Think Twice about those Pesticides. By Julie Peller, Ph.D.

In many neighborhoods, a springtime ritual involves adding pesticides to lawns that kill or prevent the growth of unwanted plants, or weeds. An estimated 80-90 million pounds are applied to lawns in the United States each year. The product Roundup is a very common chemical herbicide. Its original formulation contained the active ingredient glyphosate, which is still used for agricultural and commercial purposes. Now, the Roundup formulation sold for residential use contains different herbicides. Over the years, 18 billion pounds of glyphosate have been applied to fields and lawns, despite strong evidence of its toxicity.

In March 2026, scientists from North America and Europe gathered at a symposium on glyphosate to evaluate the research from the last decade. They determined that the evidence that glyphosate is harmful to human health “is now so strong that no additional delays in regulation of glyphosate can be justified.” Another analysis by Dr. Bruce Lanphear at Simon Fraser University explains that formulations used in land applications differ from the pure samples used to study toxicity. “Farmers and landscapers do not spray pure glyphosate. They spray Roundup, a mixture containing surfactants designed to drive glyphosate through plant tissue. Those same surfactants can also enhance absorption through human skin. Regulators were evaluating the molecule. Workers were exposed to the mixture.”

It is difficult to conduct studies that evaluate real-world chemical exposures, especially those that involve long-term (years) exposures. An experiment exposing rats to glyphosate herbicides, conducted by researchers at the Ramazzini Institute in Italy, was designed to mimic real-world, longer-term exposures. The exposed rats showed increased rates of leukemia and other cancers, and these often appeared early in life. Many people have been exposed to glyphosate. Numerous lawsuits have been filed, and the company manufacturing Roundup, Bayer, has paid out more than $10 billion to settle approximately 100,000 Roundup claims.

Products like Roundup, which contain chemicals designed to kill pests, should be used sparingly. The product labels do not effectively inform the public about the true dangers of the chemicals. We can spread the word that “perfect lawns” are not natural. The chemicals used for a weed-free lawn can be harmful to the environment and human health.

Julie Peller, Ph.D., is an environmental chemist (Professor of Chemistry at Valparaiso University). She has been writing a weekly column, The Green Junction, for the past seven years and is helping to move the call of Laudato Si to action. Her research interests include advanced oxidation for aqueous solutions, water quality analyses, emerging contaminants, air quality analyses, challenges along the Lake Michigan shoreline (such as Cladophora, water, and sediment contaminants), and student and citizen participation in environmental work.