What concentration level of penta is considered safe for exposure?

The concentration level of penta that is considered safe for exposure is a few parts per billion. This level is significantly lower than the other options, which indicates that it represents a minimal risk to health when exposure occurs. The reason for establishing this low threshold is due to the potential toxicity of penta, particularly its effects on aquatic life and human health. Since penta is a chemical used in wood preservation and can leach into the environment, maintaining exposure at such low levels helps to mitigate these risks. The safety limits reflect a balance between the use of penta for wood protection and the need to protect human and environmental health from its potential harmful effects. Lower concentration thresholds reduce the likelihood of negative health impacts, making this choice the safest option.