Which type of diesel engine coolant is considered potentially the most harmful to humans?

The correct answer is ethylene glycol (EG), which is known to be potentially the most harmful type of diesel engine coolant to humans. Ethylene glycol is a colorless and odorless liquid that can be found in many antifreeze formulations. It is highly toxic if ingested, and even a small amount can cause severe health issues such as kidney damage, neurological effects, or even death if not treated promptly.

Ethylene glycol's toxicity is particularly concerning because it has a sweet taste, which can attract children and pets, making accidental ingestion a real danger. In contrast, propylene glycol (PG), while still potentially harmful in large amounts, is generally recognized as much safer for human exposure and is often used in food and pharmaceutical applications. Water-based engine coolants (WEC) and extended life coolants (ELC) also do not exhibit the same level of acute toxicity as ethylene glycol. Therefore, understanding the differences in coolant formulations and their health implications is crucial for safe handling and prevention of accidental poisonings.