In a recent blog post, we discussed the proposed changes to the potency of polycyclic aromatic hydrocarbon (PAH) mixtures, including coal tar sealants. There are 18 new PAH chemicals being recognized for their toxicity in addition to the previous 6. One of those new chemicals is benzo[c]fluorene, which is also known as benzofluorene or 7H-benzo[c]fluorene.
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| Benzo[c]fluorene |
While some researchers have been looking at the toxic effects of this for several years, it is new to many of the rest of us. For example, if you look at the National Institute of Standards and Technology’s Certificate of Analysis Standard Reference Material® 1597a, Complex Mixture of Polycyclic Aromatic Hydrocarbons from Coal Tar, 70 different PAH compounds are listed–but not benzo[c]fluorene (BcF).
One industry reference says there is about 1 unit of benzo[c]fluorene for every 3 units of benzo[a]pyrene (BaP) in coal tar pitch samples. However the proposed EPA standard for toxicity lists it as 20 times more toxic than BaP, which is the yardstick that all PAH toxicity is measured by. This product alone may increase the toxicity of coal tar materials 6 times and account for more than half of the measured toxicity of a coal tar sample. By this measure, it is extremely toxic and most likely in coal tar containing products in common use.
What else do we know about this PAH?
- isolated cause of lung cancer in lab rats fed coal tar
- present in cigarette smoke
- recommended to be added to list of PAHs in food monitored by the EU
I suppose we will continue to learn more about this chemical in the months and years ahead.