When chemical company, Monsanto, introduced a broad-leaf and grass killing herbicide in 1974, most farmers thought it was a great idea. If you have ever tried growing a garden in regular soil, you will be amazed how quickly whatever you planted becomes totally smothered out by grass and weed seeds you had no idea were in the soil. Weeding can take many hours of labor or you risk a big reduction in crop yield. The introduction of genetically modified crops that were resistant to the killing effects of herbicides allowed farmers to grow crops that were not effected by the weed killer thus completing the circle. Large mono-crop farmers in the US quickly adopted this herbicide resulting in more than 500 million additional pounds, mostly RoundUp®, having been applied. The U.S. Geological Survey studies in 2015 showed RoundUp® was found in our air, rain, streams and surface water.
How does glyphosate work?
It is absorbed through foliage mainly and is transported to growing points. There it inhibits a plant enzyme involved in amino acid synthesis and stops plant growth. This chemical does not work as a pre-emergence weed killer. The next step was to create resistant crops. The first RoundUp® resistant plant developed was a RoundUp Ready Soybean. Soybeans are one of the top four crops traded globally and makes up 65% of the global animal protein feed supply. Resistant crops allow farmers to apply the herbicide to entire crops to kill weeds without destroying the crops. Many regulatory bodies, including the US FDA, originally approved glyphosate and formulations like RoundUp®. Over the years, however, there have been health concerns raised over the use of and exposure to these herbicides.
Health agency evaluations
In 2015, the World Health Organization’s International Agency for Research on Cancer released an evaluation of the carcinogenicity of five organophosphate pesticides and the herbicide glyphosate.
Glyphosate currently has the highest global production volume of all herbicides. The largest use worldwide is in agriculture. It’s agricultural use has increased sharply since the development of crops that have been genetically modified to make them resistant to glyphosate. Glyphosate is also used in forestry, urban, and home applications. Glyphosate has been detected in the air during spraying, in water, and in food. The general population is exposed primarily through residence near sprayed areas, home use, and diet, and the level that has been observed is generally low. It is supposed to only affect plant proteins, but it is being incorporated into food as residue or microbes that live in the intestinal tracts.
The herbicide glyphosate and the insecticides malathion and diazinon were classified as probably carcinogenic to humans (Group 2A). Group 2A means that the agent is probably carcinogenic to humans. This category is used when there is limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals. Limited evidence means that a positive association has been observed between exposure to the agent and cancer but that other explanations for the observations (called chance, bias, or confounding) could not be ruled out. This category is also used when there is limited evidence of carcinogenicity in humans and strong data on how the agent causes cancer. 
The UN agency found glyphosate in farmworker’s blood, urine, chromosomal damage in cells, increased risks of non-Hodgkin lymphoma in some people exposed, and tumor formation in some animal studies. In addition, the state of California has added glyphosate to the list of chemicals known to cause cancer for purposes of Proposition 65 (the safe drinking water and toxic enforcement act of 1986).
Effects on human health
Lots of research and litigation are ongoing around the US regarding the effects to human health of using this herbicide on food crops. Everyone of us should be concerned about the potential harm being done to our food supply system and how it might effect our lives. 
Follow these precautions when using herbicides containing glyphosate:
- Wear goggles to protect your eyes.
- Use a face mask to prevent accidental inhalation.
- Wear long sleeves, long pants and gloves to prevent skin irritation.
- Avoid touching plants that are wet with glyphosate, and wash your hands thoroughly after use.
- Spray on a calm day. Wind can carry the spray to other plants and it increases the chances of human contact.
 IARC Monographs Volume 112: evaluation of five organophosphate insecticides and herbicides.pdf
Billie Nicholson, Editor