Polybrominated diphenyl ethers

Polybrominated diphenyl ethers ( PBDEs) are brominated organic chemicals, which are used as flame retardants in many plastics and textiles. The PBDE family consists of a total of 209 different individual compounds, also known as congeners (PBDE = C12H10 - xBrxO ( 1 ≤ x ≤ 10) ) are known.

History

Three different technical PBDE mixtures were prepared for over thirty years and used in countless applications. PentaBDE, the mixture with the lowest degree of bromination has been used since the late 1960s. For years, large amounts of PBDEs have been used, which has led to the formation of a significant bearing in products and in landfills. Basically substances have to go in such bearings, the potential during use, but also during the disposal of the products into the environment. PBDE are so-called flame-retardant additives, i.e., they react during the preparation of the plastics are not using this, but are only mixed with the polymer. Because PBDEs are only slightly soluble in water, have a low vapor pressure and it was assumed they were firmly embedded in the polymers during the product development, the possibility of air emissions or leaching has not been specifically considered in the water. Only after the analytical methods had been improved, the substances could be detected in indoor air. The outgassing from products could thus be shown. Beginning of the 1980s, was found near industrial users pentaBDE in fish. When he was found also found in seals and sea birds from the Baltic Sea region at the end of the 1980s, PBDEs, the large-scale distribution of the substances was clear.

During the 1990s, the increasing concentrations of pentaBDE in the environment triggered increasing concern from, first in biota, then also in human milk. Further advances in analytical methodology allowed the determination of pentaBDE concentrations down to the track area. Both workers from the production and recycling of electrical and electronic devices as well as in non-exposed persons pentaBDE was found. As was noted in a study of stored human milk samples, the concentrations of pentaBDE recorded an exponential increase 1972-1997, measures were required.

Germany and Sweden among those countries that responded early to the increasing concentrations of pentaBDE in humans. The German industry agreed to a voluntary cessation of the use in 1986. In Sweden, the production and use was banned in 1999.

Risk assessment

All commercial PBDE products have undergone a detailed risk assessment under the EU Existing Substances Regulation 793/93/EEC. As a result pentaBDE and octa-BDE were banned because they accumulate in the environment, are persistent and toxic. However, no risk to humans and the environment, decaBDE was found.

Restrictions on use

PentaBDE and octa-BDE were banned in 2003 with the European Directive 2003/11/EC because of the threat to the environment and breast-fed infants for preventive protection. Substances, preparations and products containing more than 0.1 weight percent pentaBDE or octa-BDE may no longer be marketed or used in the traffic. The Regulation of Chemical Interdiction put the ban June 30, 2004 in German law. It refers to any type of product.

Prior to 2002/95/EC ( RoHS) was already by the European Directive has been determined that no EU-wide electrical and electronic equipment more may be placed on the market after 1 July 2006, more than 0.1 percent by weight of PBDE in homogeneous material included. This Directive was implemented in Germany in the electrical and electronic equipment (ElektroG of 16 March 2005). Later, the substance decaBDE was exempted from the ban. On 1 July 2008, this exception, however, was canceled.

Analytical detection

The chemical- analytical detection in environmental samples, food and feed can be performed with chromatographic methods.

Properties

PBDE having a skeleton of diphenyl ether (two via an oxygen atom linked to the benzene rings ) to which one or more hydrogen are replaced by bromine atoms. The empirical formula is therefore C12H10 - xBrxO. There are many different congeners and yet far more appropriate derivatives, of which only a few occur in commercial products.

Use

Are used / were mainly three technical PBDE mixtures, which differ by the number of bromine atoms present in the molecule: pentaBDE, octa-BDE and deca-BDE. Since 2004 pentaBDE and octa-BDE are no longer produced in Europe and North America. The pentaBDE and octa-BDE mixtures used contain different congeners, each containing four to six and six to nine bromine atoms per molecule. DecaBDE contains the main component - BDE -209 - small amounts of lower brominated derivatives. PentaBDE was mainly used for soft and hard foam made ​​of polyurethane fitted with flame retardants. Soft foam is used for furniture, carpet underlay and interiors of vehicles, rigid foam as an elastomer in enclosures. The application range of octa-BDE were thermoplastics, where it was commonly used in injection molding applications such as HIPS. DecaBDE is still used in textiles. In the United States is waived in 2012 voluntarily to the use of decaBDE. For some applications (eg, transportation, military) has extended the deadline by one year.

Environmental relevance

The lower brominated PBDE, ie pentaBDE and octa-BDE, have toxic character and may be carcinogenic and endocrine disruptors. Generally one can say that the toxicity increases with decreasing degree of bromination. They were in animal tissues, and detected in water and sediment samples far away from its origin source, so that the concern rises about their global impact. The concentrations of penta-and octa-BDE constituents in the environment have risen sharply, approaching in some regions of the world the concentrations of PCBs on. Use of sewage sludge as fertilizer in agriculture, recycling and disposal process are the main pathways of PBDEs in the environment. Due to reduced use of these substances in Europe since the mid- 1990s, the environmental concentrations in Europe are now partly declined.

Related compounds

• Chlorphenylid, halogenated diphenyl ethers
• Polybrominated biphenyls ( PBB), structurally similar bromoaromatics
• Decabromodiphenylethane