Close It's a smart idea to become mindful of these products and take measures to eradicate them wherever possible, but health and wellbeing aren't just about food and exercise. It's also about minimizing exposure to dangerous products. A harmful substance is one that has the potential to be dangerous or has negative health effects. People are usually nervous about chemicals collected at hazardous waste facilities, such as polychlorinated biphenyls (PCBs) and dioxin. Household chemicals, prescription, and over-the-counter medications, gasoline, alcohol, poisons, cooking oil, and cosmetics are only a few examples of harmful products. In such circumstances, any chemical may be poisonous or dangerous.