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I read on the internet that there are dangerous levels of a toxic weed killer in many common vaccines.  Is this true?  Should I be worried? – Rebecca T., Wilton, CT.

Great question to start off our Ask a Scientist series, Rebecca.  Here are the facts:

This claim was posted online by a group called Mom’s Across America (or MAA, which is the guttural noise of frustration that I make after reading their website). I’m not linking to their site because it contains biased anti-GMO, anti-chemical info while also conveniently selling their own line of homeopathic health supplements. They sell a product for “mineral health”, which is not a thing, and it contains “72 essential trance minerals.” Mind you they don’t say what these essential minerals are, nor do they address the fact that there are less then 20 scientifically accepted essential minerals. I think you get the point.

Allegedly, MAA went out an bought several common vaccines and sent them to a private lab for analysis. The lab claims to have found glyphosate, which is the active ingredient in Round Up, the most commonly used weed killer in the United States.

There are a lot of problems with this work and reasons to be skeptical. First of all, this is an obviously biased group commissioning a small study to a private lab, and sharing the results over the internet rather than a peer-reviewed journal. Not exactly a reliable source – literally no respectable science is ever published this way.

Secondly, the methods used were not appropriate, and generally not sensitive enough to measure these quantities accurately. Here’s an excellent article on the subject which does a great job of discussing the technical issues with the methods.

While we’re on the subject of the methods, they used an antibody based assay. Antibodies are very specific, binding only a single molecule rather then allowing the user to screen for whatever might be present in the sample. which means they were looking for glyphosate specifically. So why were they looking for this compound?  It’s certainly not an ingredient in vaccines, and the FDA is VERY strict about quality control of impurities in medicines. MAA’s rationale seems to be that “glyphosate herbicide sprayed crops are ingredients of vaccines or are fed to livestock [and]…glyphosate could easily be present in vaccines due to the fact that certain vaccine viruses (including measles in MMR and flu virus) are grown on gelatin derived from the ligaments of pigs fed heavy doses of glyphosate in their GMO feed.”

That makes very little biological sense.  First, “herbicide sprayed crops” are not ingredients in vaccines.  Second, vaccines aren’t  “grown on gelatin”, gelatin is just one of many ingredients in the culture. Yes it can come from pigs, but it also comes from cows and fish, and many different parts of the animal other than ligaments (mostly bone). Also, one of the reasons we use glyphosate so much today is that it doesn’t get into food very well. It kills the weeds you spray it on, but isn’t actually taken up form the soil effectively afterwards, which is why it doesn’t kill the flowers or vegetables right next to the weed you sprayed. It’s also highly water soluble, which means it’s cleared from the body quickly, unlike the old school pesticides (like DDT) that caused so much environmental damage. Since it doesn’t accumulate in the tissues of animals, it’s extremely unlikely that ligaments from pigs would have high concentrations of the pesticide, even if they somehow managed to consume massive amounts of food crop that had been sprayed with glyphosate.

But even if we assume the claims made by MAA are true, would these levels actually pose a risk to your child?  There’s an old saying in toxicology: “the dose makes the poison,” which means that anything can be toxic if you are take enough of it, and nearly anything can be safe if you take a low enough dose. For example, you can die of water poisoning just as easily as you can die from eating rat poison, the only difference is how much you consume (the dose level). As far as pesticides go, glyphosate is not particularly toxic to humans, because it was specifically designed to target enzymes that plants have, but mammals lack.

So are the levels reported here high enough to cause harm? No. These levels are LOW. The highest levels that MAA claim to have measured (in the MMR vaccine) was 2.671 ppb. (Ppb stands for parts per billion, which basically means that for every billion molecules in this vaccines, there would be less than three molecules of glyphosate.) Based on these levels, a typical recipient would receive a 1.5 ng dose of glyphosate from the vaccine. (ng stands for nanogram, which is 1 billionth of a gram – an extremely tiny amount). We can compare this to what are considered safe levels of glyphosate – allowable daily intake (ADI) levels which are set by world health authorities based on the known toxicity profile of a compound. The ADI for glyphosate in Europe is 0.3 mg/kg/day. This is approximately 2 million times higher than the levels MAA reports for the MMR vaccine. In the United States, the ADI levels are actually 5 times higher than the European standard (1.75 mg/kg/day), which means that the US EPA considers it safe for you & I to be exposed to approximately 10 million times the levels reported by Mom’s Across America ON A DAILY BASIS.

To recap, we are talking about a privately-commissioned report that hasn’t been peer-reviewed, written by a biased group clearly looking for this weed killer in a place they couldn’t reasonably expect to find it. They used faulty methods, and even if we were to take their results at face value, the pesticide levels they reported are still way, way, way lower than any levels that would be associated with adverse effects of this herbicide. So, Rebecca, to answer your first question (is it true?), the answer is probably not.  The answer to your second question (should I worry?) is nope.