#EcoAdvice from our expert

Dear Dr. Donley,

I’ve read that Roundup weedkiller is safer than table salt, but I’ve also heard it can cause cancer. Clearly both of these can’t be right, so can you explain the discrepancy?

Signed,

In-salted by the Conflicting Information

Dear Tastefully Asked,

The safety of glyphosate, the active ingredient in the Roundup weedkiller, has been compared to many things over the years, but the table salt comparison stands out as particularly ridiculous. In fact the state of New York took legal action against Monsanto for false advertising for making this very claim. Monsanto agreed to cease and desist from making this claim, but it is still commonly parroted by aggressive supporters of GMOs and chemical company apologists.

So where did this claim come from? The basis of this claim lies in a measure called the LD50 (which means “lethal dose, 50 percent”). The LD50 is the concentration of a chemical needed to kill half of the people or animals that are exposed — a measure of how immediately toxic a chemical is. Substances like snake venom and arsenic have a very low LD50, while substances that are less acutely toxic will have higher LD50 concentrations.

Table salt does, in fact, have a lower LD50 value than glyphosate, meaning it takes less salt to immediately kill you. The LD50 values indicate that a 150-pound person would need to orally ingest a half a pound of salt, or nearly a pound of glyphosate, in order to die from their incredibly ill-advised binge. Honestly, eating a half a pound of salt in one sitting seems more akin to an impossible dare — an eating-contest stunt worthy of Kobayashi or Cool Hand Luke — than something a sane person would actually do.

Suffice it to say that no one’s going to intentionally ingest enough salt or glyphosate to immediately die from their exposure, and comparing the LD50 values of chemicals that can have serious health harms other than immediate mortality is so misleading as to be irresponsible. It’s like saying that exposure to asbestos does not contribute to periodontal disease, therefore it’s safer than not flossing your teeth. Like the salt-glyphosate comparison, this is a statement that draws attention to an irrelevant health concern as a way of masking a relevant health concern. These kinds of comparisons come straight out of Shady Chemical Industry Tactics 101.

When looking at the harms posed by these two substances at concentrations that are much lower and more likely to be ingested by the average person, the picture changes dramatically. By far the most worrisome health harm from eating too much salt (sodium) is high blood pressure and hypertension, which can lead to cardiovascular disease or stroke. Currently, the American Heart Association, Food and Drug Administration and Centers for Disease Control and Prevention recommend a daily limit of 2,300 milligrams of sodium per day with an ideal limit of 1,500 milligrams per day.

Although researchers continue to explore the full scope of human health harms that can come from chronic glyphosate exposure, the most well-established harm is an increase in certain types of cancers. There is currently only one agency in the world that has attempted to identify a safe dose of glyphosate based on a cancer endpoint. California’s Office of Environmental Health Hazard Assessment has made the preliminary finding of a “no significant risk level” for glyphosate of 1.1 milligrams per day. This means that limiting your exposure to glyphosate to 1.1 mg per day will give you less than a 1/100,000 chance of developing cancer.

So the recommended limit of sodium intake is 1,500 mg per day, while the amount of glyphosate that won’t give you a significant risk of developing cancer is about 1,500 times lower than that. Unfortunately, we can’t really compare these values directly because they’re measuring different outcomes and used different methodologies, but what is abundantly clear is that the level of glyphosate that is considered safe is MUCH lower than that of table salt. So without the distraction of industry trying to say “if it doesn’t kill you, it’s safe,” what is clear is that glyphosate is NOT safer than table salt when it comes to long-term, chronic effects that can lower your quality of life and shorten your lifespan.

Since we’re already on the topic of comparing glyphosate to salt, it’s also important to compare the transparency with which these ingredients are disclosed. With high levels of salt intake correlated with disease in certain individuals, the FDA required nearly 30 years ago that foods display how much sodium they contain on the package label. Consumers don’t get any information whatsoever when it comes to finding out what pesticides were used on, and therefore may be present in, their food.

So not only is glyphosate more harmful than table salt, it’s also more difficult to avoid because of lack of transparency. With 300 million pounds of glyphosate used in the United States every year on agricultural crops, the typical person’s daily exposure is not insignificant. Because the majority of genetically engineered crops are sprayed directly with glyphosate and other herbicides, the failure of mandatory labelling of genetically engineered foods directly on the package — which could have given people at least some sense of which foods have higher glyphosate residues — ensures that this lack of transparency will be the status quo moving forward.

Stay wild,

Dr. Donley