I am confused, are silicones bioaccumulative?

SylSyl Member
edited November 2021 in Science
Hi All,
I have been getting so many mixed messages regarding silicones lately.

Belinda Carli from the Institute of Personal Care Science says they are degraded and safe.

A search in Pubmed says that dimethicone and cyclotetrasiloxane are degraded in the environment and are ok, but the study was paid for by Dow Corning https://pubmed.ncbi.nlm.nih.gov/18505514/ .

On the other hand, Credo Beauty says the opposite; silicones are on the dirty list. https://cdn.shopify.com/s/files/1/0637/6147/files/The_Dirty_List_PDF_August_Update.pdf?v=1598294504  and EWG has confusing information which seems to be in line with Credo. What is Credo's motive?

Out of exasperation, I did a Google Scholar search and I found this article https://www.proquest.com/openview/824e59bd102d70d9235bb2f64aa76b64/1?pq-origsite=gscholar&cbl=32741
It says; silicones, polymers and quats are poorly biodegradable.  Thanks to wastewater treatment, clay catalized- hydrolysis and photo-mineralization, they are either processed or removed. They are not persistent, and are monitored.

Please share if you have any additional information.

Thanks,

Syl
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Comments

  • PerryPerry Administrator, Professional Chemist
    I guess it comes down to where you get your information from.

    Credo Beauty is a marketing company. They do not do any research themselves. The information they provide should not be taken as serious and can be mostly dismissed as biased information. They benefit from scaring consumers away from buying standard beauty products into buying more expensive, less effective beauty products. This is their motivation.

    Similarly, the EWG is a fear mongering group and any information that they publish can also be be dismissed. They do not do ANY research themselves.

    This is not to say that they are necessarily publishing misinformation, but at best they are publishing second hand information that they specifically translate into something that supports the marketing or fear narrative that they want to communicate.  

    Bottom line is that you should go to the direct sources and ignore indirect sources like EWG and Credo.

    Belinda is well-meaning and provides less biased information, but she is not an expert in the environmental impact of ingredients. Like the other two sources she provides second hand information. I would trust her information over the other two examples but none of them are wholly reliable because they don't directly do the research.

    So, you have to go to the research.  This research article says they can be biodegraded. - http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.612.8864&rep=rep1&type=pdf

    So  does this article - https://journals.asm.org/doi/pdf/10.1128/aem.65.5.2276-2278.1999

    Granted these articles don't say specifically that high molecular weight silicones are biodegraded in the environment, but at least under specific conditions silicones are biodegradable. In waste water, they are degraded.

    And the research from Dow Corning isn't necessarily inaccurate but it's worth being a bit skeptical. They certainly wouldn't publish data that says the product they sell is building up in the environment. However, they also aren't going to wholly make up a biodegradation mechanism which is what the paper describes. So, I would be confident that under the right conditions silicones do degrade in the environment. 

    If you really want to immerse yourself in the subject here is a review paper published by people who are actual environmental scientists.   

    They say "...knowledge of siloxanes’ environmental behavior and fate is surprisingly scarce as compared to their material flows and economic significance."

    And conclude that "While there was much progress in organosiloxane analytics during the past decade, fundamental research on their fate in the various environmental compartments did not keep pace."

    Basically, we don't know & more research is required.
  • @Perry Thank you very much. It is sad to see so much disinformation. 
  • Thanks @Perry
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