Which of the following is NOT considered a hazardous substance commonly used in embalming fluids?

Hydrogen hydroxide, commonly known as water, is not considered a hazardous substance used in embalming fluids. It is essential to the embalming process primarily as a solvent or carrier for other chemicals. In contrast, formaldehyde, phenol, and methanol are recognized for their hazardous properties. Formaldehyde is a key ingredient in embalming fluids due to its effectiveness as a preservative, but it is also associated with health risks, including respiratory issues and carcinogenic effects. Phenol is used for its antiseptic properties but is also toxic and corrosive in certain concentrations. Methanol serves as an antifreeze agent in embalmings but poses significant health risks if inhaled or ingested. Therefore, given the context of the other options, hydrogen hydroxide stands out as safe and non-hazardous in the realm of embalming practices.