bpc-157 toxicity animal studies Frontiers JPP No 5/2013 article 09

Regulatory and Anti-Doping Context Athletes may need to consider anti-doping rules, supplement contamination risk, banned-substance lists, governing-body policies, team requirements, and professional guidance before using any supplement or peptide-related product

And some simply don't like how it feels in their hair

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, a preservative that stops bacterial growth so a single vial can be used multiple times over roughly 28 days

Preservative-Enhanced: Contains 0.9% benzyl alcohol to inhibit bacterial growth, supporting multiple withdrawals for medication reconstitution