Yes, transformer oil is considered hazardous material under certain conditions. While it is primarily derived from mineral oil and can have low toxicity, transformer oil may contain harmful substances such as PCBs (polychlorinated biphenyls) if the oil is older or not properly managed. The environmental and health risks associated with spills or improper disposal can classify transformer oil as hazardous. Therefore, it’s essential to handle, transport, and store transformer oil according to strict regulations and guidelines to minimize any potential hazards.