Initial Publication Date: December 13, 2012

Health Effects of Pesticides in The Great Lakes

Author: Libby Clifford

This case study is part of a collection of pages developed by students in the 2012 introductory-level Geology and Human Health course in the Department of Earth Sciences, Montana State University. Learn more about this project.

The use of pesticides was not as common 10,000 years ago as it is today. Around 1945 "pesticides became common in most areas of the world" (W.R. Carlile). Pesticides are used to prevent unwanted pest (living organisms that occur where they are NOT wanted or cause damage to crops, or humans, or animals). Pesticides are hazardous chemicals that help destroy pest but are putting are environment at risk.

Introduction Pesticides

Pesticides can contain a variety of toxic chemicals. These chemicals can benefit our society and can also be very harmful too. Historically, pesticides have been extremely useful to society. Pesticides can prevent harmful diseases and help kill pests from farmed crops suffering. Pesticides have been known to causing harm to humans, animals, and the environment. The toxic pollutants that are harming the Great Lakes are human-made organic chemicals, also known as pesticides.

Here is a great link that provides an inventory of Toxic substances in the Great Lakes.

Sources of Pesticides

The primary reason for water pollution in the Great Lake is due to the use of pesticides in the agricultural areas. A large percentage of all of pollution in the United States comes from nonpoint source pollution. The source of pesticides in the Great Lakes is called a nonpoint sources (NPS) pollution. Can refers to either water or air pollution. NPS source water pollution is more common in the Great Lakes. The pollution from the pesticides are caused due to the agricultural areas around the Great Lakes.

How Pesticides Travel Into The Great Lakes

The NSP pollution is transported into the Great Lakes when water from rainfall, snowmelt or irrigation runs through the ground into the soil that was exposed to pesticides. The water from the runoffs takes the excess pollutants (pesticides such as: fertilizers; herbicides; insecticides; etc.) lead the pollutants directly into the Great Lakes. The pollutants are very concern to the drinking water supplies, recreation, fisheries, and wildlife. "Many toxic substances tend to bioaccumulate as they pass up the food chain in the aquatic ecosystem" (

Bioavailability of Pesticides in The Great Lakes

The food chain in the Great Lakes is very simple: small fish and zooplankton eat cast quantities of phytoplankton, and the top predators (Lake Trout, Large Salmon, and Fish-Eating Gulls) eat smaller organisms. Do to how the food chain works the toxic chemicals from the pesticides will travel amoung the aquatic food chain.

Here is a great link on the Great Lakes food chain from the EPA Great Lakes Atlas.

Impacts of Pesticides on Human Health

The exposure of pesticides can be a hazard for human. The more exposure to toxic chemicals the less risk. "The highest levels of pesticide exposure are found in farm workers, pesticide applicators and people who live adjacent to heavily treated agricultural lands" (IPM World Textbook). Each type of pesticide can have different health effects on the human body (below are some examples of health issues).

  • The nervous system.
  • May irritate skin or eyes.
  • Affect hormones or endocrine
  • Can cause carcinogens (cancer)

The affects of your health depends on how exposed they are to the toxic chemicals found in the Great Lakes water supply. People who consume fish from the Great Lakes have a high chance of heath risks. For humans we can protect and minimize are exposure to these toxic chemicals in the Great Lakes.

Prevention of Pesticides

Environmental protection and natural resource agencies are working together in reducing the levels of toxic chemicals within the Great Lakes. They are working to protecting the environment and ecoystem's around the Great Lakes. Both the United States and Canada are working together with cleaning up the Great Lakes. Both countries have created new pollution control laws.

  • The Great Lakes Water Quality Agreement: (1972)

The Great Lakes Water Quality Agreement was signed by both Canada and the USA to reduce phosphorus entering any of the Great Lakes.

To protect yourself from the toxic chemicals in the Great Lakes you can avoid eating any aquatic organisms that come from the Great Lakes, as well as anyother wildlife that may live near by. Look for areas that are safe to swim in.

Recommended Readings

  • Pesticides Selectivity, Health and the Environment: By W.R. Carlile

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