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Hexabromocyclododecane as a possible global POP

image of Hexabromocyclododecane as a possible global POP

The objective of this report is to review the relevant information on a brominated flame retardant hexabromocyclododecane (HBCDD) in relation to the screening criteria of the Stockholm Convention on Persistent Organic Pollutants (POPs) and of the Protocol on Persistent Organic Pollutants of the UNECE Convention on Long-Range Transboundary Air Pollution for adding new substances to these instruments. Some additional information needed in the consideration of the possible nomination of the substance as a new POP is also provided. This joint Nordic project has been prepared by consultant Johanna Peltola-Thies and supervised by a project group under Bjørg Fjeld from the Norwegian Pollution Control Authority. The project was financed by the Nordic Council of Ministers through the Nordic Chemicals Group and the Nordic Sea and Air Quality Group.

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Information on hexabromocyclododecane in relation to the POP screening criteria

Photochemical degradation half-life of HBCDD in the atmosphere is estimated by AopWin v1.91 to be 76.8 hours (3.2 days). The model estimates the degradation rate for reaction with hydroxyl radicals. The estimate was obtained by assuming a concentration of 5 * 105 OHmolecules/ cm3 and that the reaction takes place 24 hours in a day (these are values used in the Europen Union risk assessments). It is noted, that the model is sensitive to the chosen OH-concentration. With a concentration of 7*106 OH-molecules/cm3 a degradation half-life of 0.23 days result. The model is not able to estimate other reactions (such as with ozone or NH4) in air for HBCDD and the estimates illustrate only the rate of hydrogen abstraction, which is primary degradation.

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