Glyphosate—the most widely applied herbicide worldwide and the controversial main ingredient in Monsanto's star product Roundup—is not just found on corn and soy fields. This pervasive chemical can be detected in everyday foods such as cookies, crackers, ice cream and even our own urine.

In fact, researchers from the University of California San Diego School of Medicine found that human exposure to glyphosate has increased approximately 500 percent since 1994, when Monsanto introduced its genetically modified (GMO) Roundup Ready crops in the United States.

"Our exposure to these chemicals has increased significantly over the years but most people are unaware that they are consuming them through their diet," said Paul J. Mills, PhD, UC San Diego School of Medicine professor of Family Medicine and Public Health and director of the Center of Excellence for Research and Training in Integrative Health.

For the study, published Tuesday in JAMA, the research team analyzed the urine excretion levels of glyphosate and aminomethylphosphonic acid (AMPA) in 100 people from a Southern California community over five clinic visits between 1993 to 1996 and 2014 to 2016. AMPA is one of the primary degradation products of glyphosate.

"The data compares excretion levels of glyphosate and its metabolite aminomethylphosphonic acid in the human body over a 23-year time span, starting in 1993, just before the introduction of genetically modified crops into the United States," Mills explained.

"What we saw was that prior to the introduction of genetically modified foods, very few people had detectable levels of glyphosate. As of 2016, 70 percent of the study cohort had detectable levels."

Of study participants with detectable levels of these chemicals, the mean level of glyphosate increased from 0.203 micrograms per liter in 1993-1996 to 0.449 micrograms per liter in 2014-2016. For AMPA, the mean level increased from 0.168 micrograms per liter in 1993-1996 to 0.401 micrograms per liter in 2014 to 2016.

The controversy surrounding glyphosate started in 2015 when the World Health Organization's cancer assessment arm classified glyphosate as "probably carcinogenic to humans." California also listed glyphosate as a carcinogen in July. And just yesterday, the European Parliament, representing 28 countries and more than 500 million people, voted in support of phasing out glyphosate over the next five years and immediately banning its use in households.

Monsanto has adamantly defended the safety of its product and denies it causes cancer. The U.S. Environmental Protection Agency (EPA) also considers it safe for use. Europe's food safety authority (EFSA) also concluded that glyphosate does not cause cancer.

The researchers did not study the health outcomes of the participants but Mills and his colleagues are planning several follow-up studies, according to Consumer Reports.

Additionally, Consumer Reports noted that the concentrations that the researchers measured were far below the EPA's daily exposure limit of 1.75 mg/kg and the European Union's limit of 0.3 mg/kg.

However, experts are concerned about this increasing glyphosate exposure. As Jennifer Sass, Natural Resources Defense Council Senior Scientist, wrote:

"Unfortunately, it is difficult to know what these levels in our bodies mean for our health risks, since the US Environmental Protection Agency (EPA) has failed to conduct a proper risk assessment for glyphosate that includes the aggregate of all our glyphosate exposures—as required by law—from food, drinking water, and residential uses of the herbicide. Even worse—federal agencies don't even know how much glyphosate is in our food and drinking water because glyphosate has never been included in the federal pesticide residue testing program. This is completely outrageous given that it is used at approximately 300 billion pounds annually in U.S. agriculture, including on food crops like corn and soybeans. The US Food and Drug Administration (FDA) has only recently started to test for residues of glyphosate in common foods, and only after tremendous public pressure."

Monsanto has also come under heavy scrutiny over reports that EFSA lifted text from the company's glyphosate renewal application. Documents also suggest Monsanto employees had ghostwritten safety reviews to cover up glyphosate's health risks. The agritech giant is facing more than 250 lawsuits from plaintiffs alleging that they or their loved ones developed non-Hodgkin lymphoma due to exposure to Roundup.

Mills recommended more studies on the human health impact on the increasing exposure to glyphosate from food.

“The public needs to be better informed of the potential risks of the numerous herbicides sprayed onto our food supply so that we can make educated decisions on when we need to reduce or eliminate exposure to potentially harmful compounds," he said.