Total chromium refers to the sum of all chromium species present in a sample, including both trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). Cr(III) is an essential trace element for humans, while Cr(VI) is a known carcinogen. Therefore, it is important to distinguish between total chromium and Cr(III) when assessing the potential health risks associated with chromium exposure.