Which caffeinated coffees have toxins?

December 31, 2025 •

5 min read

According to recent testing by the Clean Label Project, while caffeinated coffee is one of the cleanest product categories tested, some still contain trace contaminants. This raises the critical question: which caffeinated coffees have toxins and what should consumers be aware of to make informed choices?

Quick Summary

Some coffees may contain trace amounts of mycotoxins, acrylamide, pesticides, and other contaminants due to various factors in the production process. While these levels are typically far below safety limits, consumers can reduce their exposure by selecting brands with rigorous quality control, considering roast level and bean processing, and ensuring proper home storage.

Key Points

Mycotoxins are a Potential Threat: Molds producing toxins like Ochratoxin A and Aflatoxin can grow on coffee beans, especially with improper drying and storage.
Acrylamide Varies with Roast: The probable carcinogen acrylamide forms during roasting, with the highest levels typically in medium roasts; opt for light or dark roasts to minimize exposure.
Pesticides Can Contaminate Organics: Residues of pesticides like glyphosate and its byproduct AMPA can appear even in organic coffee, possibly from environmental runoff.
Packaging Contributes Toxins: Plasticizers (phthalates) and heavy metals from packaging can leach into coffee, with canned and pod coffee showing higher levels.
Proper Processing and Storage are Key: Wet-processed beans, high-quality sourcing, and proper home storage in cool, dry, opaque, and airtight containers are crucial for safety.
High-Quality Beans Reduce Risk: Specialty grade and certified organic beans are generally subjected to more rigorous quality control and testing, reducing the likelihood of contaminants.
The Risk is Contextual: While toxins can be present, levels in most commercially available coffee are low and well below regulatory safety limits, meaning the health risks are considered minimal for the average consumer.

Understanding Contaminants in Your Cup

Despite the many proven health benefits of coffee, including reducing risks for diseases like type 2 diabetes and liver disease, some naturally occurring and processing-related compounds can raise consumer concern. It is important to understand what these substances are and how they may end up in your morning cup, acknowledging that reputable manufacturers actively work to minimize these risks.

Mycotoxins: The Fungal Threat

Mycotoxins are toxic compounds produced by certain molds and fungi that can grow on crops like coffee beans, particularly under warm, humid conditions with poor storage or drying. The two primary mycotoxins of concern in coffee are Ochratoxin A (OTA) and Aflatoxin B1.

Ochratoxin A (OTA): Produced by Aspergillus and Penicillium species, OTA is nephrotoxic (harmful to kidneys) and a possible carcinogen. It is most likely to form during the drying and storage phases of green coffee beans. While roasting significantly reduces OTA levels, it does not completely eliminate them. Regulatory limits exist in many countries to protect consumers.
Aflatoxin B1: This is considered one of the most potent natural carcinogens and is primarily associated with peanuts and grains but can also contaminate improperly stored coffee. High-quality processing and storage are crucial in preventing its formation.

Acrylamide: A Product of Roasting

Acrylamide is a chemical compound that forms naturally in starchy foods, including coffee beans, when they are roasted at high temperatures (above 250°F / 120°C). It is considered a probable human carcinogen at very high doses, but the risk from dietary consumption is generally considered low. The levels of acrylamide in coffee vary depending on the roast level:

Highest levels: Often found in medium roasts, where beans are roasted at high temperatures long enough to form the compound but not long enough to break it down.
Lower levels: Found in both very light roasts (minimal heating) and very dark roasts (longer heating breaks down the acrylamide).

Pesticides and Herbicides

Conventionally grown coffee, which makes up a large percentage of the market, is often treated with pesticides and herbicides to protect crops. While the roasting process can eliminate some of these residues, it does not remove all. The presence of glyphosate and its byproduct, aminomethylphosphonic acid (AMPA), has been detected in both conventional and, surprisingly, some organic coffees. This is believed to be due to environmental factors like runoff from nearby farms. Choosing certified organic coffee significantly reduces, but does not entirely eliminate, the risk of pesticide exposure.

Other Contaminants: Heavy Metals and Plastics

Packaging can also introduce contaminants. A 2025 study highlighted that phthalates, plasticizing chemicals linked to various health issues, were found in some coffees, with canned coffee showing the highest levels, followed by pods and bags. Additionally, heavy metals like lead and cadmium can be absorbed from the soil where coffee is grown. Regional variations exist, with Hawaiian coffee sometimes showing higher levels due to volcanic soil.

Factors Influencing Contaminants in Coffee

Contamination is not a foregone conclusion. The coffee industry employs various practices to reduce or prevent the formation of toxins. Your choices as a consumer also play a key role in minimizing exposure.

Comparison Table: Factors Influencing Coffee Contaminants


Factor	Impact on Mycotoxins	Impact on Acrylamide	Impact on Pesticides
Roast Level	Darker roasts reduce levels more significantly than lighter roasts.	Highest in medium roasts; lowest in very light and very dark roasts.	Roasting can reduce, but may not eliminate, residues.
Processing Method	Wet-processing removes more mold and mycotoxins than dry-processing.	Negligible impact, as acrylamide forms during the roasting stage, not processing.	Negligible impact, relates more to farm management.
Storage Conditions	Cool, dark, dry storage is essential to prevent mold growth.	Minimal impact, though proper storage preserves overall quality and reduces moisture.	Minimal impact, relates more to farm and processing.
Bean Quality	Specialty grade beans are typically monitored for quality and contamination more rigorously.	Higher quality beans, particularly Arabica, can have lower levels compared to Robusta.	Organically grown beans have minimal to no pesticide residue.
Bean Origin	Origin can influence mycotoxin risk due to climate and processing standards.	Similar impact across most origins, determined by roasting practices.	Regional soil and farming practices affect heavy metal content.

How to Minimize Your Exposure to Coffee Toxins

While alarmist claims about coffee and toxins are often exaggerated, and regulatory standards ensure most products are safe, a proactive approach can further minimize your exposure. The benefits of consuming coffee are well-documented, so the goal is not avoidance but smart selection. Here’s how you can make more informed choices:

Choose High-Altitude, Organic, and Specialty Grade Beans: High-altitude beans are less susceptible to pests, reducing the need for pesticides. Organic certification avoids synthetic pesticides, while specialty grade beans have passed rigorous quality tests. Sourcing beans from reputable suppliers with transparent practices offers the best assurance.
Select Washed (Wet-Processed) Beans: The wet-processing method involves washing the coffee cherries to remove the pulp, which significantly reduces the risk of mycotoxin-producing mold growth. This is often the process used for high-quality Arabica beans.
Opt for Light or Dark Roasts: To reduce acrylamide exposure, choose either a very light or very dark roast. Dark roasts are roasted longer, which breaks down the compound, while light roasts are minimally processed and avoid its formation.
Store Properly at Home: Protect your coffee from heat, light, air, and moisture, which can cause mold growth and oxidation. Store beans in an opaque, airtight container in a cool, dark pantry. Avoid storing coffee in the refrigerator.
Purchase Whole Beans and Grind Fresh: Grinding beans increases their surface area, accelerating oxidation and flavor loss. Grinding immediately before brewing preserves freshness and flavor.
Buy Coffee Packaged in Bags: Packaging matters. Canned and pod coffees showed higher levels of phthalates in recent testing, so choosing bagged coffee can reduce this risk.

Conclusion: Making Informed Choices for a Safer Brew

For most people, the trace amounts of potential toxins in commercially available coffee pose minimal risk, and the beverage's health benefits are widely supported by scientific evidence. However, by understanding the sources of contamination and making strategic choices regarding the coffee you purchase and how you store it, you can further minimize your exposure and ensure a cleaner, healthier cup.

While complete avoidance of all environmental toxins is impossible, being a discerning consumer empowers you to make better decisions. Choosing high-quality, specialty-grade, organic coffee from suppliers with robust testing practices is the most effective strategy. Ultimately, awareness and simple best practices can help you continue enjoying your favorite beverage with confidence.

For more detailed findings on common consumer product contaminants, consult reports from non-profit organizations like the Clean Label Project.

Frequently Asked Questions

No, most commercially available caffeinated coffees are not guaranteed to have toxins. Testing often finds only trace amounts of contaminants, and reputable brands using careful sourcing and processing keep levels well below established safety limits.

Roasting coffee significantly reduces mycotoxin levels, but it does not eliminate them entirely. The effectiveness depends on the original contamination level and the roast darkness.

Very dark or very light roasts are the best choices for minimizing acrylamide. Medium roasts tend to have the highest levels because they are roasted at higher temperatures for a duration that promotes formation but not complete breakdown.

Organic certification significantly reduces the risk of pesticide exposure, but it does not guarantee a complete absence. Contaminants like glyphosate's byproduct, AMPA, can be found in some organic coffees due to environmental contamination from sources like water runoff.

Store coffee beans in an opaque, airtight container in a cool, dark, and dry place. Avoid storing them in the refrigerator, as fluctuating temperatures and humidity can promote mold growth and moisture absorption.

Yes, the processing method can affect mycotoxin levels. The 'wet' or 'washed' method, where coffee cherries are immediately washed, can remove more mold and mycotoxins than the 'dry' or 'natural' method.

Recent testing suggests that canned and pod coffees can have higher levels of phthalates, plasticizing chemicals from packaging, compared to coffee packaged in bags. For this reason, many health-conscious consumers prefer bagged coffee.