Barium carbonate (BaCO3) is used to create a unique glaze color known as barium blue. However, the ethical nature of using barium carbonate for glazes on food contact surfaces has come into question. Barium poisoning by ingestion can result in convulsions, paralysis, digestive discomfort, and death. It is also somewhat soluble in acid, and can contaminate water and soil for long periods of time. These concerns have led to attempts to substitute Strontium carbonate (SrCO3) in glazes that require barium carbonate. Unlike Barium carbonate, Strontium carbonate is not considered a safety hazard by the NIH. Experiments in strontium substitution tend to be successful in gloss type glazes, although there are some effects and colors produced in matte type glazes that can only be obtained through use of barium.