43+ Side Effects Of Pesticides On Humans PNG . A low level of exposure to a very toxic pesticide may be no more dangerous than a high. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, because they are sprayed or spread across entire agricultural fields. Pesticides Human Health Californians For Pesticide Reform from www.pesticidereform.org Toxic to humans impact on environment and ecosystems. Pesticides cause a number of severe health effects and illnesses, ranging from respiratory problems, such as asthma, to cancer. Pesticides can be toxic to humans and lower animals. Experts broadly classify the effects of pesticides as topical or systemic. Toxic to humans impact on environment and ecosystems. Effects of pesticides on human healthpesticides can be classified based on the target groups on which they are designed to act such a...