Polybrominated diphenyl ethers

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Structure of polybrominated diphenyl ethers; 1 ≤ (m + n) ≤ 10

Polybrominated diphenyl ethers ( PBDE ) are bromine-containing organic chemicals that are used as flame retardants in many plastics and textiles. The PBDE family consists of a total of 209 different individual compounds, which are also referred to as congeners (PBDE = C 12 H 10 − x Br x O (1 ≤ x ≤ 10)).

history

Three different technical grade PBDE blends have been made for over thirty years and used in countless applications. PentaBDE , the mixture with the lowest degree of bromination, has been in use since the late 1960s. Large amounts of PBDE have been used over the years, resulting in the formation of a significant deposit in products and in landfills . In principle, substances in such stores have the potential to get into the environment during use, but also during disposal of the products. PBDE are so-called additive flame retardants, i.e. That is, they do not react with the plastics during the production process, but are only mixed with the polymer . Because PBDEs are only slightly water-soluble, have a low vapor pressure and it was assumed that they are firmly embedded in the polymers, the possibility of emissions into the air or leaching into water was not specifically considered during product development. Only after the analytical methods had been improved could the substances be detected in indoor air. The outgassing from products could thus be demonstrated. In the early 1980s, pentaBDE was found in fish near industrial users. When PBDE was also found in seals and sea birds from the Baltic Sea region at the end of the 1980s , the large-scale distribution of the substances became clear.

During the 1990s, the increasing concentrations of pentaBDE in the environment caused increasing concern, first in biota, then in human milk. Further advances in analytical methodology made it possible to determine pentaBDE concentrations down to the trace range. PentaBDE was found in workers involved in the production and recycling of electrical and electronic equipment as well as in non-exposed persons. When a study of stored human milk samples found that the concentrations of PentaBDE increased exponentially between 1972 and 1997, action was required.

Germany and Sweden were among those countries that reacted early to the rising concentrations of PentaBDE in humans. German industry agreed to voluntarily cease its use in 1986. In 1999, production and use were banned in Sweden.

Risk assessment

All commercial PBDE products have undergone a detailed risk assessment within the framework of the EU Regulation on Existing Substances 793/93 / EEC. As a result, PentaBDE and OctaBDE have been banned as they accumulate in the environment, are persistent and toxic. As a PBT and vPvB substance, DecaBDE is on the list of substances of very high concern that are eligible for authorization and will be Template: future / in 5 yearssubject to extensive restrictions from March 2, 2019 . All three PBDE products have also been included in Appendix A of the Stockholm Convention .

Application prohibitions

PentaBDE and OctaBDE were banned in 2003 by the European Directive 2003/11 / EC because of the risk to the environment and the preventive protection of breastfed infants. Substances, preparations and products with a content of more than 0.1 percent by weight PentaBDE or OctaBDE may no longer be placed on the market or used. The Chemicals Prohibition Ordinance implemented the ban in German law on June 30, 2004. It applies to any type of product.

Previously, the European Directive 2002/95 / EG ( RoHS ) had already stipulated that from July 1, 2006, no more electrical and electronic devices with more than 0.1 weight percent PBDE per homogeneous may be placed on the EU-wide market Material included. This guideline was implemented in Germany in the Electrical and Electronic Equipment Act (ElektroG of March 16, 2005). The substance DecaBDE was later exempted from the ban. However, on July 1, 2008, this exception was lifted again.

Analytical evidence

The chemical-analytical detection in environmental samples, food and animal feed is carried out after suitable sample preparation to separate the matrix and gas chromatographic separation of minor components by high-resolution mass spectrometry techniques such as flight mass spectrometry (Time-Of-Flight mass spectrometry).

properties

PBDEs have a diphenyl ether backbone (two benzene rings linked via an oxygen atom ) on which one or more hydrogen has been replaced by bromine atoms . The general empirical formula is thus C 12 H 10 − x Br x O. There are many different congeners and many more corresponding derivatives, but only a few of them occur in commercial products.

Overview of the congeners with the same degree of bromination
PBDE homolog CAS number Br substituents Number of congeners
Monobromodiphenyl ether 101-55-3 (4-MBDE) 1 3
Dibromodiphenyl ether 2050-47-7 (4,4'-DBDE) 2 12
Tribromodiphenyl ether 49690-94-0 3 24
Tetrabromodiphenyl ether 40088-47-9 4th 42
Pentabromodiphenyl ether 32534-81-9 5 46
Hexabromodiphenyl ether 36483-60-0 6th 42
Heptabromodiphenyl ether 68928-80-3 7th 24
Octabromodiphenyl ether 32536-52-0 8th 12
Nonabromodiphenyl ether 63936-56-1 9 3
Decabromodiphenyl ether 1163-19-5 10 1

use

Mainly three technical PBDE mixtures that differ in the number of bromine atoms in the molecule are / were used as flame retardants : PentaBDE , OctaBDE and DecaBDE . PentaBDE and OctaBDE have not been produced in Europe or North America since 2004. The pentaBDE and octaBDE mixtures used contain various congeners, each containing four to six or six to nine bromine atoms per molecule. In addition to the main component - BDE-209 - DecaBDE contains small amounts of less brominated derivatives . PentaBDE was mainly used to equip flexible and rigid polyurethane foam with flame protection. Soft foam is used for furniture, carpet underlays and vehicle interiors, while rigid foam is used as an elastomer in housings. OctaBDE was used in thermoplastics , although it was widely used in injection molding applications such as HIPS . DecaBDE is still used in textiles. In the USA, the use of DecaBDE has been voluntarily dispensed with since 2012. For some applications (e.g. transport, military) the deadline has been extended by one year.

Environmental relevance

The lower brominated PBDE, i.e. H. PentaBDE and OctaBDE, have a toxic character and are possibly carcinogenic and hormone-active . In general, one can say that the toxicity increases with decreasing degree of bromination. They have been detected in animal tissue, as well as in water and sediment samples far away from their source, so that concerns about their global effects are increasing. The concentrations of penta and octaBDE components in the environment have risen sharply and in some regions of the world are approaching the concentrations of PCBs . Use of sewage sludge as a fertilizer in agriculture, recycling processes and landfill are the main entry routes of PBDE into the environment. Due to the reduced use of these substances in Europe since the mid-1990s, the environmental concentrations in Europe are now partially falling.

Related links

Individual evidence

  1. ↑ O. Anderson, G. Blomkvist: Polybrominated aromatic pollutants found in fish in Sweden . Chemosphere , 10: 1051-1060 (1981).
  2. ^ B. Jansson, L. Asplund: Brominated flame retardants - Ubiquitous environmental pollutants? Chemosphere, 16: 2343-2349 (1987).
  3. ^ MG Ikonomou, S. Rayne, RF Addison: Exponential increases of the brominated flame retardants, polybrominated diphenyl ethers, in the Canadian arctic from 1981 to 2000 . Environmental Science & Technology , 36 (2002), 1886-1892.
  4. ^ K. Betts: Rapidly rising PBDE levels in North America . Environmental Science & Technology - Science News, 36 (2001), 50A-52A. PMID 11871568
  5. ↑ A. Sjödin, DG Patterson, A. Bergman: A review on human exposure of brominated flame retardants - Particularly PBDEs . Environment International , 29 (2003), 829-839.
  6. ↑ D. Meironyté, K. Norén, A. Bergman: Analysis of polybrominated diphenyl ethers . In: Journal of Toxicology and Environmental Health , 58 (1999), 329-341.
  7. ↑ DIRECTIVE 2003/11 / EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL dated February 6, 2003 on the 24th amendment to Directive 76/769 / EEC on restrictions on the placing on the market and use of certain dangerous substances and preparations (pentabromodiphenyl ether, octabromodiphenyl ether) (PDF ; 162 kB).
  8. ↑ ECHA : Annex XVII to REACH - Conditions of restriction: Restrictions on the manufacture, placing on the market and use of certain dangerous substances, mixtures and articles: Entry 67 , 2017.
  9. ↑ Eric J. Reiner, Adrienne R. Boden, Tony Chen, Karen A. MacPherson and Alina M. Muscalu: Advances in the Analysis of Persistent Halogenated Organic Compounds . In: LC GC Europe . 23 (2010) 60-70.
  10. ↑ Hans-Ulrich Maier: Analysis of environmental samples - Qualitative and quantitative analyzes of PVBs and PBDEs , LABO, May 2010 , 8–9.
  11. ↑ Agency for Toxic Substances and Disease Registry: Polybrominated Biphenyls and Ethers (PDF; 345 kB).

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