A new study testing 57 of America's best-selling coffees uncovered a troubling paradox: every single organic coffee tested contained AMPA, a toxic breakdown product of the herbicide glyphosate, despite the fact that glyphosate is banned for use on organic crops. The Clean Label Project, which conducted over 7,000 individual tests for contaminants including heavy metals, mycotoxins, pesticides, and chemical residues, found that while coffee remains one of the cleanest food categories tested, certain packaging types and roast levels expose you to significantly higher levels of harmful compounds than others.

The coffee market is massive, generating $269 billion globally in 2024 and projected to reach $369 billion by 2030. Yet the United States has no federal contaminant regulations for coffee, and the beverage is exempt from California's Prop 65 safety standards. This regulatory gap means consumers have little transparency about what's actually in their morning cup.

How Did AMPA End Up in Organic Coffee?

The presence of AMPA in 100% of organic coffees tested is particularly puzzling because glyphosate itself is prohibited in organic farming. AMPA is a persistent breakdown product that forms when glyphosate degrades in the environment. Researchers believe the contamination likely occurs through environmental exposure in coffee-growing regions where glyphosate was historically used, or through cross-contamination during processing and storage.

AMPA has been linked to health concerns similar to those associated with glyphosate itself. Studies have shown that childhood exposure to AMPA may increase the risk of liver stress and damage in early adulthood, and one small cohort study associated AMPA exposure with increased breast cancer risk. The chemical is considered persistent in the environment, meaning it doesn't break down easily and can accumulate over time.

What Other Contaminants Did Researchers Find?

Beyond AMPA, the Clean Label Project identified multiple concerning substances across the coffee samples tested:

• Acrylamide: Found in 100% of coffee samples, this chemical forms during high-temperature roasting and has been linked to nervous system effects and potential reproductive issues. Dark and light roasts had the least acrylamide, while canned coffee contained significantly more than bagged or pod varieties.
• Heavy metals: Arsenic, cadmium, lead, and mercury were detected in every coffee product tested, though all fell within European Union limits per serving. African coffees showed the lowest heavy metal levels, while Hawaiian coffee had the highest, likely due to volcanic soil composition.
• Glyphosate: Only two samples contained detectable glyphosate, likely because the roasting process breaks down this chemical. However, 72% of all samples contained AMPA, the persistent breakdown product.
• Phthalates: These packaging-related chemicals, which can interfere with hormones, were assessed across different container types, with canned coffee showing higher levels than bagged or pod options.

Which Packaging and Roast Choices Matter Most?

The study revealed that how your coffee is packaged and roasted significantly affects your exposure to contaminants. Choosing bags or pods over cans reduced acrylamide exposure substantially. Similarly, selecting dark or light roast coffee instead of medium roast resulted in lower acrylamide levels. These practical choices can meaningfully reduce your intake of harmful compounds without requiring you to eliminate coffee from your diet.

The geographic origin of coffee also matters. African coffees consistently showed lower heavy metal contamination compared to coffees from other regions, making origin a useful consideration when selecting products.

What About Mycotoxins in Coffee?

Beyond the Clean Label Project's findings, mycotoxins represent another significant concern in coffee safety. Mycotoxins are toxic compounds produced by molds that grow on coffee beans during cultivation, harvesting, and storage. Unlike the mold itself, these toxins survive the roasting process and transfer into your brewed cup.

The two primary mycotoxins found in coffee are ochratoxin A (OTA) and aflatoxin B1. Ochratoxin A is the more commonly detected mycotoxin in retail coffee and can damage kidney function with repeated exposure at high doses. Aflatoxin B1 is classified as a confirmed human carcinogen, though it is far less common in roasted coffee than in raw agricultural commodities because roasting degrades it substantially.

The European Union established a maximum limit of 3 micrograms per kilogram for ochratoxin A in roasted coffee as of January 2023, while the UK previously allowed 10 micrograms per kilogram. Typical retail coffee contains between 0.5 and 2.5 micrograms per kilogram, generally falling within these limits. However, the European Food Safety Authority (EFSA) noted in a 2020 reassessment that there is no established safe lower threshold for OTA exposure, and the research has not conclusively determined a fully safe intake level.

How Do Mycotoxins Get Into Coffee?

Mycotoxin contamination begins at the farm and progresses through every stage where moisture meets organic material without adequate temperature control. Growing conditions in tropical climates, harvesting methods that leave beans exposed to soil moisture, and processing techniques all influence final contamination levels. Dry-processed coffees, where the whole cherry dries with fruit pulp intact, show higher aflatoxin levels than wet-processed coffees where the pulp is removed immediately.

The post-processing drying stage is where most ochratoxin A contamination occurs. Under-dried beans stored in humid conditions provide ideal conditions for mold growth. Roasting reduces ochratoxin A by approximately 69% to 96% of its original concentration, but the remaining 4% to 31% survives into your cup. Between 80% to 100% of remaining mycotoxins transfer from ground coffee into brewed liquid, meaning your brewing method provides little protection against what was already in the bean.

Steps to Reduce Your Exposure to Coffee Contaminants

• Choose bagged or pod coffee over canned: Canned coffee showed significantly higher levels of acrylamide and phthalates, likely due to extended contact with metal packaging and processing methods.
• Select dark or light roast instead of medium: Medium roast coffees contained higher acrylamide levels than darker or lighter roasts, making roast level a simple way to reduce exposure.
• Prioritize African-origin coffees when possible: Coffees sourced from African regions consistently showed the lowest heavy metal contamination across the study's samples.
• Look for brands that test for mycotoxins: While regulatory limits exist, not all producers actively test for mycotoxin contamination. Seeking out brands that disclose testing results provides additional assurance.
• Limit daily consumption if using unvetted sources: While regulated commercial coffee poses minimal acute risk for most adults, heavy daily consumption from poorly regulated sources adds to overall dietary exposure to contaminants.

The broader takeaway from both studies is that coffee remains relatively safe compared to many other food categories, but informed choices about packaging, roast level, and origin can further reduce your exposure to contaminants. The regulatory landscape continues to evolve, with the European Union implementing stricter mycotoxin limits and increased scrutiny on pesticide residues. For American consumers, the absence of federal coffee contaminant standards means individual diligence and brand transparency become even more important.