I try to calculate characterization factors for MMA. When I compared my results with the characterization factors USEtox published in a list, I realised that there was a result for Human health effect factor_Inhalation_Cancer even if I found out that MMA does not represent a carcinogenic hazard to humans. How could it be?
Thank you for your question.
Assuming that with "MMA" you refer to the substance Methyl methacrylate (CAS 80-62-6), the human health effect factor related to cancer [cases per kg intake] for that substance in USEtox™ is truly zero (i.e. negative test result in the underlying study testing for carcinogenic effect in contrast to missing data, for which effect factors are given as "n/a") for both inhalation and ingestion. Hence, characterization factors based on these effect factors for that substance are also all zero.
For further information about human health effect factors see Rosenbaum et al. (2011).
Grateful to your for letting know that MMA does not represent a carcinogenic hazard to humans.
Lauren