Chitosan is derived from crustaceans, but the allergens in crustaceans are removed during the manufacturing process.
No, chitosan products (like CE-Clarifier) do not trigger seafood allergies. It is hypo-allergenic thanks to how it is processed. The allergy-causing proteins are destroyed.
What is chitosan?
Chitosan is a biopolymer with special properties that help coagulate particles in water. It is also used in many other applications, including medicine.1 It is derived from Chitin, a substance found in crustacean shells (crabs, lobsters, shrimp, crawfish, etc.).
Unlike synthetic polymers (many of which are petroleum-based), chitosan is all-natural. In water, it's strong charge attracts particles into larger groups for easier filtration, and sometimes enough to sink the particle (floccing).
In swimming pools, chitosan is a phenomenal clarifier. CE-Clarifier is chitosan-based, blended with CV-600 enzyme for extra strength and ability to affect surface tension. The enzyme breaks down and removes oils and non-living organics, and the chitosan attracts solid particles.
Allergens in seafood
While there have been very few instances of people with seafood allergies reacting with chitosan, according to the research, it's because those chitosan products were not fully processed. The process of destroying the allergen-causing proteins is called deproteination.2
Thankfully, this is extraordinarily rare, and in the use-case of swimming pools, the concentration of chitosan being used is very low to begin with. The study referenced in the footnotes below was about chitosan being injected directly into the bloodstream.
1 Aranaz, I., Alcántara, A. R., Civera, M. C., Arias, C., Elorza, B., Heras Caballero, A., & Acosta, N. (2021). Chitosan: An Overview of Its Properties and Applications. Polymers, 13(19), 3256. https://doi.org/10.3390/polym13193256
2 Peng, S., Liang, Y., Xiao, W., Liu, Y., Yu, M., & Liu, L. (2022). Anaphylaxis induced by intra-articular injection of chitosan: A case report and literature review. Clinical case reports, 10(12), e6596. https://doi.org/10.1002/ccr3.6596