Environmental Protection Agency (EPA) Lead Risk Assessor Practice Exam

What does 5000 ppm equate to?

1. 1.0 mg/cm²

2. 0.5% by weight

3. 5000 µg/g

4. both A and B

The correct answer is: 0.5% by weight

The value of 5000 ppm (parts per million) is commonly understood to be a measurement of concentration. In terms of weight, it indicates that there are 5000 parts of a substance per million parts of a total solution or mixture. When converting ppm to a percentage, the relationship dictates that 10,000 ppm is equivalent to 1% by weight. Thus, 5000 ppm can be calculated to be 0.5% by weight. In practical applications, this means that if you have a mixture where the concentration is 5000 ppm of a certain substance, it translates to 0.5 grams of that substance in one kilogram of the total mixture. This understanding is crucial, especially for regulatory compliance and health risk assessments involving contaminants like lead. Hence, the correct interpretation of 5000 ppm as 0.5% by weight aligns with the standard practices used in environmental risk assessments. This makes that particular answer a clear representation of the relationship between ppm and percentage weight.