Your Cup of Coffee Might Come With a Cancer Warning
Calfornia coffee shops may soon be forced to warn customers about a possible cancer risk linked to their morning jolt of java.
The state keeps a list of chemicals it considers possible causes of cancer, and one of them, acrylamide, is created when coffee beans are roasted.
What is acrylamide?
Acrylamide is a chemical used primarily to make substances called polyacrylamide and acrylamide copolymers. Polyacrylamide and acrylamide copolymers are used in many industrial processes, such as the production of paper, dyes, and plastics, and in the treatment of drinking water and wastewater, including sewage. They are also found in consumer products, such as caulking, food packaging, and some adhesives.
Acrylamide is also found in some foods. It can be produced when vegetables that contain the amino acid asparagine, such as potatoes, are heated to high temperatures in the presence of certain sugars (1, 2). It is also a component of tobacco smoke.
How are people exposed to acrylamide?
Food and cigarette smoke are the major sources of acrylamide exposure for people in the general population (3, 4).
The major food sources of acrylamide are French fries and potato chips; crackers, bread, and cookies; breakfast cereals; canned black olives; prune juice; and coffee.
Acrylamide levels in food vary widely depending on the manufacturer, the cooking time, and the method and temperature of the cooking process (5, 6). Decreasing cooking time to avoid heavy crisping or browning, blanching potatoes before frying, not storing potatoes in a refrigerator, and post-drying (drying in a hot air oven after frying) have been shown to decrease the acrylamide content of some foods (7, 8).
People are exposed to substantially more acrylamide from tobacco smoke than from food. People who smoke have three to five times higher levels of acrylamide exposure markers in their blood than do non-smokers (9). Exposure from other sources is likely to be significantly less than that from food or smoking, but scientists do not yet have a complete understanding of all sources of exposure. Regulations are in place to limit exposure in workplaces where acrylamide may be present, such as industrial settings that use polyacrylamide and acrylamide copolymers.
Is there an association between acrylamide and cancer?
Studies in rodent models have found that acrylamide exposure increases the risk for several types of cancer (10–13). In the body, acrylamide is converted to a compound called glycidamide, which causes mutations in and damage to DNA. However, a large number of epidemiologic studies (both case-control and cohort studies) in humans have found no consistent evidence that dietary acrylamide exposure is associated with the risk of any type of cancer (9, 14). One reason for the inconsistent findings from human studies may be the difficulty in determining a person’s acrylamide intake based on their reported diet.
The National Toxicology Program’s Report on Carcinogens considers acrylamide to be reasonably anticipated to be a human carcinogen, based on studies in laboratory animals given acrylamide in drinking water. However, toxicology studies have shown that humans and rodents not only absorb acrylamide at different rates, they metabolize it differently as well (15–17).
Studies of workplace exposure have shown that high levels of occupational acrylamide exposure (which occurs through inhalation) cause neurological damage, for example, among workers using acrylamide polymers to clarify water in coal preparation plants (18). However, studies of occupational exposure have not suggested increased risks of cancer (19).
Are acrylamide levels regulated?
The U.S. Environmental Protection Agency (EPA) regulates acrylamide in drinking water. The EPA established an acceptable level of acrylamide exposure, set low enough to account for any uncertainty in the data relating acrylamide to cancer and neurotoxic effects. The U.S. Food and Drug Administration regulates the amount of residual acrylamide in a variety of materials that contact food, but there are currently no guidelines governing the presence of acrylamide in food itself.
What research is needed to better understand whether acrylamide is associated with cancer in people?
Additional epidemiologic studies in which acrylamide adduct or metabolite levels are serially measured in the same individuals over time (longitudinal cohorts) are needed to help determine whether dietary acrylamide intakes are associated with increased cancer risks in people. It is also important to determine how acrylamide is formed during the cooking process and whether acrylamide is present in foods other than those already tested. This information will enable researchers to make more accurate and comprehensive estimates of dietary exposure. Biospecimen collections in cohort studies will provide an opportunity to examine biomarkers of exposure to acrylamide and its metabolites in relation to the subsequent risk of cancer.