Governmental commission, National Cemicals Inspectorate/Swedish EPA
- Priority list for chemicals to LRTAP and SC -
Annex 1 to the Interim Report
PRIORITISING OF POP-CANDIDATES
Pentabromo diphenyl ether (PentaBDE, PeBDE)
CAS No. 32534-81-9 (commercial mixture) PeBDE refers here to the commercial mixture of Pentabromo diphenyl ether that consists of Polybrominated diphenyl ethers with three to eight bromine atoms per molecule. The penta brominated molecules dominate in the mixture and contribute with more than 50% to the total amount whereas tetra- and hexa brominated molecules contribute with 24-28 % and 4-12 % respectively. The summary below is mainly based upon a Nordic report (1).
PeBDE is a brominated flame retardant mainly used in different polyurethane (PUR) applications as for furniture and upholstery in automotive industry and domestic furnishing. Other possible minor uses are in rigid polyurethane elastomers (e.g., in instrument casings), in epoxy resins and phenol resins (electric and electronic appliances). The global consumption of PeBDE in 1999 has been estimated to 8 500 tonnes of which only 210 tonnes was used in Europe.
According to a standard, OECD 301B ready biodegradability test, with aerobic activated sludge sewage treatment plant organisms, PeBDE is not readily biodegradable. Nevertheless, according to the results from a study with decabromo diphenyl ether, photolysis resulting in reductive debromination might be a possible pathway for abiotic degradation. The total (biotic and abiotic) half-lives of one tetra- and one penta brominated diphenyl ether in aerobic sediment has been estimated to 600 days and 150 days in water and soil. Findings of PeBDE related substances in remote regions also indicate high persistency. Thus, the criterion for persistency, seems to be met.
All components of PeBDE as well as of commercial PeBDE have a log Kow greater than 5, suggesting that they have potential to bio-accumulate. The bio-concentration factor (BCF) for commercial PeBDE in carp was estimated to 27 400, which is well above the criterion limit. In fish, BDE-47 is taken up more efficiently than CB-153, the PCB congener with the highest concentrations in biota. But both BDE-99 uptake and BDE-153 uptake in fish seems to be similar to those of other PCBs studied (-31, -52, -77 and -118). In mammals, the main components of PeBDE are taken up efficiently and excreted slowly by both rats and mice. The excretion in mammals is mainly faecal and uptake efficiency and elimination time correlates negatively with the degree of bromination. The presence of PeBDE in biota as fish, birds (guillemot and peregrine falcon) and human food as pork, lamb and beef (2) also support bioaccumulation. There are also findings indicating that PeBDE might biomagnify. The criterion for bio-accumulation is fulfilled.
In vitro studies of PeBDE have shown i.a., an ability to activate the Ah-receptor and possible genotoxicity (intragenic recombination). Immunotoxicity for the major PeBDE congeners has been shown in mice but not in rats. In vitro, several PeBDE congeners have been shown give rise to antiestrogenic response.
In vivo, studies of rats indicate that liver is the main target organ affected by PeBDE with a NOAEL of 1 mg/kg/d. Other studies have revealed i.a. developmental neurotoxicity in mice after a single dose of 0.8 mg/kg BDE-99 to 10 days old mouse pups.
Studies of algae and invertebrates indicate effects at exposure levels as low as 3-6 µg/l and larval development for a copepod Acartia tonsa showed disturbances after 5 days at 13 µg/l. The criterion for adverse effects is met.
Potential for long-range transport
PeBDE components have very low volatility. Vapour pressure between 9.6 x 10-8 - 4.7 x 10-5 Pa have been reported and the corresponding water solubility between 2 – 13 µg/l. The estimated Henry’s Law Constants (3) nevertheless suggest that at least the lower brominated components can also be volatilised in significant amounts from aqueous solutions. Vapour pressure and water solubility decreases with increasing bromination.
PeBDE congeners have been found in Arctic air at remote sites in Canada and Russia. Total concentrations were <1-28 pg/m3. At another remote Arctic area in Pallas, Finland, BDE-47 and BDE-99 concentrations were measured between 0.3-2 pg/m3. The same congeners were also observed at two Swedish sites, Ammarnäs and Hoburgen, remote from point sources. The sumPBDE concentration in the air varied in this study generally between 1 and 10 pg/m3. Also according to the atmospheric half-life estimates from SAR modelling, PeBDE has long-range transport potential in the atmosphere as the half-life I estimated to 10-20 days, which is well above criterion limit at 2 days.
The group “Polybrominated diphenyl ethers” is listed among priority substances under the EU water framework directive (4, 5). In this directive a mean concentration of PeBDE congeners in European sediment samples at 1.25 µg/kg, based on 16 samples (all positive) from 16 sites.
As the European market at this very day has adjusted its assortment of flame retardants to a product mix where PeBDE constitutes less than 1% , it is not likely that a regulation of this substance would result in any major conflicts. A ban within the EU is under way (6). As many countries have different standards for flame protection for different materials this might cause problems to regulate the current substances in e.g. the US, as their present use of PeBDE is 15% of the total consumption and still increasing.
Pentabromodiphenyl ether as a global POP. Tema Nord 2000:XX. Document can be found at: http://www.norden.org/miljoe/uk/PeBDEfinal.pdf.
Darnerud et al (2000) Organiska miljökontaminanter i Svenska livsmedel, Sakrapport till naturvårdsverkets miljöövervakningsnämnd. Report and data can be found at: http://www.imm.ki.se/national/.
COM, 2000. Risk Assessment of Diphenyl Ether, Pentabromoderivative (Pentabromodiphenyl Ether). CAS Number: 32534-81-9, EINECS Number: 251-084-2. Final Report of August 2000, Commission of the European Communities. Rapporteur: United Kingdom.
EU parliament and council. Water framework directive 2001/C 154 E/11, 29.5.2001 and Directive 2000/60/EG.
Fraunhofer-Institut (1999) Revised Proposal for a List of Priority Substances in the Context of the Water Framework Directive (COMMPS Procedure). Draft Final Report. Declaration ref.: 98/788/3040/DEB/E1. Schmallenberg, Fraunhofer Institut Umweltchemie und Ökotoxikologie.
Commission Recommendation 2001/194/EC.
Polychlorinated naphtalenes (PCN)
CAS No. 70776-03-3 (a mixture)
PCN was introduced on the market already in the 1920’s. The technical PCN is a mixture of congeners containing 1-8 chlorines per molecule. It has similar use areas as the more well-known PCBs, and they include cable insulation, wood preservation, engine oil additive, in electroplating, in dye production, in capacitors and in oils for refraction index measurements. Because of many cases of poisoning, especially in cattle, the use of PCN decreased in the 1970’s. Today, there is no known use in the industrialised world (1). Considering that the production is simple, one can’t rule out continuing manufacture in developing countries. Another important source of PCN, is the unintentional formation of PCN when chlorine-containing material is combusted under poor conditions (a high formation of PCN was observed when fly ash was heated at 300oC). The relative contribution from waste incineration, in relation to active use of PCN, seems to increase with time.
There are few reliable degradation studies on PCN. The available data indicate that the persistence increases with increasing degree of chlorination, and that PCNs with more than one chlorine would fulfil the persistence criterion (2). The ubiquitous presence of PCN in biota even today, and then mainly in mammals including humans (3), supports a very high persistence of highly chlorinated PCN.
For PCNs containing 2-5 chlorines, there are bioconcentration studies in fish showing a bioconcentration well above the criterion (BCF>5000) (1). The highest values (33 000) are reported for tetraCN, but the congeners with the highest potential (penta and hexaCN), as indicated from their presence in predatory animals, are not studied.
PCN is very toxic to most organisms, probably because of the structural resemblance with the chlorinated dioxines. In fish and crustaceans, LC50 values of 0.4-2.8 mg/l have been reported for mono-and dichlorinated PCNs. LC50 values of 0.008-0.44 mg/l have been reported for highly chlorinated technical mixtures in two fish species (1).
There are many cases of exposure of cattle to PCN (2), which indicate a high toxicity in mammals. Systemic effects were observed at exposure to 1 mg PCN/kg body weight/day. Effects were first observed on the skin, followed by anemia, liver damage, and finally even death (1, 2). One reason for the toxicity seems to be an imbalance in the vitamine A homeostasis, making it possible to classify PCN as a potential endocrine disruptor.
Potential for long-range transport
Photolysis experiments have shown a halflife of 2.7 days in air for dichlorinated PCN (1). QSAR-models indicate a halflife of 8-437 days for highly chlorinated PCNs (1). The criterion for long-range transport thus seems to be fulfilled, which is also supported by the presence of PCN in arctic air ( 49 pg/m3) (4). It should be noted that the air concentration of PCN is just a few times lower than the concentration of PCB in some air samples from the Arctic (4) and the UK (5).
OSPAR has prioritised PCN as of ”very high concern”, because of POP-like characteristics, but there is no known use in the EU. A decreasing global use of PCN is indicated by decreasing concentrations in the environment. A global regulation should in the first place be directed at making sure that any potential manufacturing in developing countries is stopped, as there are many alternative chemicals. Another purpose would be to encourage and support environmentally sound disposal of products containing PCN, as presently for the PCBs. Such disposal is presently required for PCB in the POP-conventions, but even if no new plants would be required, controlled destruction is costly. The biggest problem in fulfilling such a requirement for PCN-containing products still appears to be how to identify products that contain PCN. Those measures that are required by the conventions to reduce the unintentional formation of dioxines/furanes in combustion processes, may be sufficient to also reduce unintentional formation of PCN, and further measures may not be needed for that particular source.
Risk profile polychlorinated naphtalenes, Preliminary risk profile prepared for Ministry of Housing, Physical Planning and the Environment (VROM, the Netherlands) in the framework of the project Risk Profiles III, March 2002.
Environmental hazard assessment: Halogenated naphtalenes. Toxic Substances Division, Directorate for Air, Climate and Toxic Substances, Department of the Environment, UK, 1993
Norén, K. and D. Meironyté, Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20-30 years. Chemosphere 2000, 40, 1111-1123.
Harner et al, Polychlorinated naphtalenes and coplanar polychlorinated biphenyls in arctic air, Environ. Sci. Technol. 1998, 32, 3257-3265.
Harner et al, Polychlorinated naphtalenes in the atmosphere of the United Kingdom, Environ. Sci. Technol. 2000, 34, 3137-3142.
Hexachlorocyclohexane (HCH, including -HCH, lindane)
Technical HCH is a mixture of different isomeric forms (-, -, -, -, -) where the hydrogen and chlorine atoms have different spatial orientation on the carbon atoms of the hexane ring. Lindane contains >99% -HCH.
CAS No.: 608-73-1 (HCH), 319-84-6 (-HCH), 319-85-7 (-HCH), 319-86-8 (-HCH), 58-89-9 (-HCH, lindane).
This short summary is mainly based on data compiled in two WHO documents (1,2) and on a draft produced within the context of the OSPAR Convention (3). In addition, information has been taken from reports on monitoring and from reports generated within the EU review of active ingredients in plant protection products (4). It should be noted that a background document on lindane is in preparation for UN ECE in the context of the Convention on Long Range Transboundary Air Pollution (LRTAP) (3).
Only -HCH shows a significant insecticidal activity. Purification of lindane from HCH produces the remaining isomers (mainly - and -) which are used as intermediates in the production of trichlorobenzene, hydrochloric acid and other chemicals (1). Isomerization of lindane does not seem to occur in the environment, whereas slow isomerization of -HCH occurs (2).
HCH has been produced commercially since 1949 (1). Until the end of the 1970's isomeric mixtures of -, - and -HCH were commonly used as insecticides in agriculture and as wood preservatives, however, in most countries where HCH is still used, the use is restricted to -HCH. EU Member States put an end to the use of technical HCH in 1979 by Directive 79/117/EEC. It appears that technical HCH is still used in some Eastern European countries (3). Still in 1986-87, approximately 27 000 tonnes of technical HCH was used in India (1). In 1970, the usage of -HCH was estimated to be
25 000 on an European basis, while the usage in 1996 was only 366 tonnes (3). The major part of the remaining use of -HCH in 1996 has (however with uncertainty) been attributed to use in Eastern Europe (3). A similar decrease has been observed for -HCH.
Lindane has a wide use in agriculture and forestry (for seed treatment and soil application), in household biocidal products (e.g. treatment of animals, ornamentals and turfs), as wood and textile preservative, and also in medical control of ectoparasites on humans and animals (3). The world production of lindane was estimated to approximately 38 000 tonnes in 1986 (3); but to only about
3 200 tonnes per year during the period 1990-1995 (3). Within the OSPAR Convention area the non-agricultural use has been judged as insignificant (3). However, according to a questionnaire in 1997, some non-agricultural use of lindane was important in the United Kingdom and in Belgium (3).