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How Bioaccumulation and Biomagnification of Pollutants Affects Our Food Supply

Chris has a Master's degree in engineering and uses his knowledge to write about a variety of topics from an analytical perspective.

Learn how chemicals in the environment are affecting our food supply and what you can do to protect yourself.

Learn how chemicals in the environment are affecting our food supply and what you can do to protect yourself.

What Is Bioaccumulation and Biomagnification?

When pollutants (such as those found in contaminated stormwater runoff) enter the food chain faster than they leave it, we can say that they have been bioaccumulated. Bioaccumulation problems are associated with high or frequent exposures to toxic chemicals in the environment. These contaminants can be anything from pesticides and fertilizers to industrial manufacturing effluent and air pollution.

An example of bioaccumulation could be when an animal drinks polluted water or breaths tainted air. These toxic chemicals in the air and water enter the animal’s body at a higher dose than what is normally expected to occur in an everyday setting. This can either kill or injure the animal and sets the stage for residual contamination and future biomagnification to occur.

Biomagnification occurs when the concentrations of the toxic substances increase as they move upward through the food chain. Biomagnification can only happen when the chemicals are fat soluble, have a long lifespan, and are biologically active (reactive to organic matter). What this means is that a small or normally insignificant amount of a contaminant in the environment can slowly collect inside of an organism and eventually grow to concentration that could cause great harm to it.

The concentration of a toxic chemical is magnified as it moves upward through the food chain.

The concentration of a toxic chemical is magnified as it moves upward through the food chain.

Mercury in Tuna Fish: An Example of Biomagnification

A perfect example of biomagnification is the mercury that is sometimes found in tuna fish. The concentration of mercury in the environment in which the fish resides is extremely low. However, its concentration is magnified as it moves upward through the food chain. Over the lifespan of the tuna, the concentration of mercury in its body has slowly increased to levels that may potentially be harmful to humans.

DDT Concentration in the Food Chain

DDT Concentration in the Food Chain

DDT: An Example of Biomagnification

Another great example of chemical biomagnification is the story of the insecticide DDT. This chemical was made popular in the early 1940’s by its success in controlling mosquitoes. By the 1960’s, biomagnification of DDT had occurred to such a degree that bird populations (including the bald eagle) were beginning to suffer. The concentration of DDT was found to have had an overall increase of more than 500,000 times going from the minute amount used to protect crops to the top of the food chain. Eventually, the use of DDT was banned in the United States in 1972. Many of bird species that were affected by this chemical have since made a considerable recovery.

Contaminated Foods All Around Us (Why Bioaccumulation and Biomagnification Is Bad)

Now that we know what bioaccumulation and biomagnification is, let's discuss this in terms of our food supply. Farmers use a variety of chemical pesticides to control insects and other pests that can damage their crops. The pesticides help improve growing efficiencies by increasing the amount of food that can be produced from a field. The major downside to these chemicals is that they can be harmful to humans if consumed in high enough concentrations or doses. Fear of adverse health affects caused by pesticide contamination is one reason why the organic food movement was created.

Always wash your fruits and vegetables before you eat or cook them.

Always wash your fruits and vegetables before you eat or cook them.

How Pesticides Can Affect Your Food

Many of these pesticides are essentially harmless when a human is exposed to a single dose of residual chemical that is left on a fruit or vegetable. However, when the exposures to the chemical occur on a frequent basis, some pesticides can be bioaccumulated within our bodies. Over a long period of time, adverse health affects such as cancer can be created by the increased concentrations of these substances within our own bodies. Besides bacteria, this is the major reason that you must always wash your produce (in fact, you should always wash your Organic produce as well just to be safe).

Pesticides can also be leeched into the environment by stormwater runoff from farm fields. The chemicals can then easily become absorbed into plants and consumed by game wildlife and farm animals. The result is the biomagnification of the pesticide within the food chain. We can then later become exposed to the toxic pesticides when we eat the meat from these contaminated animals.

The Environmental Protection Agency does have strict regulations on the use of pesticides, though they have little control over produce grown outside of the US. In addition to this, the EPA and several private companies have already tested many of these chemicals to determine what the adverse health affects of over exposure is and if they can be bioaccumulated. Unfortunately though, there is plenty of work yet to be completed. There are literally thousands of chemicals that still require testing. Experiments with these substances are often very expensive and time consuming.

How to Protect Yourself

Buy Organic: Buying organic produce is probably one of the best ways to protect yourself from the adverse health impacts of pesticides.

Buy Local (or Grow Your Own): If organic produce is not an option, or if it is just too much for your budget, try to buy locally grown fruits and vegetables instead. Better yet, try growing a garden of your own!

Use Pesticide Alternatives: Remember, there are many natural or chemical-free alternatives to pesticides that you can use to stop pests from eating your food. For example, the state of New Jersey has a great document on safe and natural alternatives to pesticides (see resources below).

Wash Your Produce: And lastly, don't forget to thoroughly wash all of your produce (and your hands) before consuming or cooking them.

Pesticides for Lunch Anyone?

Pesticides for Lunch Anyone?

References and Resources

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2011 Christopher Wanamaker


Nirmal Vikas on May 05, 2014:


This is very helpful to complete my Biology project

Kathy on March 01, 2012:


Christopher Wanamaker (author) from Arizona on August 10, 2011:

Prasetio30 - Thanks for the positive feedback. If anything, people need to know that washing their produce is very important.

Simone Smith - The more people that know about this, the better. Maybe someday the knowledge can instigate changes to improve the protection of the public.

Jetta17 - It's unfortunate that mercury poisoning is even an issue. I used to work at a nutritional supply store and people with mercury poisoning came in often to discuss it's causes and treatment possibilities. It was a sad situation indeed.

Mirkalim - Thank you for the comment. I can't stress how important this issue really is.

mirkalim on August 09, 2011:

Great job you have highlighted one of the potential dangers in produces that we eat regularly but do not know the hazards due to the chemical sprayed on them which are codswallop by us.

jetta17 on August 09, 2011:

Very nice informative hub. This is exactly what I've been taught for years in Biology. Here in Colorado, there are a few bodies of water along the front range where old mines are leaking contaminants such as mercury and uranium. There are concerns over eating Walleye over 24" long because of the potential for mercury accumulation. It's never top news, but something that people must definitely be aware of.

Simone Haruko Smith from San Francisco on August 02, 2011:

My middle school discovery of bioaccumulation and biomagnification has stuck with me for years- it's one of the few lessons that I still keep passing on to people! I'm glad to see you spreading the word too, CWanamaker! Great Hub.

prasetio30 from malang-indonesia on July 30, 2011:

I had never knew about this. Thanks for writing this. I learn much from you. I'll share this with my friend. As a teacher, I got a new lesson from you. Vote up again...


Christopher Wanamaker (author) from Arizona on July 28, 2011:

Robin - Most produce cleaners will work at least as good as water does for cleaning fruits and veggies. Most of what I have read about them is positive. They are effective at removing pesticides, waxes, and some bacteria just like water is. A couple of sources said that they don't clean any better than water does at all. Personally, I just use lots of cold water. I rinse the produce for at least a minute and gently 'scrub' them with my hands (clean hands of course!). Mushrooms are tough to clean though. Too much water and they just fall apart. I quickly rinse those and then lightly pat them with a damp towel.

br4d33nn from Peekskill on July 28, 2011:

what the.. what is that???

Robin Edmondson from San Francisco on July 28, 2011:

Very interesting! We have bought vegetable and fruit cleaner from Trader Joe's that apparently removes pesticides. I use this whenever I can't find organic produce. Do you know if this is a valuable alternative? Also, I would be greatly interested to read a Hub about the risks of grilling foods as we eat a lot of BBQ. Cheers!

Christopher Wanamaker (author) from Arizona on July 28, 2011:

ChristinS - Unfortunately, most people don't think about it until its too late. Long term exposure to harmful pesticides is one of the causes of cancer. People just need to be aware and informed so they can take action to protect themselves.

Christin Sander from Midwest on July 28, 2011:

Very good and informative hub. I truly believe we should all be more concerned about what goes into our mouths. Most of us probably don't consider the toxic buildup that occurs over time.

Christopher Wanamaker (author) from Arizona on July 28, 2011:

Oh, I also wanted to add that there is a risk of infections caused by eating organic foods especially because there are no pesticides to control the bacteria. Always wash your produce!

Christopher Wanamaker (author) from Arizona on July 28, 2011:

You are correct Larry. Bacteria on foods is indeed a major concern. In fact, I would say that it is probably more of a concern than pesticides are. That, as well as the risks of grilling food, will be for another hub someday. Thanks for reading.

Larry Fields from Northern California on July 28, 2011:

CWanamaker, you've done a good job in laying out some of the salient facts, without crossing the line into Scare-of-the-Month-Club territory. However some organic agricultural practices carry risks of their own. Just as there's no such thing as a free lunch, there are no risk-free lunches either.

Example. My understanding is that the recent E coli outbreak, which killed some people in Europe, was linked to bean sprouts, which had been contaminated with fecal matter in the 'organic' fertilizer that was used to replace nasty, evil 'chemical' fertilizers.

Risks and benefits need to be quantitated and balanced. By far, the greatest risks in domestically produced food stem from contamination with mold, bacteria, and other microscopic beasties.

My choice for big food risk number 2: the carcinogenic heterocyclic amines. These chemicals are produced when beef is cooked directly over open flames or charcoal. The protein in the juice that drips down onto the flames is denatured into HCAs, which in turn is vaporized, and then deposited onto the meat. Boiling, sauteeing, and microwaving are much safer ways of cooking beef.

A good book for a quantitative perspective on similar issues is Technological Risk.

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