There’s a lot to consider when building a healthy diet. You can tick the fibre and protein boxes, keep ultra-processed foods in check and still miss something important: how you cook.
A new study puts the spotlight on high-heat cooking methods such as grilling and smoking. When food cooks over high temperatures, especially over open flames, it can form polycyclic aromatic hydrocarbons (PAHs), a group of pollutants linked to cancer risk.
Does that mean you need to skip the cookout? Not necessarily. It means it’s worth knowing what PAHs are, how they form and what simple changes can reduce exposure without turning dinner into a chemistry lesson.
What are PAHs?
PAHs are chemicals that form when organic material burns incompletely. They show up in everyday environments, not just food.
“PAHs are a group of harmful chemical compounds formed from the incomplete burning of organic matter like coal, oil and wood,” says gastrointestinal medical oncologist Dr Tracy Proverbs-Singh.
In food, the main issue is smoke and char. “They are commonly created in our diet during high-temperature cooking, especially when grilling or smoking meat, as fat drips onto flames and produces PAH-rich smoke that coats the food,” Dr Proverbs-Singh says.
She adds that other exposure sources include “vehicle exhaust, industrial emissions and tobacco smoke.”
PAHs carry their biggest concern through their relationship with cancer risk.
“Many are classified as carcinogenic because, when ingested or inhaled, they can be metabolised into substances that bind to and damage a cell’s DNA,” Dr Proverbs-Singh says. “This DNA damage, if unrepaired, can lead to mutations that initiate cancer.”
She notes the strongest links include lung, skin and bladder cancers. She also says PAHs “can weaken the immune system and disrupt hormones.”
What did the study find?
Researchers tested a range of foods for PAHs using a lab extraction approach called QuEChERS, which stands for Quick, Easy, Cheap, Effective, Rugged and Safe. They measured eight specific PAHs, then compared which foods carried the highest levels of the PAHs they selected.
In this study, soybean oil showed the highest PAH levels, followed by duck meat, then canola oil.
The bottom line
The study did not make dietary recommendations about soybean oil, canola oil or duck meat. It focused on measuring PAHs and demonstrating a practical way to detect them. At the moment, there is no set PAH standards for food, and there is no set limits for PAHs in drinking water.
“While identifying PAHs in soybean oil is important, the study’s core achievement is validating a method that is not only highly accurate and sensitive but also quick and cheap,” says Dr Proverbs-Singh. “This efficiency is critical, empowering regulatory agencies and food producers to conduct widespread, cost-effective surveillance for harmful contaminants. Ultimately, the study's main contribution isn’t just a single finding, but a robust tool to better protect the public from harmful chemicals in the food supply.”
If you want to reduce PAH exposure, focus on the biggest, most consistent sources first. Charred, grilled or smoked foods tend to drive more exposure than most everyday cooking methods. This study also suggests a small list of ingredients that may contribute more than expected, depending on sourcing and processing. At the same time, broader testing and monitoring aims to keep contaminants out of the food supply before they reach your plate.
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