Restaurant food arrived in a black plastic box? Nutrition doctor issues health warning. 'Don’t reheat'

A medical nutrition expert has raised concern about the black plastic containers widely used by restaurants for food deliveries. Dr Nandita Iyer, a medical doctor with a fellowship in applied nutrition and over 18 years of experience in nutrition, medical advertising and writing, has spoken about what she believes is an overlooked risk. She is also the author of The Great Indian Thali.

In a video shared on X, Dr Iyer directly addressed people who regularly order food online. She said, “Did you get your last food delivery in this kind of container? If yes, stop scrolling. I'm the last person to be fear-mongering. But this is one thing you should pay attention to. Almost all restaurants use this to deliver food. Some people I know even collect these containers for future use in their kitchen or maybe add to their children's inheritance.”

Her message was simple. She is not asking people to panic. But she wants them to think twice before reusing or heating food in these containers.

Why Black Plastic Is a Concern

According to Dr Iyer, most black plastic containers are made from recycled plastic waste. This waste may include materials from electronic products and other non-food items. She explained, “Black plastic is often made by recycling potentially contaminated plastic waste. Some of it contains residues of electronics like TVs, remotes, old PVCs, flame retardants, which are definitely not food safe. And the black color dye helps mask the mishmash of plastics combined to make these boxes.”

Her concern is that the black pigment hides the mixed and sometimes unknown composition of the plastic. Because it comes from different sources, it becomes harder to trace what exactly went into making the container.

Heating Makes It Riskier

Dr Iyer pointed out that the problem may increase when these containers are heated. She said, “There's also evidence that black plastic, especially when heated in the microwave or in the presence of acid or fats, which is in our curries, using black plastic ladles or spoons in hot food leeches higher levels of harmful compounds, including these brominated flame retardants and heavy metals.”

In simple terms, when hot curries, oily gravies or acidic foods sit in these boxes, or when people microwave food in them, the chances of chemicals leaching into the meal may rise. She referred to harmful compounds and even traces of heavy metals as possible risks.

Not All Plastic, But This One Swap Matters

At the same time, Dr Iyer clarified that not every black plastic item is automatically dangerous. However, she believes the uncertainty around their source makes them unsafe enough to avoid. She said, “While not every black plastic item is dangerous, many are made from these poorly traceable recycled materials, which increases the risk. So, it's definitely not worth taking the chance. I'm not asking you to throw away every plastic container from your kitchen or the ones that stock dry groceries. But if you're going to make this one plastic swap today, make it this. Replace black plastic containers with safer alternatives. Talk to the restaurants you regularly order from not to use these black plastics for delivery.”

She added that even white plastic containers are generally considered safer than black ones. However, she also warned that many paper takeaway boxes are lined with a thin plastic layer. When hot food is placed in them, the risk remains similar.

Dr Iyer said, “Even the white plastic boxes are better. Paper boxes are often lined with a thin layer of plastic on which hot food is put. And it is the same as using hot food in any other plastic container. Only this is even tougher to recycle. So when you get your food in these containers, transfer them to food safe glass or steel containers immediately. And definitely do not microwave them in these black plastic containers.”

Her advice is practical. Transfer the food to glass or stainless steel once it arrives. Avoid reheating in black plastic boxes. And if possible, ask restaurants to consider safer packaging. It may feel like a small step, but according to her, it is one change that can reduce unnecessary exposure to harmful substances.