C 0089 (OTTO) Calcium AAS standard solution 1000 mg/L Ca in diluted HNO₃ traceable to NIST - used in the cosmetic industry for color and pigments, as in face make-up, hair dyes or tattoo pigments. Others occur as impurities of the actual ingredient. At high levels, heavy metals show toxicity to humans and may also trigger allergic reactions in the skin.