Mycotoxins: Fungal Toxins from Grains
Mycotoxins are toxic compounds produced naturally by certain molds (fungi) that can grow on crops like barley, maize, and other cereals used in brewing. The presence of mycotoxins in beer is a direct result of using contaminated raw materials. The brewing process, including steps like mashing and fermentation, can reduce mycotoxin levels, but often does not eliminate them entirely.
Common Mycotoxin Contaminants
- Deoxynivalenol (DON): A trichothecene mycotoxin commonly found in beer, with potentially higher levels in craft beers. Ingestion is associated with gastrointestinal issues, altered nutrient absorption, and reproductive disorders.
- Ochratoxin A (OTA): Produced by Aspergillus and Penicillium molds, this mycotoxin is a possible carcinogen and can cause nephrotoxic (kidney-damaging) effects.
- Aflatoxins (AFs): Highly toxic mycotoxins, classified as Group 1 carcinogens. Aflatoxins thrive in warm, humid climates and have been found in higher concentrations in artisanal beers from certain tropical regions.
- Fumonisins (FBs): Produced by Fusarium species, fumonisins are also potentially carcinogenic and appear to a limited extent in beer, particularly when maize is used as an adjunct.
Why Craft Beer May Contain More Mycotoxins
According to some studies, craft beers may have higher mycotoxin levels than industrial beers. This can be attributed to the wider variety of raw materials used, including specific specialty grains, and sometimes different fermentation processes compared to highly standardized commercial lager production. The use of adjuncts like maize also increases the risk of fumonisin contamination.
"Forever Chemicals" (PFAS) in Brewing Water
Recent research has highlighted the presence of Per- and polyfluoroalkyl substances (PFAS), known as "forever chemicals," in beer. These industrial chemicals, which accumulate in the environment and the human body over time, enter the brewing process primarily through contaminated municipal water supplies. A study published in May 2025 found PFAS in almost every beer tested, with levels correlating to contamination in the local water used by breweries. Smaller breweries, which may lack advanced filtration systems, could be particularly susceptible. For consumers, minimizing exposure is challenging but possible by choosing breweries that prioritize water purity. The Environmental Protection Agency (EPA) is implementing new regulations, which may lead to cleaner beer in the future.
Heavy Metals: From Soil to System
Toxic heavy metals, including lead (Pb), cadmium (Cd), and arsenic (As), can infiltrate beer at various stages. Sources include contaminated soil where grains and hops are grown, and brewing equipment such as pipes, tanks, and filtration materials. High levels of heavy metals can lead to bioaccumulation and chronic health issues affecting the kidneys, nervous system, and cardiovascular health. While most regulated beers have low concentrations, the risk increases with daily, heavy consumption.
Other Contaminants and Byproducts
Pesticides
Pesticide residues from crop protection can persist on hops and grains. Studies show that different pesticides have varying transfer rates into the final beer, with solubility being a key factor. Regulations and strict agricultural practices help minimize residue, but traces can remain.
Nitrosamines
N-nitrosodimethylamine (NDMA) is a probable carcinogen that can form during the malting process, particularly when malt is heated. Modern brewing practices include testing malt for nitrosamines to control and minimize their presence.
Biogenic Amines
These organic nitrogen compounds are formed during fermentation by microorganisms and are influenced by factors like raw material quality and microbial composition. While typically present in low concentrations, high levels can have toxic effects, such as causing headaches or allergic reactions in sensitive individuals.
Packaging-Related Chemicals
- Bisphenol A (BPA): A common component in the plastic liners of cans and other packaging, BPA is an endocrine disruptor that can leach into beer over time.
- Phthalates: Used as plasticizers in various consumer products, including packaging materials, phthalates can enter beer and are associated with endocrine disruption and reproductive toxicity.
Harmful Additives and Preservatives
Many mass-produced beers contain additives that are not part of traditional brewing. Some of the most concerning include:
- High Fructose Corn Syrup and GMO Sugars: Common in many commercial beers, particularly in the U.S., which may use genetically modified corn products.
- Artificial Colors: Dyes like caramel coloring (Class III or IV) made with ammonia, as well as petroleum-based dyes like FD&C Red 40 and Yellow 5, have been linked to potential health issues.
- Sulfites: Added as a preservative to inhibit microbes and prevent oxidation. While naturally occurring in small amounts, added sulfites can trigger asthma-like symptoms or other allergic reactions in sensitive individuals.
Comparative Contaminant Risk: Industrial vs. Craft Beer
This table highlights the differences in potential contamination sources based on typical production methods.
| Feature | Industrial Beer | Craft Beer |
|---|---|---|
| Production Scale | High volume, standardized process | Smaller batches, varied ingredients |
| Water Treatment | Often advanced filtration to meet high purity standards | May rely on local municipal water, with potential for residual PFAS |
| Mycotoxin Risk | Low-to-moderate, depends on cereal sourcing and controls | Potentially higher, due to diverse specialty grains and less standardized processes |
| Additives | Higher likelihood of added ingredients like corn syrup, artificial colors, and preservatives | Varies widely; often uses more traditional ingredients, but can include exotic additions |
| Consistency | High consistency due to strict control and monitoring | More variability in both flavor and potential contaminants due to experimentation |
| Packaging | Often in cans with liners, potential for BPA/phthalate leaching | Varies (cans, bottles), some use traditional and lower-risk packaging |
Conclusion
While the primary health risk associated with beer consumption comes from ethanol itself, consumers should be aware that other harmful chemicals can be present. These include mycotoxins from contaminated grains, industrial pollutants like PFAS from brewing water, heavy metals from raw materials and equipment, and various additives or packaging-related chemicals. The overall levels in most commercially available beers are typically regulated to be low and are often not a significant health risk for moderate consumers. However, factors like the type of beer (industrial vs. craft) and the source of ingredients can influence contaminant presence. For consumers seeking to minimize exposure, supporting breweries with transparent sourcing and production practices is key. To learn more about environmental contaminants and their health effects, visit the Agency for Toxic Substances and Disease Registry.
How to Reduce Your Exposure to Beer Contaminants
- Research Breweries: Support brewers who publicly disclose ingredients and follow rigorous quality control measures.
- Choose Organic: Opt for certified organic beers, which prohibit the use of many agricultural pesticides and GMO ingredients.
- Verify Water Purity: Ask breweries about their water sourcing and filtration methods, especially if you are concerned about local water contamination like PFAS.
- Opt for Bottles: Reduce exposure to can-liner chemicals like BPA and phthalates by choosing beer in glass bottles.
- Consume in Moderation: As ethanol is the most significant health risk, limiting overall alcohol intake remains the most effective health strategy.
What are some simple steps brewers can take to minimize contaminants?
Brewers can employ a multi-pronged approach: sourcing high-quality, pre-screened raw materials (especially grains and hops), using advanced water filtration systems, maintaining strict equipment hygiene (CIP protocols), and avoiding unnecessary chemical additives or cheap corn syrup.
How does the brewing process reduce some harmful chemicals?
Certain brewing steps naturally reduce contaminants. For example, mashing and fermentation can degrade some mycotoxins like ochratoxin A, and yeast can adsorb some heavy metals and mycotoxins during fermentation. Filtration also helps remove solids and particles containing some toxins.
Is it true that some beers contain formaldehyde?
Yes, formaldehyde has been detected in some beers, though usually in very low concentrations that are unlikely to pose a significant health risk to consumers. It is classified as a human carcinogen, but exposure levels in most beverages are considered extremely low.
Do all beers contain sulfites? What are the effects?
No, not all beers contain added sulfites, though small amounts may occur naturally during fermentation. The presence of sulfites above 10 mg/L must be disclosed on the label. For individuals with sulfite sensitivity or asthma, they can trigger allergy-like symptoms like wheezing, chest tightness, and headaches.
Are artificial colors in beer dangerous?
Some artificial colors, like caramel coloring produced with ammonia (Class III/IV) or petroleum-derived dyes like FD&C Red 40, have raised health concerns. While many are regulated, transparency regarding ingredients can help consumers avoid potentially harmful additives.
Do high-gravity or stronger beers have more contaminants?
Studies suggest a correlation between higher alcohol content and elevated mycotoxin contamination, particularly DON+D3G. This is likely due to the higher volume of grain required for brewing stronger beers, increasing the risk from any contaminants present in the raw materials.
How does packaging material affect beer safety?
Packaging can introduce chemicals like BPA and phthalates, which leach from can liners and plastic closures. These endocrine disruptors can affect the body's hormonal balance. Using glass bottles or cans with non-plastic liners can help reduce this risk.
Are there contaminants unique to certain beer styles?
Yes. Mycotoxin levels can vary significantly depending on ingredients. For example, beers brewed with maize may have higher fumonisin levels, while African traditional sorghum beers can contain various mycotoxins. Some styles may also have different levels of mycotoxins based on fermentation and color.
