Ingredient Roundup

This Roundup ingredient could cause cancer, but the EPA won’t ban it

In July, chemical-manufacturing giant Bayer announced that home gardeners would no longer be able to buy products containing glyphosate, the active ingredient in the world’s most actively used weed-killer Roundup. It was the culmination of tens of thousands of lawsuits filed against Bayer and Roundup’s previous owner, Monsanto, for their alleged role in causing a…

In July, chemical-manufacturing giant Bayer announced that home gardeners would no longer be able to buy products containing glyphosate, the active ingredient in the world’s most actively used weed-killer Roundup. This was the culmination tens of thousands of lawsuits against Bayer and Roundup, Monsanto’s former owner for their alleged involvement in the development of a type of cancer called non-Hodgkin’s lymphoma. have been awarded hundreds of millions to plaintiffs. Bayer filed an petition to have one of these cases reviewed by the US Supreme Court in August.

The decision to remove glyphosate from the home-gardening market wasn’t an admission of culpability, and farmers will still use glyphosate-containing products. Bayer maintains that glyphosate is safe and doesn’t cause cancer. The most recent report from 2016 by the Environmental Protection Agency (EPA) supports Bayer’s view. The authors of the report concluded that glyphosate was an unlikely carcinogen and poses no known meaningful risks to human health.

At the same time, scientists and economists raise doubts about the safety of Roundup and similar products–and the rigor of the research that’s gone into reports by Bayer and the EPA.

How Roundup became ubiquitous

When Monsanto first marketed Roundup in 1974, the company sold it as a breakthrough tool for agriculture: an herbicide that was safe for the environment and for humans. Unlike the pesticide DDT, which was banned by the EPA in 1972, Monsanto asserted that glyphosate wouldn’t linger in the environment or in human bodies. Studies suggest that within soil, glyphosate’s half-life, or the amount of time it takes for half of a particular application to break down, is between seven and 60 days. AMPA is a chemical byproduct. However, neither glyphosate or AMPA are likely to accumulate in human cells. Instead, they’re excreted in urine and feces.

[Related: Pesticides might be worse for bees than we thought.]

Glyphosate also kills weeds by inducing the shikimate pathway. This is a way that plants use to make energy. It does this by blocking an enzyme that aids them to synthesize amino acid from carbohydrates. In essence, glyphosate starves plants. This pathway is not available in human cells. This distinction sets glyphosate apart among other chemicals that cause cancer and genetic mutations. These chemicals tend to target pathways also found in human cells. Jia Chen is a professor of environment and public health at the Icahn school of medicine at Mount Sinai. Chen states that glyphosate is considered harmless for this purpose.

While human cells don’t use the shikimate pathway to communicate with each other, bacteria does. It is possible that glyphosate’s risk to human health may be due to its effect on good bacteria in our guts. These good bacteria are vital for our immune system and help us to digest our food.

Studies on rats and bacteria cultured in labs suggest that glyphosate inhibits the composition of gut bacteria, possibly limiting their ability to modulate our immune systems. These studies don’t prove that glyphosate has the same effect inside the body. These effects don’t need to be sustained in cells; the chemical must simply pass through. Inflammation can be caused by imbalances in the microbiome. Researchers reason that both inflammation and immune-disruption are associated with increased cancer risk, according to a 2018 review published in the journal Carcinogenesis. On top of that, research suggests that even at very low concentrations, glyphosate mimics human hormones, potentially triggering or speeding up the growth of tumors.

Nearly 50 years after its introduction to agriculture, the chemical remains ubiquitous in the world. “Glyphosate is, by far, the most heavily used and most profitable herbicide ever discovered,” says Charles Benbrook, an agricultural economist at the Heartland Health Research Alliance and an expert witness in the ongoing Roundup litigation. As of 2014, 825,000 tons of the herbicide were used each year worldwide, according to an article published in the journal Environmental Health.

Scientists have found glyphosate everywhere from tree roots to honeybee hives. In a study of 94 pregnant women who weren’t directly exposed to herbicides at work, Chen and a team of international scientists found traces of glyphosate in the urine of 95 percent of participants. “You can even detect it in surface water and rain,” Chen says, “Glyphosate is basically everywhere.”

The trouble with studying Roundup

Scientists have linked glyphosate and glyphosate-containing products to a number of conditions, from miscarriages to cancer. However, you cannot randomly expose people to potential toxins and compare them with an unexposed group. This would be illegal for the former, and would make it difficult for the latter to conduct clinical trials for drugs. Chen states that it is still challenging to examine the effects of glyphosate on humans. Scientists are more inclined to examine the effects of the chemical in human cells or on other animals in the laboratory, or to ask people about their exposure to glyphosate to determine if there are any health correlations. However, lab mice exposed to toxic chemicals won’t provide a clear picture of human health. People may encounter other potentially harmful substances throughout their lives. So, in other words, neither approach is perfect.

In 2016, the EPA concluded that glyphosate was “not likely to be carcinogenic to humans.”

[Related: Pesticides can hurt agricultural communities—so why do farmers fight back against bans?]

Scientists and regulators as well as the general public have focused heavily on the connection between glyphosate use and cancer. “But from my perspective, I’m more concerned with the non-cancerous outcomes. Chen states that health is more than cancer. This year, Chen’s pilot study on pregnant women, published in the journal Environmental Pollution, linked higher urinary concentrations of glyphosate to shorter pregnancies. All of the pregnant people in the study gave birth to full-term babies–in other words, gestation lasted 37 weeks or longer–but shorter pregnancies, especially those shorter than 37 weeks, are associated with complications in newborns, from breathing to gastrointestinal problems. Babies born to women who had higher levels of glyphosate were also more likely to have a greater distance between their anus (and genitalia) than those born to women with lower levels. This is due to higher levels in male sex hormones. Chen was alarmed by this finding, but it is not conclusive.

Data about non-cancer outcomes aren’t all that we have, according to Leland Glenna (sociologist at Pennsylvania State University). Scientists don’t know what Roundup is, because herbicide producers aren’t required by law to disclose the active ingredients in their products. This makes it hard to study.

The data is not just incomplete. Glenna, who studies the role of science in agricultural policy-making, thinks that much of it is not reliable. Much of the epidemiological dat

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