What's the risk? Pesticide residues

In this series, we look at common products and ingredients we use throughout the spring and summer to explore their safety and toxicity. In this post, we take a look at pesticide residues.

What are pesticides?

A pesticide is a broad term used to describe natural and synthetic chemicals (remember, everything is a chemical!) that can harm or kill organisms, including insects, invasive weeds, fungi, rodents, bacteria, and more.

What is a pesticide’s purpose? Are they only used to grow food?

Pesticides have a wide range of purposes. While they are most commonly associated with agricultural use in the prevention of weeds, insects, and more, we also use pesticides in our daily lives.

Disinfectant cleaning products, such as bleach, are pesticides because they kill organisms like bacteria. Home-use insect control products, such as wasp and hornet killers, are also pesticides because they kill insects.
In this post, we’re going to focus on pesticides in agricultural use, but it’s important to note that we safely use pesticides regularly.

How are pesticides used in agricultural situations?

Pesticides are used in conventional and organic farming practices to control harmful insects, fungi, and other pests from causing crop damage.

Organic farming relies on naturally-derived pesticides and some synthetically-derived products like pheromones and other farming practices like crop rotation and limiting monoculture to protect crops (1,2).
Conventional farming relies on synthetically or naturally-derived pesticides and products to ensure crop growth and harvest. As well as other best practices like crop rotation.

Are naturally-derived pesticides safer than synthetically-derived pesticides?

Both naturally-derived and synthetically-derived pesticides must meet the same safety standards.

Any chemical can cause adverse health impacts at specific levels. Remember, deadly arsenic is a natural product that can cause harm, and doctors safely use deadly botulism toxins in patients.

For years, farmers used the naturally-derived pesticide rotenone in organic farming. Researchers later discovered that exposure to this pesticide could cause Parkinson’s Disease-like symptoms, so farmers discontinued its use in agricultural practices. The use of other synthetically-derived pesticides has also been discontinued when they were linked to produce adverse effects, like DDT.

As researchers learn more about pesticides and their toxicological properties, regulations and uses are changed to reflect the latest science. The origin of the pesticide does not determine toxicity.

How are they regulated?

Multiple U.S. federal agencies control pesticide use and allowable residue levels, including the U.S. Environmental Protection Agency (EPA), Agricultural Department (USDA), the Food & Drug Administration (FDA).

The EPA has an established registration process for all pesticides that include in-depth, peer-reviewed risk assessments to measure the impact on human, environmental, and animal life before they are allowed on the market.

Registered pesticides have a chemical and toxicological profile available to the public that includes the amount of residue safely allowed on specific food products.

Regulations are enforced by local, state, and federal government organizations to ensure residues are below allowable levels (1,2).

How much residue is allowed?

Researchers determine the safe level by evaluating the product’s toxicological profile and setting a limit that’s measured in parts per million (ppm).

A part per million is a small measurement representing one part in a whole entity of one million equal parts. For example, 7 drops of water in a 60-gallon bathtub is 1 part per million (ppm).

Ted Ed put together a fantastic video helping to explain parts per million.

It's an even smaller number when we talk about parts per billion (ppb) or parts per trillion (ppt). While billion or trillion sounds like it would be a larger quantity, it is a much small quantity by a much larger magnitude.
For example:
1 ppm = 0.000001 of 1
1 ppb = 0.000000001 of 1
1 ppt = 0.000000000001 of 1

It's essential to keep the actual amount of residue in perspective because while it may sound like a large number, it's minimal when compared to the overall product. While we can strive to get to zero, it’s not feasible with our current technology to have zero pesticide residues, nor is it necessary when we know the safe exposure levels for even the most vulnerable populations.

Let's take a look at glyphosate.  

Glyphosate is a pesticide used to grow and harvest many crops and to kill weeds during the growing season. Sometimes, there can be glyphosate residue left on the food products.

Will this cause us harm? 

Let’s look at grain. Sometimes, glyphosate residue can be found on grain. In one situation, many grain products were tested, and the highest level of glyphosate residue found on the grain products was 2.8 ppm. We know the safe level is 30 ppm based on the EPA’s assessment.We know 2.8 ppm is well below the safe level of 30 ppm, meaning this small amount of glyphosate residue is well below the safety threshold, so it’s safe for us to consume.

What’s the risk?

While we looked at glyphosate as an example, each pesticide will have different safety guidelines and associated hazards and, ultimately, risks.

Current agricultural pesticide use has stabilized food security in many parts of the world for the last 50 years.

Without agricultural pesticides, our crops are vulnerable to pests that destroy crops. With pesticide use, it’s estimated farmers lose between 5%-20% of major grain crops yearly. With warming temperatures impacting the insect population, we could expect to see an additional increase in crop loss over the next 50 years, potentially impacting the global food supply (1,2).

When used properly and within established guidelines and regulations, the current literature shows agricultural pesticide residue found on crops does not adversely impact human health. We also know that we could face greater food insecurity without pesticide use in an agricultural setting.

The benefits of responsible agricultural pesticide use may outweigh the potential risks associated with the pesticides.

Additionally, the small amounts of pesticide residue found on products are well below the established safety threshold to ensure products remain safe for even vulnerable populations to consume.

The good news.  

As technology advances, we continue to learn more about pesticide safety and ways we can improve our agricultural processes. Already drones and other precision technologies are helping farmers better target pesticide use to minimize the amount of pesticides needed and enhance crop yields.

In our next post, we will look at ways you can remove any lingering residual pesticides from your produce.

If you have any questions about foods and ingredients, please reach out to us on Twitter, send us an email, or submit your idea to us at go.msu.edu/cris-idea.

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