What is one common chemical used in urine preservation that is toxic?

Formalin is a solution of formaldehyde and water commonly used in laboratories for the preservation of biological specimens, including urine. It functions effectively in maintaining the integrity of samples by preventing the growth of bacteria and other microorganisms, which might otherwise degrade the sample. However, it's important to recognize that formaldehyde is a toxic substance that can cause harm to humans upon exposure through inhalation, ingestion, or skin contact. Its use necessitates careful handling and appropriate safety precautions to mitigate the associated health risks.

In contrast, refrigeration is a common and non-toxic method for urine preservation that slows down bacterial growth without introducing harmful chemicals. Sodium benzoate is a preservative that is generally regarded as safe in small quantities, and boric acid, while used for preservation, is less toxic compared to formalin but still requires cautious use. This distinction highlights why formalin is recognized specifically for its toxic properties within the context of urine preservation.