The International Agency for Research on Cancer (Iarc) has concluded that 1,2-dichloropropane is a Group 1 substance, meaning it is “carcinogenic to humans”.
This represents a significant change in the status of the substance declared by the agency. Its previous assessment, published in 1999, put it in Group 3, that is “not classifiable as to its carcinogenicity to humans”.
The substance is used as an intermediate in the production of perchloroethylene and other chlorinated chemicals.
It has a mandatory carcinogen category 1B classification under the EU CLP Regulation. During the consultation, one of the REACH registrants, Dow Deutschland, proposed a less severe category 2 classification but the Risk Assessment Committee deemed this insufficient.
In addition to 1,2-dichloropropane, Iarc assessed the following four substances, also widely used as solvents and in polymer manufacture:
- perfluorooctanoic acid (PFOA);
- dichloromethane; and
- 1,3-propane sultone.
Tetrafluoroethylene, dichloromethane and 1,3-propane sultone have been moved from Group 2B, “possibly carcinogenic to humans”, the 1999 assessment, to Group 2A, “probably carcinogenic to humans”. Meanwhile, PFOA has been put in Group 2B.
PFOA is on the REACH candidate list for authorisation, making it a substance of very high concern (SVHC). But as a result of being toxic for reproduction and persistent, bioaccumulative and toxic (PBT) rather than carcinogenic.
In June, US Senator Kirsten Gillibrand (D-New York) urged the EPA to prioritise a regulatory assessment of PFOA under the new TSCA, the country's recently reformed major chemicals law, citing cancer concerns.
Tetrafluoroethylene does not have a mandatory EU carcinogen classification but dichloromethane does as category 2. It is undergoing substance evaluation under REACH for several hazard endpoints, including carcinogenicity.
1,3-propane sultone has a mandatory carcinogen category 1B classification under EU CLP and is on the candidate list for authorisation on account of carcinogenicity.
The assessments have been published as Iarc monographs, available free online.