A new report from the World Health Organization suggests an ingredient found in Monsanto's weed killer, Roundup, has caused cancer in workers exposed to the chemical.

A co-author of the study, Kate Guyton, stopped short of telling Quartz in an interview that the chemical Glyphosate definitively causes cancer. The study can be seen here.

But her team at the WHO's International Agency for Research on Cancer reviewed the effects of glyphosate on workers in the forestry and agriculture industries.

The study found that an inordinate amount of workers who used the chemical developed lymphoma compared with those who do not.

Monsanto issued a press release in response, refuting the information supplied by the WHO study.  

Several studies published last year by the Institute of Science in Society indicate various cancers and chomosomal damage occurred in lab animals fed maize treated glyphosate.  

One famous study indicates long-term toxicity from Roundup and Roundup-tolerant genetically modified maize, resulting in a range of tumors, kidney failure and death.  

The study is known as the "Seralini Study," based on the work of Gilles-Eric Seralini, a well-regarded French molecular biologist, but the study's proper name is "New analysis of a rat feeding study with a genetically modified maize reveals signs of hepatorenal toxicity."

The Seralini study indicates a dramatic growth in tumors in both male and female lab rats after two years of testing on them GMO maize and water that had a small parts per billion of Roundup added.

In addition, there were chronic kidney deficiencies in the rats, pituitary glands were disabled, sex hormone balance was altered and liver problems presented. In females, death was two to three times higher than in the rats that did not receive the Roundup, and death came prematurely, according to the Seralini study.

Monsanto saw a $994 million profit in 2014 over 2013, according to the company's annual report and reported in Quartz. It attributes the increase to the sales of Roundup and its glyphosate-based weed killers.

Many groups across the nation support the findings of Seralini. Other groups are calling for labeling of food so that consumers can decide on their own if they want to consume genetically modified organisms. 

But Monsanto is running a multi-million publicity and marketing campaign, including TV commercials asking people to go to the Monsanto website to get "involved in the conversation."

However, most of the questions on the website - allegedly posted by concerned consumers - contain misspellings, grammatical errors and punctuation errors and position the questioners to look particularly ill-informed. 

Meanwhile, earlier this month, one of the most outspoken supporters of food labeling, Bill Nye the Science Guy, took a visit to Monsanto headquarters and afterward seemed to take a new stance on the safety of GMO food.

Nye's about-face coincided with a tour of the Monsanto buildings, as reported by EcoWatch.

Mother Jones magazine also noted the change of heart by the Science Guy, who influences millions of children and their parents through his media efforts. 

Nye's book published last year, "Undeniable: Evolution and the Science of Creation," calls for labeling and care for the earth.  

But since his visit to Monsanto, Nye told Bill Maher he was revising the section of his book after spending time with the scientists at Monsanto, according to Mother Jones.

"I have revised my outlook and am very excited about telling the world," he told Maher.  "When you're in love, you want to tell the world!"