Which of the following statements is true regarding the toxicity of natural gas and propane?

The statement that both natural gas and propane are non-toxic is accurate because, in typical usage scenarios, neither of these fuels poses a direct toxicity risk to human health under normal conditions. Both natural gas, which is primarily composed of methane, and propane are considered to have low-toxicity profiles. They are not toxic when combusted properly. However, in the case of incomplete combustion or leaks, both can displace oxygen and present safety hazards like suffocation or explosion, but that is primarily a concern of flammability rather than direct toxicity.

In contrast to this, while both fuels can pose risks associated with improper handling or use, their fundamental chemical properties do not classify them as toxic substances in the manner that many industrial chemicals might be. Therefore, the accurate understanding of their characteristics, primarily focusing on toxicity, supports the conclusion that they are generally non-toxic.