Incidental sum concentrations of lead, mercury, hexavalent chromium and cadmium must be no greater than how many parts per million in dyes used to color bags?

• A. 10
• B. 50
• C. 100
• D. 500

Answer: (C)

This item tests the safe level of heavy metals in dyes used to color bags for biomedical waste. The rule is that the incidental sum concentrations of lead, mercury, hexavalent chromium, and cadmium in the dye must be no greater than 100 parts per million. In practice, you add up the amounts of each metal present in the dye, and the total must be 100 ppm or less.

For example, if a dye contains 40 ppm lead, 30 ppm cadmium, 20 ppm mercury, and 10 ppm chromium(VI), the sum is 100 ppm, which meets the limit. If the combined total exceeds 100 ppm, the dye would not meet the requirement. This keeps potential toxic metal exposure low if a bag degrades or leaks.

The 100 ppm limit balances practicality in dye formulations with safety, whereas a much lower figure (like 10 or 50) would be unnecessarily restrictive, and a much higher figure (like 500) would allow more heavy metals than the standard intends.