Toxicity of colloidal silver products and their marketing claims in Finland

Graphical abstract
Highlights • Silver nanoparticles and silver ions in colloidal silver are toxic. • Internet marketing of colloidal silver included false claims. • Internal use of colloidal silver was promoted by companies and users. • Distrust in authorities expressed in websites and Facebook nulled interventions.
Aims The aim was to investigate the marketing practices, beliefs and health claims regarding the use of colloidal silver in Finland. Silver nanoparticles (AgNPs) are potentially toxic due to their small size and Ag+-release capabilities, and the use of colloidal silver products containing AgNPs can cause a wide variety of adverse effects such as argyria. Methods Contents of three company websites selling colloidal silver were reviewed, and the claims used in the marketing of colloidal silver were compared to the scientific information about silver. In Facebook posts and discussion about colloidal silver were analyzed. Results In Finland, the marketing of colloidal silver products on websites selling the products did not follow the regulations of authorities; several scientifically unfounded claims about the efficacy and medical use of colloidal silver were found. After the Finnish Broadcasting Company (Yle) documentary and an intervention by authorities, contents of the websites were changed, but still questionable information and misleading claims could be found. In the analyzed Facebook groups attitudes towards medical use of colloidal silver were uncritically positive, internal use was highly promoted and the restrictions of use were considered unjustified. Conclusions The use of quackery products such as colloidal silver can be dangerous, and their use and marketing should be controlled and restricted.