Why Does Nori have a Cancer Warning?

May 2, 2023
4 min read

Have you ever noticed a warning label on your favorite sushi rolls? If you have, you might have wondered why nori, the seaweed used to wrap sushi, has a cancer warning. Nori is a staple in Japanese cuisine and is also enjoyed by many worldwide. However, the cancer warning has raised concern among some consumers. In this blog post, we will explore the reasons behind this warning and whether nori is safe to consume.

What is Nori?

Nori is a type of edible seaweed that is commonly used in sushi rolls. It is a thin, dried sheet that has a crispy texture and a slightly salty flavor. Nori is made from a variety of red algae called Porphyra, which is native to Japan and other parts of the Pacific. In Japan, nori has been consumed for centuries and is an essential ingredient in many dishes.

Today, nori is widely available in grocery stores and used in many ways. Besides sushi rolls, nori is also used as a garnish, added to soups, or eaten as a snack. Nori is not only delicious but also has many health benefits. It is rich in vitamins and minerals such as iodine, calcium, and iron, and is also a good source of protein and dietary fiber.

So, why does nori have a cancer warning label? To understand this, we must look at the potential risks of consuming nori.

Nori and Arsenic

Arsenic is a naturally occurring element that is found in soil, water, and air. It is also present in some types of seafood, including seaweed. Arsenic is a known carcinogen, which can cause human cancer. The level of arsenic in seaweed varies depending on the species and where it is grown.

In 2012, a study conducted by researchers at the University of California, Berkeley found that some types of seaweed, including nori, contained high levels of arsenic. The study analyzed seaweed samples from various countries and found that some samples had up to 180 parts per billion (ppb) of arsenic. The US Environmental Protection Agency (EPA) has set a limit of 10 ppb of arsenic in drinking water. However, there are no specific limits for arsenic in food.

While the study raised concerns about the safety of consuming seaweed, it is important to note that the levels of arsenic found in the seaweed samples were still within the safe range. The FDA has not set any limits for arsenic in seaweed, but they do monitor the levels of arsenic in food and take action if necessary.

Nori and Polycyclic Aromatic Hydrocarbons (PAHs)

Polycyclic Aromatic Hydrocarbons (PAHs) are chemicals that are formed when organic matter is burned. They are also present in cigarette smoke and car exhaust. PAHs can cause human cancer and have been linked to various health problems.

PAHs can be found in many foods, including grilled meats, smoked fish, and some types of seaweed. When seaweed is dried and roasted to make nori, it can form PAHs. In a study conducted by researchers at the National University of Ireland, Galway, they found that some types of nori had high PAH levels.

While the PAH levels in nori are a cause for concern, it is important to note that the levels are still within the safe range. The FDA has not set any specific limits for PAHs in food, but they do monitor the levels of PAHs in food and take action if necessary.


In conclusion, nori has a cancer warning label due to the potential risks associated with consuming it. Nori can contain high levels of arsenic and polycyclic aromatic hydrocarbons (PAHs), which are both known carcinogens. However, the levels of these chemicals in nori are still within the safe range. It is important to consume nori in moderation and to choose high-quality nori that is sourced from reputable suppliers. If you have concerns about consuming nori, it is best to consult with your healthcare provider.

Leave a Reply

Your email address will not be published. Required fields are marked *