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• Posted August 13, 2025

Coffee Is Mostly Safe, Study Finds, But Some Contaminants Remain

Your morning coffee is mostly free from harmful levels of toxins and contaminants, but a new investigation shows there’s room for improvement.

“While some contaminants were present, most were found at minimal levels and well below the European Union’s safety limits per 6-ounce serving. This means coffee is generally safe,” Molly Hamilton, executive director of the nonprofit Clean Label Project, which led the testing, told CNN.

Research has linked drinking about 3 cups of black coffee a day to a lower risk of heart disease, type 2 diabetes, liver disease, stroke, dementia and more.

The Clean Label Project analyzed coffee from 45 popular brands grown in Brazil, Colombia, Costa Rica, Ethiopia, Guatemala, Kenya, Peru and Hawaii. More than 7,000 tests were run for pesticides, heavy metals, plasticizers and mold toxins.

The results:

• Glyphosate: Traces of this widely used weed killer were found, along with “significant” amounts of aminomethylphosphonic acid (AMPA), its byproduct. AMPA can persist in the environment and has been linked to DNA damage and liver inflammation.

• Phthalates: These plastic chemicals, linked to reproductive issues, childhood obesity, cancer and asthma, were detected in some coffees. Levels were highest in canned coffee, followed by pods, then bags.

• Heavy metals: Amounts varied by region, with African coffees having the lowest levels and Hawaiian coffees the highest, likely due to volcanic soil. Examples of heavy metals include lead, mercury and arsenic.

• Acrylamide: All samples contained small amounts of this chemical, which forms during roasting. It has been linked to cancer in animal studies but is not considered harmful to humans at low levels. Medium roasts had the most acrylamide, followed by light roasts, then dark roasts.

Organic coffees generally had lower contaminant levels, but all 12 organic samples still contained AMPA. Hamilton said this could owe to runoff from nearby conventional farms.

"Our next study is going to be analyzing the packaging assembly line,” he said in a report from CNN.

David Andrews is acting chief science officer for the Environmental Working Group.

“The higher phthalate levels found in coffee pods and canned coffee suggest that packaging could be a meaningful source of exposure to these chemicals of concern,” he told CNN.

The National Coffee Association (NCA), however, pushed back, telling CNN that it's “highly irresponsible to mislead Americans about the safety of their favorite beverage.”

“Decades of independent scientific evidence show that coffee drinkers live longer, healthier lives,” NCA President and CEO William “Bill” Murray said.

Hamilton said coffee drinkers can limit contaminants by:

• Choosing darker or very light roasts

• Opting for coffee in bags or pods 

• Considering where the coffee is grown

“Caffeinated coffee is still one of the cleanest product categories we’ve ever tested," Hamilton said.

“Our report isn’t meant to raise alarm or keep consumers from drinking coffee, but rather to empower people on how to choose the cleanest, safest cup of coffee,” he added.

More information

NutritionFacts.org has more on light versus dark roast coffee.

SOURCE: CNN, Aug. 11, 2025