RC - What is RC? - Rotterdam Convention

2. Risk Evaluation
a) Key findings of the national risk evaluation
Hexachlorobutadiene is placed in the category of Class I Specified Chemical Substances based on the
following judgment.
1. Biodegradation: Based on the report of the biodegradation test with microorganisms, the percentage of
biodegradation is 6, 32, 33% and 5, 11, 7%, measured by BOD and by GC, respectively. Thereafter,
Hexachlorobutadiene is considered to be very persistent.
2. Bioaccumulation: Based on the report that BCF for fish exposed is 6,280 (high exposure level case)
and 7,720 (low exposure level case), Hexachlorobutadiene is considered to be very bio-accumulative.
3. Long-term toxicity: Histological renal abnormalities were observed in rats at 2 mg/kg/day of
Hexachlorobutadiene and higher in an approximately two-year study. When they were administered at 20
mg/kg/day, renal tubular adenoma and adenocarcinoma were observed. A reproductive toxicity study on
rats suggests that Hexachlorobutadiene decreases the weights of pups at 7.5 mg/kg/day and higher. The
same study also indicates that the chemical decreases the conception rate and inhibits implantation at 75
mg/kg/day.
b) Key data reviews consulted and a brief description
Biodegradation and Bioaccumulation data
http://www.safe.nite.go.jp/data/hazkizon/pk_e_kizon_disp.html?k_no=1637
c) Reference to national studies, eg toxicological and ecotoxicity studies
No information.
d) Summary of actual (potential) human exposure and/or environmental fate
Hexachlorobuta-1,3-diene in water and sediment was measured in 1981, but it was not detected in any
point. (limit of detection; water…0.02 ug/l, sediment…0.002~2 ug/g-dry)
3. Risk Reduction and Relevance to Other States
a) Estimates of the quantity of chemicals used, or imported/exported at the time of the regulatory
action and if possible information on ongoing trade
It was reported that there were neither manufacturing nor import in 2002.
b) Relevance to other States i.e. those with similar conditions of use
No information.
c) Comments on the typical use of the chemical within the notifying country, with comments on
possible misuse (if appropriate)
No information.
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