McDonald’s french fries are not made from potatoes treated with the pesticide Monitor

Several social media posts claim that a pesticide called Monitor is used to grow potatoes for McDonald’s french fries. But this is not true in the UK, EU and US at least, where the pesticide has not been approved for use for years.

Many of the posts quote claims that were originally made by journalist and author Michael Pollan in a speech at a Royal Society of Arts event in 2013. Some posts link to footage of him speaking and have thousands of shares. 

But these posts fail to explain that Monitor has not been approved for use in the US since 2009 and the EU since 2008. McDonald’s USA told Full Fact that the chemical had not been used on its potatoes for “several years”, and Mr Pollan also told us it was no longer used in the US, adding that his 2013 account was based on reporting he had carried out in the late 1990s.

Full Fact has previously written about false and misleading online claims relating to food and drink, such as that maggots are allowed in orange juice in the US and that water is poisoning residents in Greater Manchester. Misinformation like this can create unnecessary alarm, uncertainty and distrust about what is safe to consume.

What did Mr Pollan say in 2013?

In his speech, which is quoted in many of the posts, Mr Pollan said McDonald’s insists that all its fries are made from Russet Burbank potatoes. He went on to claim that only a pesticide called Monitor can protect these potatoes from “net necrosis”, which creates the brown blemishing sometimes seen on the vegetables and is a symptom of a viral infection spread by aphids (insects that suck the sap of plants). 

Monitor is a trade name for a chemical called methamidophos, which has historically been used as an insecticide on a variety of crops. In the EU, this included tomatoes, soybeans, tobacco, sugar and cotton among others, while in the US this included cotton, potatoes and tomatoes.

Methamidophos is classed as ‘highly hazardous’ by the World Health Organisation and stopped being registered for use as a pesticide in the US in 2009. McDonald’s USA confirmed to Full Fact that Monitor has not been used on its potatoes for “several years”. 

Fact checking organisation Politifact has also pointed to the absence of methamidophos in a video commissioned by McDonald’s as part of a 2014 promotional campaign to explain the 19 ingredients used to make its french fries. 

Methamidophos has also not been approved for use in the EU since 2008, and this has continued to be the casein the UK since Brexit. McDonald’s UK’s website says all pesticides used to grow its potatoes are approved under EU legislation and that its suppliers do not use pesticides containing methamidophos. 

While we know Monitor is not used in the UK, EU and US, we have not been able to verify whether it could be in use anywhere else in the world. We have asked McDonald’s about this and will update this fact check when we hear back.

‘No-entry zone’

Several posts also claim that farmers have to observe a “no-entry zone” after spraying Monitor. Mr Pollan claimed in the video from 2013 that “Monitor is so toxic that the farmers who grow these potatoes in Idaho won’t venture outside into their fields for five days after they spray”. 

This is missing context—the practice is a standard safety protocol carried out after any pesticides are used. Politifact reports that commercial farms in the US are required to observe a “restricted-entry interval” (REI) for a period immediately after a pesticide is applied. 

The length of time varies depending on the crop, specific pesticide and the amount of human contact required for the agricultural activity, varying between 12 hours or multiple days. When it was previously approved for use, the REI for methamidophos in the US was four days for potatoes. 

Potatoes don’t need to ‘off-gas’

Some of the posts we’ve seen share another claim mentioned in Mr Pollan’s speech—that the harvested potatoes are “not edible” for six weeks and need to be kept in “atmosphere-controlled sheds” to “off-gas all the chemicals”.

According to the Office for Science and Technology at McGill University in Montreal, Canada, the notion that potatoes have to be stored to “off gas toxins” is “pure nonsense”. It says potatoes are routinely stored that way to make sure they are available all year round. 

Crops grown or imported into the UK are monitored to ensure any traces of pesticides are within safe levels. 

What does Mr Pollan say?

We contacted Mr Pollan to alert him to the claims now circulating. 

He said: “It's true that Monitor is no longer in use in the US. My account is based on reporting I did in the late nineties. I'm glad you will be updating it.”

Image courtesy of Dinkun Chen