Should You Be Worried About Fertility-Damaging Chemicals In Your Oats?
Why the recent news about chlormequat isn't nearly as scary as you might've heard
Humans have a love/hate relationship with modern farming techniques. Most of us wouldn’t be alive today if we hadn’t invented things like pesticides and herbicides, but also there is quite a lot of history showing that overuse of these chemicals is disastrous for our health.
This tentative relationship is very clear this week, with numerous headlines proclaiming that nasty chemicals are making us all infertile. Specifically, the media stories are about a new study that has apparently shown that 80% of Americans have the little-known chemical chlormequat in their urine, and that this chemical is also present in many common brands containing oats that you’d find on grocery shelves.
But as with many of these stories, the hype far outweighs the findings. Yes, there are some chemical residues in common foodstuffs, but these are almost certainly safe and well under regulatory limits.
The Study
The new paper that has the world terrified of oats is a study funded by the Environmental Working Group looking at chlormequat residues in urine and oat products in the United States. If you are unfamiliar with the EWG, they are an activist nonprofit organization that lobbies for tighter limits on various chemicals such as pesticides and herbicides. They are also part-funded by payments from the organics industry, and promote organic farming in a variety of ways.
In this paper, the authors did two things. Firstly, they purchased 96 urine samples from commercial labs and tested them for chlormequat. These samples were from three labs - 21 from South Carolina taken in 2017, 25 from Missouri taken in 2017-22, and finally 50 from Florida taken in 2023. Aside from gender, the authors have provided no information about the people these samples were taken from.
The study then looks at 42 samples taken from 25 different oat-based products which were purchased by the authors in mid-2023. All of these samples were tested for residues of chlormequat.
The authors found very small amounts of chlormequat in 77/96 human urine samples, and 23/25 oat products tested. Thus, they concluded that there needs to be more regulatory action to review the rate of chlormequat exposure in the US.
However, I’m not particularly concerned about their findings. As the saying goes, the dose makes the poison, and these doses are REALLY small.
Some context is useful here. Chlormequat is a chemical used to modify plant growth, and it’s only used in certain crops. Unlike popular herbicides/pesticides, this means that it’s not ubiquitous in the supply chain, and we aren’t exposed to all that much of the chemical.
The urine samples show exactly this. The authors report chlormequat residues in ranges of micrograms per gram of creatinine in urine. A normal adult will pee out about 0.5-2g of creatinine a day, so very roughly 0.1-0.2g per urination (depending on a variety of factors). In this study, the average chlormequat concentration in urine was around 0.000000001g/g of creatinine, while the highest intake was 0.0000000528g/g. Given that chlormequat is rapidly excreted from the body, this equates to an absolutely minuscule intake of the chemical, somewhere in the region of 50 billionths of a gram (or nanograms), daily.
The same is true for oat products, which were mostly a variety of cereals like Cheerios and other oat-based foods. The authors described the results of the oat product testing in parts per billion, with the highest reported figure being from Quaker’s Old-Fashioned Oats at 291ppb. That means that to get a single milligram of chlormequat from these products, you’d have to eat about 3 kilograms/6.6 pounds of the stuff.
Now, that’s not necessarily reassuring. Some things can be dangerous even in concentrations of parts per billion. For chlormequat, based on a series of animal studies, the upper limit for chronic human exposure set by the US EPA is 0.05mg/kg body weight per day. This is based on the No Observed Adverse Event Level (NOAEL) derived from the animal studies of about 5mg/kg body weight daily, which is then divided using a series of calculations including additional margins of error for children and pregnant women. Essentially, the regulatory agency looks at the highest dose that causes no issues for animals in any study, and then divides it by 100 to ensure that any harm to humans will be incredibly unlikely.
For your average human child, that means that the maximum threshold for chlormequat exposure allowed by the US EPA is about 1mg per day, which as I’ve noted is about 3kg/6.6lb of oat products. So unless your kids are eating literal tons of these foods, the risk is negligible. Even the adult urine concentrations found in the paper are so low that they are almost certainly safe, aside perhaps from the one person in the study who tested at a rate of 50x the average.
Safe Eating
The problem with stories like this is that they sound really scary, but it takes a huge amount of time, effort, and expertise to really understand the risks. Most of the reporting has simply taken the EWG at their word, but realistically the findings are very limited in what we can say about them.
For example, the human urine samples were taken from completely arbitrary people who we know nothing about in just three locations in the US. Are these agricultural workers who might be exposed to far more chlormequat than the average person? We have no idea. Moreover, the fact that these samples are from different people in different states in different years means that you can’t make any conclusions at all about population exposures.
The claim that “80% of Americans” test positive for chlormequat residues is entirely false. Rather, in a really bad sample of people from three states, 80% of urine samples had some chlormequat residue. In addition, the argument that there is a significant increase in chlormequat levels over the last 6 years is simply not true - all this study can tell us is that some random people from Florida in 2023 had more of the stuff in their urine than some other random people from Missouri in 2022.
Ultimately, this study is incredibly limited and tells us little about chlormequat exposure or dangers in the US. The amounts found were mostly orders of magnitude lower than the intake levels set by the EPA, and it’s very unlikely that people are currently being poisoned by their Cheerios. Given that the US has recently increased the allowed chlormequat intake in products sold in the country, it’s not a bad idea to increase monitoring of the chemical, but this particular study shows very little that’s a cause for concern.