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Cyclopentasiloxane vs Recombinant Bovine Somatotropin: which is worse?

Quick answer: Recombinant Bovine Somatotropin carries the heavier risk profile. Cyclopentasiloxane is restricted in the EU and allowed in the US; Recombinant Bovine Somatotropin is in the EU and in the US.

PropertyCyclopentasiloxaneRecombinant Bovine Somatotropin
EU statusRestricted
US statusAllowed
Risk levelmedium
Banned inEuropean Union, Canada, Japan, Australia, New Zealand
Restricted inEuropean Union
Categoryendocrine disruptoradditive
Where it hideshair serum, primer, deodorant

What is Cyclopentasiloxane?

Cyclopentasiloxane is a volatile silicone (D5) used for smooth, silky texture.

What is Recombinant Bovine Somatotropin?

Recombinant bovine somatotropin (rBST) is the synthetic version of bovine growth hormone (BST), naturally produced by the pituitary gland in cattle. The recombinant version is produced using genetically engineered bacteria and is injected into dairy cows to increase milk production by 10-15%. Brand name: Posilac.

Documented risks

Cyclopentasiloxane: Persistent and bioaccumulative; the EU restricts D5 in wash-off products over environmental and endocrine concerns. The US has no restriction.

Recombinant Bovine Somatotropin: See recombinant-bovine-growth-hormone-rbgh for full detail. Key concerns: rBST elevates IGF-1 in milk; elevated blood IGF-1 is associated with breast, prostate, and colorectal cancer risk in epidemiological studies. Animal welfare: increased mastitis (up to 25-50% higher rates), lameness, and antibiotic use. The Codex Alimentarius Commission declined to endorse rBST safety MRLs in a historic 33-29 vote. Health Canada rejected rBST approval in 1999 after finding it caused significant animal health problems requiring increased antibiotic use.

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