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Switzerland - Final Regulatory Action
Dichloro[(dichlorophenyl)methyl]methylbenzene CAS number:
Date circular:

Chemical name: Benzene, dichloro[(dichlorophenyl)methyl]methyl-, Benzene, dichloro[(dichlorophenyl)methyl]methyl-

Final regulatory action has been taken for the category: Industrial

Final regulatory action: The chemical is Banned

Use or uses prohibited by the final regulatory action:

Annex 1.1, ORR Chem: The manufacture, the placing on the market , the import for private use and use of halogenated organic compounds (like the monomethyl-tetrachloro-diphenyl methane and the monomethyl-dichloro-diphenyl methane), as well as preparations containing them, are banned.
Annex 2.14, ORRChem: The placing on the market and the import in a private capacity of capacitors and transformers containing pollutants are banned. Capacitors and transformers are considered to contain pollutants if they contain substances or preparations that are contaminated with monohalogenated aromatic substances (more than 500 ppm) or polyhalogenated (more than 50 ppm). Moreover, the capacitors constructed in 1982 or before are considered to contain pollutants as long as their owner doesn't prove the opposite.

Use or uses that remain allowed:

Exceptions of Annex 1.1:
a.Substances used for research and analytical purposes
b.intermediate products that undergo complete chemical conversion
c.oils and lubricating oils manufactured from used oils containing maximally 1 ppm halogenated biphenyls.

The final regulatory action was based on a risk or hazard evaluation: No

Summary of the final regulatory action:

In Switzerland, Ugilec has never been produced or imported. Both Ugilec 141 and 121 are banned since the 1980s in the European Community and have also been banned in Switzerland. The manufacture, the import, the placing on the market and the use of these substances are banned since 1988. The ban is reported in the new Ordinance on the Reduction of Risks linked to Chemical products (ORRChem) in Annex 1.1 on the halogenated organic compounds.
Moreover, the placing on the market of capacitors and transformers that contain halogenated aromatic substances like Ugilec is banned in Switzerland since 1986. At that time, the capacitors and transformers of a total mass higher than 1kg were to be registered by the cantonal authority and put out of operation and eliminated not later than 31 August 1998. The ban is reported in the ORRChem in Annex 2.14 on capacitors and transformers.

The reasons for the final regulatory action were relevant to: Human health and environment

Summary of known hazards and risks to human health:

Measured data on persistence, bioaccumulation and toxicity of Ugilec are scarce and difficult to undertake, due to a very low water solubility of the substances and its varying composition of congeners. However, structural analogies to PCBs have been employed to study the toxicological and ecotoxicological effects of TCBTs. In addition, test results have been provided by manufacturers.
Rats: LD50 oral of 3 300 mg/kg. In a subchronic study effects were observed at doses of 500 mg/kg/d over a 28 day period. A mortality rate of 20% was observed at this concentration.
Rabbits: LD50 Dermal >2000 mg/kg (14 day study)
Daphnia: IC50 of 0.4 mg/l (24 hours), LC50 of 0.4 - 1.6 mg/l
Algae: IC50 of 5 - 25 mg/l (depending on species)
Fish: no mortality was observed up to concentrations of 400 mg/l at an exposure period of 48 hours.
It should be noted that most of the test results were not obtained in tests compatible with international guidelines. Their outcomes should therefore be considered as indicative.
Toxicokinetics Given that TCBTs are physicochemically comparable to PCBs, similarities between TCBTs and PCBs can be expected in terms of their toxicokinetics, including a slow elimination of TCBTs from the organism and accumulation in adipose tissue. Thus TCBTs can pose risks similar to those posed by PCBs and other polyhalogenated hydrocarbons eg Arochlor 1254 and 3,3',4,4'-tetrachlorobiphenyl inducing comparable biochemical changes, such as enzyme induction, in both mice and rats (although the effects were less pronounced for Ugilec 141). It has been suggested that the limited accumulation and limited cytochrome P-450 (CYP) induction are explained by a relative rapid biotransformation of TCBTs. TCBTs are much more rapidly metabolised than PCBs. Thus TCBTs show a lower potential than PCBs for accumulation in humans. Fish have a lower metabolic capacity, thus accumulation of TCBTs occurs. The oral bioavailability of the TCBTs is lower than that of PCB 77, 101, and 118, which is due to the high first-pass elimination of the TCBTs that most likely occurs in the small intestines rather than in the liver.
CYP2B and CYP3A play an important role in the metabolism of the selected TCBTs and the non-planar PCBs, while the planar PCBs are metabolised by CYP1A enzymes. These enzymes are significantly expressed in the liver, the small intestines and the lungs. Thus these tissues can also contribute to the overall elimination of the TCBTs and the PCBs.
Human health implications relative to LRTAP (Long Range Transboundary Air Pollution)
In June 1993, a German assessment report (Umweltbundesamt 1993) suggested that the oligochlorobenzyltoluenes (Ugilec 141, Ugilec 121 and Ugilec T) were unsafe substitutes for PCBs on ecotoxicological, toxicological and safe-handling grounds. Significant environmental contamination has already been documented in the vicinity of mines where these substances have been used as hydraulic fluid. In the even of a fire involving any equipment containing Ugilec 141 or 121, highly toxic substances including PCDFs and PCDDs may be given off.
The most toxic PCBs induce their dioxin-like toxicity via interaction with the Ah-receptor. They have a coplanar conformation, which is an important requirement to interact with the receptor. One study has been performed to estimate, which TCBTs could adopt a coplanar conformation and could possibly interact with the Ah-receptor. Only two TCBTs could interact with the receptor and would induce dioxin-like toxicity.

Expected effect of the final regulatory action in relation to human health:

Prevention of bioaccumulation of Ugilec 141 and 121 in the environment. Prevention of adverse effects caused by the presence of these substances.

Summary of known hazards and risks to the environment:

Bioaccumulation: As TCBTs have structural and physicochemical similarites with PCBs, food chain accumulation of TCBTs was expected.
Rat - weak accumulation of Ugilic 141. After 4 weeks application of 500 mg/kg per day, levels of <100 ug/g fatty tissue and <5 ug/g liver were found. Two weeks later, the concentrations had dropped by 90 - 97.5%
In vitro studies: in vitro studies on hepatic microsomes showed that transformation rates for Ugilec 141 range from 0.96 to 4.14/hour for rats and from 0.009 to 0.017/hour for trout.
Fish: Levels of TCBTs of between 0.1 and 25 mg/kg bw were found in rivers in the vicinity and downstream of coal mines in Germany. These levels were comparable to those of PCBs, suggesting that the two substances have a similar accumulation pattern. Levels up to 24.9 mg/kg fish tissue have been reported.
For guppy fish (Poecilia reticulata) log BCF values range from 1.67 to 2.68. In adipose tissue of eel from rivers in the Netherlands, concentrations were found at levels of 0.1 - 1.2 ug/kg. On the other hand in fish from German rivers which received waste water from coal mines Ugilec was found at levels comparable to those of PCBs after changeover from PCB to Ugilec 141, suggesting an accumulation trait for Ugilec 141 similar to that of PCBs. Measure concentrations were thereby in a range of 0.1 to 25 mg/kg tissue.
After an exposure of fish over periods of 17 - 25 days in a flow through system at 1 mg/l Ugilec 121, a bioaccumulation factor of 12 500 was determined by the manufacturer. No clearance time could be determined in this experiment owing to a 74% mortality rate after 30 days.
Zebra mussels: Bioconcentration studies including eight isomers of Ugilec 141 on zebra mussels (Dreissena polymorpha) resulted in log BCF values spanning from 4.43 to 5.19. These considerably lower values for fish were attributed to higher biotransformation rates compared to mussels.
Persistance in water, soil and sediment: No valid laboratory tests on biodegradability, performed according to standardized guidelines, are available. The outcome of tests submitted by manufacturer of Ugilec 121 nevertheless indicated "moderate" biodegradability after adaptation of the inocullum. On the other hand, there is evidence of persistence of Ugilec 141 in river sediments in the vicinity and downstream of coal mines in Germany that used Ugilec. Contamination caused by leakage from hydraulic devices entered the rivers via mine effluents. While PCBs were found in sediments down to depths of 1.5 m, Ugilec took their place in the top lazers, temporally coincident with the companies' switch from PCBs to Ugilec.
Although Ugilec 141 and Ugilec 121 are less toxic and less bioaccumulative from laboratory test results measured environmental concentrations in fish and sediment give strong evidence fo an accumulation behaviour comparable to that of PCBs.

Date of entry into force of the final regulatory action: 01/08/2005