Some of the characteristics are acidity, depth, temperature, clarity, flow rate, presence of biological organisms and general chemistry. Living organisms accumulate certain pesticides. Through the process of bioaccumulation, pesticides accumulate in lower organisms and are passed to higher organisms in the food chain when eaten. The higher organism will accumulate the pesticides at higher levels than their food source. Pesticide levels in fish, for example, can be tens to hundreds of thousands of times greater than ambient water levels in which they live.
Humans are at the top of the food chain.
They bioaccumulate the pesticides accumulated by the lower animals and plants that they eat. It is not only fish but also domestic farm animals and plant food which can accumulate pesticides. Care must be used in the use of pesticides in agricultural as well as home and garden scenarios. A study of indoor air quality by EPA in 1990 detected 26 pesticides. DEET can cause central nervous system disturbances, dermatitis, and skin irritation.