IARC Classifies 3 Plastic Plasticizers, Phthalates, as 'Possibly Carcinogenic' Group 2B

The International Agency for Research on Cancer (IARC) classified all three phthalate plasticizers, which soften plastics, as 'possibly carcinogenic to humans (Group 2B)': butyl benzyl phthalate (BBzP), dibutyl phthalate (DBP) and diisononyl phthalate (DINP). The summary of the evaluation appeared in The Lancet Oncology, and details will be published in IARC Monographs Volume 142.

For all three, the evidence of cancer in humans was judged 'inadequate.' Evidence of carcinogenicity in animals was 'sufficient' for BBzP and DINP and 'limited' for DBP, and the mechanistic evidence was rated 'strong' for all three. These are high-production-volume chemicals used mainly in flexible polyvinyl chloride (PVC) such as flooring and electrical cables, and they are also found in adhesives, paints and cosmetics. They are detected throughout the environment, including air, water, dust and food, and biomonitoring also shows broad exposure in the general population. Occupational exposure was cited for workers in PVC processing and recycling, nail salons and health care.

What Group 2B means

Group 2B is the category with the lowest level of evidence among IARC's carcinogenicity categories, and in this evaluation as well there was almost no human evidence. An IARC classification indicates only the strength of the evidence on a possible hazard and says nothing about the size of the risk at a given exposure level. Many countries already restrict the use of these substances in toys, childcare products and some food contact materials. The actual risk from food must be judged together with the risk assessments by food safety authorities, which weigh dietary exposure.