You have probably already heard about the controversy surrounding Genetically Modified Organisms, remembering that they have something to do with the Safe and Accurate Food Labeling Act from a few years back, but let’s review the basics. GMOs are defined by the World Health Organization as organisms whose DNA has been altered in a non-natural way. So why exactly do we use GM crops? Because scientists can manipulate genes to create plants that are insect- and virus-resistant, as well as herbicide-tolerant, therefore creating stronger and resilient crops that will increase output and last longer. And while this may sound good in theory, in reality this industry has grown wildly out of control.

Genetically Modified (GM) crops are relatively new to the agricultural scene, and so there is no long-term study or consensus among scientists on whether these GM foods are fit for human consumption, despite the beneficial claims coming from large-scale industry. Instead, we are hearing from a growing body of evidence—both scientific and anecdotal—that indicates how unsafe GMOs really are for the environment, animals and humans. And we as Americans should be especially concerned, considering that GMOs make up 70-80% of the foods we eat, so here’s what you need to know:

GMOs Increase Herbicide Use

When Monsanto first introduced its Roundup Ready crops, the company claimed that farmers would be able to use less herbicides and avoid plowing, since these glyphosate-tolerant crops would be able to withstand Roundup, unlike the weeds in their fields. However, Mother Nature is a resilient force, and after two decades, we have witnessed weed species rapidly evolving to become resistant to glyphosate. This, in turn, means that not only do we now have super weeds, but more spraying and more concentrated Monsanto-produced chemicals must be used to combat these weeds. In fact, herbicide use could double within the next decade, finding its way into your gut, soils and water tables. In no way is this never-ending battle sustainable.

GM Crops Hurt the Environment

While chemical pesticides and herbicides are created to target GM plants, the reality is that they are also toxic to other organisms, such as bees, butterflies and birds. The recent decline of the honeybee has been partly attributed to the increased use of GM crops and their affiliated sprays. And the Monarch butterfly’s numbers have declined due to the use of harmful chemicals, which have destroyed milkweed plants, the main food source for Monarch caterpillars.

Furthermore, because GM crops are resistant to modern agricultural techniques, they can easily become invasive, drastically affecting delicate ecosystems. GM crops are also typically planted as monocultures, which harm soils by depriving the land of nutrients, and they hurt the surrounding biodiversity due to the decrease in flowers available for pollinators.

GMOs Negatively Affect Your Health

High use of pesticides and herbicides that are used on GM crops have serious health ramifications for those living in rural areas. Required safety precautions are rarely heeded, resulting in spraying near homes and schools, as well as increased exposure for workers doing the spraying. It is incredibly disconcerting that the World Health Organization’s International Agency for Research on Cancer (IARC) issued a report classifying glyphosate as a probable human carcinogen. In addition, Monsanto pesticides are related to birth defects and brain defects.

Meanwhile, we don’t yet know how these genetically altered plants will affect us and our own genes after years of eating them. There is a growing general concern among the scientific community that Roundup has endocrine-disrupting effects—not to mention the increased chronic illnesses, food allergies and digestive disorders that have increased over time since the introduction of GMOs.

Big GM Crop Companies Are Not Pro-Farmer

When large-scale farms use GM seeds, these seeds are not contained and can naturally travel to neighboring farms, carried by wind or blown off a truck. This means that these seeds can contaminate organic farms, which can result in economic loss to these farmers trying to adhere to organic regulations. Monsanto also has a history of suing farmers for using their patented seeds—accidentally or not—without permission, which puts these smaller farms at huge risk.

And if farmers don’t adhere to Monsanto’s strict regulations, and save seeds, expose issues with these GMOs or find legal recourse for their declining health, they can face serious consequences from this giant. Many farmers have lost their livelihoods because they cannot afford to fight this corporate machine.

While pro-GMO companies often claim that their GM crops are going to feed the world, the truth is that such farming practices are not healthy or sustainable. Instead, it’s about time we loudly said no to GMOs, and took our money elsewhere.