McDonald's has a controversial new item 

The fast-food chain has added something new nationwide that's sure to make some customers angry.

Certain foods simply no longer get served in restaurants for a variety of reasons.

You can't buy foie gras in the United States anymore because many Americans consider the process used to make the fattened duck liver delicacy cruel. And while fast-food chains probably never considered selling foie gras, the same controversy caused (at least partially) Restaurant Brands International's (QSR) - Get Free Report Burger King to drop its veal parmesan sandwiches in the 80s. 

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Burger King has brought back its chicken parmesan "long" sandwich, in fact it's on menus now, but the veal disappeared in the early 80s and has never come back. It's not only animal rights activists who have forced restaurants to make changes. 

Some foods are only served selectively because as a society we have become more sensitive to people with life-threatening allergies. Being allergic to a food can mean different things. Some people experience gastrointestinal problems if they ingest gluten or dairy while others have allergies that can cause airways to close up, leading to a possible death.

That's why so many schools across the country ban peanut butter and other peanut-containing products. Peanuts are a common allergen that people can have serious, even terminal, reactions to and that has largely kept peanuts off the menus at fast-food chains.

You can trust workers in a high-end restaurant to learn about risks and cross-contamination. Asking the same of lower-paid fast-food workers may increase the risk of a problem. That's at least partially why McDonald's (MCD) - Get Free Report has made the crushed peanut topping for its sundaes optional for franchisees and many have dropped it.

Now, despite the fact that some people with peanut allergies can have a reaction from a small amount of cross-contamination -- the chain has added a new Peanut Butter  Crunch McFlurry nationwide. 

McDonald's McFlurry machines are famously unreliable. 

Image source: McDonald's

McDonald's menu adds a new McFlurry    

There are no laws forcing McDonald's to not sell peanut-based products or, in most cases, even rules requiring them to disclose the presence of peanuts in their stores. Still, the chain has largely avoided having dangerous allergens on its menus, especially ones where if someone makes a McFlurry for someone else and then gets peanut residue on their french fries, certain customers may have a serious reaction.

Still, the chain has rolled out the Peanut Butter Crunch McFlurry nationwide. 

"The rumors are true: the Peanut Butter Crunch McFlurry is officially making its way to participating McDonald’s locations nationwide starting August 9. Made with our signature creamy vanilla soft serve and blended with crispy cereal mix and chocolatey peanut butter cookie pieces, this sweet treat will be available for a limited time, while supplies last," the chain shared.

McDonald's did not answer a request for comment.

McFlurry has faced a lot of McProblems

Since the McFlurry hit McDonald's menu in 1997, the machines that make it have gained a well-earned reputation for breaking down. That led to the website, McBroken.com, which exists to answer the question: "Is the McDonald's ice cream machine broken?"

The McFlurry maker is actually not the machine that dispenses soft serve for the chain, so it's possible to get an ice cream cone or sundae at times you can't get a McFlurry. On August 12, the website reported that over 12% of the McFlurry machines were down. 

Those numbers were worse on that same day in New York (30.61%), San Francisco (26.67%), and the company's home market of Chicago where just under 20% of the machines were not functioning.