Which one of the following is not a major source of human exposure to dioxin?

Dioxins are a group of chemically related compounds that are persistent environmental pollutants. They primarily enter the human body through the food supply, particularly from animal products. Fish, meat, and dairy products are significant sources of dioxins because these compounds bioaccumulate and biomagnify in the fatty tissues of animals.

Water, while it can become contaminated with dioxins, is generally not considered a major pathway for human exposure compared to dietary sources. The levels of dioxins found in water are typically much lower than those found in contaminated food items. Thus, when evaluating the most significant sources of human exposure, water does not rank among the major contributors. This positions water as the correct answer in this context, highlighting its lesser role compared to food sources.