When disposing of an old chemical, which option is least preferable?

When considering the disposal of old chemicals, the least preferable option is throwing it away. This method often leads to improper disposal, which can have serious environmental consequences. Disposing of chemicals in general waste may result in contamination of soil and water sources, hazards to human health, and violation of local regulations concerning hazardous waste.

In contrast, recycling allows materials to be repurposed for new applications, minimizing waste and resource consumption. Using the chemical safely, if still viable, is preferable as it reduces the need for disposal entirely by taking advantage of the product's intended purpose. Donating chemicals to organizations that can utilize them safely is also a positive alternative, as it promotes sustainability and safety in handling hazardous materials while avoiding waste. Each of these options aims to minimize environmental impact, making throwing it away the least responsible choice.