Which type of pesticide poses the most significant risk to human health if misapplied?

The type of pesticide that poses the most significant risk to human health if misapplied is highly toxic pesticides. This category of pesticides is characterized by its potential to cause severe health effects even at low exposure levels. The toxicity of these substances means that improper application, accidental spills, or unintended exposure can result in acute or chronic health issues ranging from mild symptoms like nausea to more severe reactions, including neurological damage or even death.

While systemic pesticides can carry risks and non-selective herbicides can affect a broad range of plants, the paramount concern with highly toxic pesticides lies in their inherent dangers. Low toxicity pesticides, on the other hand, are generally safer and have a lower likelihood of causing serious health issues, which further distinguishes the highly toxic category as the one that requires the utmost caution in handling and application.