Cr 3+ or trivalent chromium is a naturally occurring chemical found in soil. Cr 6+ or hexavalent chromium is a byproduct of man-made chemical processes.
US EPA has set the total chromium maximum contaminant level at 0.10 mg/L. World Health Organization (WHO) guideline is 0.05 mg/L.
California has the same standard for total chromium as WHO but has a stricter enforceable standard for hexavalent chromium, set at 0.01 mg/L.
Potential health effects of hexavalent chromium include kidney and liver damage, reproductive problems and allergic reactions.