PBDEs, including meat, meat products, dairy products, and seafood. PBDEs have not been detected beyond trace levels in water. In the environment, soils and sediments are the major deposits for PBDEs. PBDEs can enter soil from discarded products, such as in landfills. As biosolids (sewage) may contain PBDEs, exposure from soils or farmlands that have been fertilized with biosolids may occur. Wildlife may have exposure by consuming foods containing PBDEs, whereas organisms that live in sediments may be contaminated by PBDEs.

Excretion PBDEs and their metabolites are excreted mainly in the feces and some in the urine. Owing to their deposition in body fat stores, some PBDEs remain in the body for many years, and may enter the bodies of unborn babies via the placenta.

Research on health effects Nothing certain has been established about the effects of PBDEs on human health. Most information regarding toxicity of PBDEs and their metabolites is from early-stage animal studies. Evidence for PBDE-mediated effects from human studies in systems other than the developing nervous system, such as in cancer development, is inconclusive or non-existent. Particularly for the potential effects of PBDEs on the developing fetus, research has focused on the health status of mothers and gestational age of the infant.

Sediment contamination 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 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 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.

Regulations of PBDEs

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Worked examples

Example 1 — a first encounter with Polybrominated diphenyl ethers

Start with the simplest possible case. Write down what Polybrominated diphenyl ethers claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Polybrominated diphenyl ethers before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Polybrominated diphenyl ethers ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Polybrominated diphenyl ethers

In research: Polybrominated diphenyl ethers appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Polybrominated diphenyl ethers in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Polybrominated diphenyl ethers is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bromoarenes, Diphenyl ethers, Endocrine disruptors, so understanding it makes those chapters shorter.
In everyday life: Look for Polybrominated diphenyl ethers outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Polybrominated diphenyl ethers in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Polybrominated diphenyl ethers means in your own words.
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Frequently asked questions

What is Polybrominated diphenyl ethers in simple terms?

Why does Polybrominated diphenyl ethers matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Polybrominated diphenyl ethers?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Polybrominated diphenyl ethers.