Cancer Risk from Arsenic in Rice & Seaweed

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A daily half-cup of cooked rice may carry a hundred times the acceptable cancer risk of arsenic. What about seaweed from the coast of Maine?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“At [some] point during the reign of King Cotton, farmers in the south central [U.S.] controlled boll weevils with arsenic-based pesticides, and residual arsenic still contaminates the soil.” Now, different plants have different reactions to arsenic exposure. For example, tomatoes don’t seem to accumulate much, but rice plants are really good at sucking it out of the ground—so much so that rice can be used for “arsenic phytoremediation,” meaning you can plant rice on contaminated land as a way to clear it from the soil, Of course, then, you’re supposed throw it and the arsenic away, but in the South, where 80% of U.S. rice is grown, we instead feed it to people.

But, national surveys have shown that most arsenic exposure has been measured coming from meat, poultry, and fish in our diet, rather than grains, but most of that is from the fish. So, if seafood is contributing 90% of our arsenic exposure from food, then why are we even talking about the 4% from rice? Because the arsenic compounds in seafood are “mainly organic”—used here as a chemistry term, nothing to do with pesticides—and organic arsenic compounds, because of the way our body can more easily deal with them, “have historically been viewed as [relatively] harmless.” Now, recently, there’ve been some questions about that assumption, but there’s no question about the toxicity of inorganic arsenic, which you can get more of from rice.

As you can see, rice contains more of the toxic inorganic arsenic than seafood, with one exception. Hijiki, an edible seaweed—a hundred times more contaminated than rice, leading some researchers to refer to it as the “so-called edible…seaweed.” Governments have started to agree. “In 2001, the Canadian [government] advised the public not to eat hijiki.” Then, the UK, the rest of Europe, Australia, New Zealand, then China “advised the public not to eat hijiki, and banned imports and sales” of the stuff. Japan, where they actually have a hijiki industry, just advised moderation.

What about Maine coast seaweed—domestic, commercially-harvested seaweed from New England? We didn’t know, until now. Thankfully, only one type had significant levels of arsenic, a type of kelp. But, it would take over a teaspoon to exceed the provisional daily limit for arsenic, and at that point, you’d be exceeding the upper daily limit for iodine by like 3,000%, ten times more than reported in this life-threatening case report attributed to a kelp supplement. So, I’d recommend to avoid hijiki due to its excess arsenic content, and avoid kelp due to its excess iodine. But all other seaweeds should be fine, as long as you don’t eat them with too much rice.

What does a number like this mean, though? 88.7 micrograms of inorganic arsenic per kilogram of raw white rice? I mean, that’s only 88.7 parts per billion. That’s like 88.7 drops of arsenic in an Olympic-size swimming pool of rice. So, how much cancer risk are we talking about? Well, just to put it in context, “[t]he usual level of acceptable risk for carcinogens is” one extra cancer case per million. That’s how we typically regulate cancer-causing substances. Whenever some industry wants to release some new chemical, we want them to show that it doesn’t cause more than one in a million excess cancer cases. Now, we have 300 million people in this country; so, that doesn’t make the 300 extra people who get cancer feel any better, but you have to cut it off somewhere. Okay.

The problem with arsenic in rice is that the excess cancer risk associated with eating just about a half-cup of cooked rice a day could be closer to one in 10,000. That’s a hundred times the acceptable cancer risk. The FDA has calculated that one serving a day of the most common rice, long grain white, would cause not one in a million extra cancer cases, but 136 in a million.

And, that’s just the cancer effects of arsenic. What about all the non-cancer effects? The “FDA acknowledges that, in addition to cancer, [the toxic] arsenic [found in rice] has been associated with many non-cancer effects, including…heart disease, diabetes, skin lesions, [kidney] disease, hypertension, and stroke.” The only reason they just stuck to calculating the cancer risks is that assessing all the other risks would take a lot of time, and that “would delay taking any needed action to protect [the public’s] health” from the risks of rice.

Yes, “physicians can help patients reduce their dietary arsenic exposure, [but] regulatory agencies, food producers, and legislative bodies have the most important roles” in terms of public health scale changes. “[A]rsenic content in US-grown rice has been relatively constant throughout the last 30 years,” which is a bad thing.

“Where[ver]…arsenic concentration is elevated due to ongoing contamination, the ideal scenario is to stop the contamination at the source.” Some toxic arsenic in foods is from natural contamination of the land, but soil contamination has also come from dumping arsenic-containing pesticides, “and the use of arsenic-based drugs in poultry production,” and then spreading the arsenic-laced chicken manure on the land. Regardless of why Southern rice paddies are so contaminated, maybe we shouldn’t be growing rice in arsenic-contaminated soil.

What does the rice industry have to say for itself? Well, they started a website, called ArsenicFacts, no less. Always got to be skeptical of any group that claims “facts” in their title; *ahem*. Their main argument appears to be, look, arsenic is everywhere; we’re all exposed to it every day. It’s in most foods. So, what, we shouldn’t try to cut down on the most concentrated sources? Isn’t that like saying, look, diesel exhaust is everywhere; so, why not suck on a tailpipe? They quote some nutrition professor saying, look, all foods have a little bit. So, eliminating arsenic would decrease your risk a little bit, but you’d die of starvation. That’s like Philip Morris saying look, the only way you’re going to completely avoid secondhand smoke in your life is to never breathe—and then you’d asphyxiate; so, might as well just start smoking yourself. If you can’t avoid it, you might as well consume the most toxic source you can find.

That’s the same tack the poultry industry took. Arsenic & chicken? No need to worry, because there’s a little arsenic everywhere. See? So, that’s why it’s okay that we fed our chickens arsenic-based drugs for 70 years. If you can’t beat ‘em, join ‘em.

Please consider volunteering to help out on the site.

Motion graphics by Avocado Video. 

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“At [some] point during the reign of King Cotton, farmers in the south central [U.S.] controlled boll weevils with arsenic-based pesticides, and residual arsenic still contaminates the soil.” Now, different plants have different reactions to arsenic exposure. For example, tomatoes don’t seem to accumulate much, but rice plants are really good at sucking it out of the ground—so much so that rice can be used for “arsenic phytoremediation,” meaning you can plant rice on contaminated land as a way to clear it from the soil, Of course, then, you’re supposed throw it and the arsenic away, but in the South, where 80% of U.S. rice is grown, we instead feed it to people.

But, national surveys have shown that most arsenic exposure has been measured coming from meat, poultry, and fish in our diet, rather than grains, but most of that is from the fish. So, if seafood is contributing 90% of our arsenic exposure from food, then why are we even talking about the 4% from rice? Because the arsenic compounds in seafood are “mainly organic”—used here as a chemistry term, nothing to do with pesticides—and organic arsenic compounds, because of the way our body can more easily deal with them, “have historically been viewed as [relatively] harmless.” Now, recently, there’ve been some questions about that assumption, but there’s no question about the toxicity of inorganic arsenic, which you can get more of from rice.

As you can see, rice contains more of the toxic inorganic arsenic than seafood, with one exception. Hijiki, an edible seaweed—a hundred times more contaminated than rice, leading some researchers to refer to it as the “so-called edible…seaweed.” Governments have started to agree. “In 2001, the Canadian [government] advised the public not to eat hijiki.” Then, the UK, the rest of Europe, Australia, New Zealand, then China “advised the public not to eat hijiki, and banned imports and sales” of the stuff. Japan, where they actually have a hijiki industry, just advised moderation.

What about Maine coast seaweed—domestic, commercially-harvested seaweed from New England? We didn’t know, until now. Thankfully, only one type had significant levels of arsenic, a type of kelp. But, it would take over a teaspoon to exceed the provisional daily limit for arsenic, and at that point, you’d be exceeding the upper daily limit for iodine by like 3,000%, ten times more than reported in this life-threatening case report attributed to a kelp supplement. So, I’d recommend to avoid hijiki due to its excess arsenic content, and avoid kelp due to its excess iodine. But all other seaweeds should be fine, as long as you don’t eat them with too much rice.

What does a number like this mean, though? 88.7 micrograms of inorganic arsenic per kilogram of raw white rice? I mean, that’s only 88.7 parts per billion. That’s like 88.7 drops of arsenic in an Olympic-size swimming pool of rice. So, how much cancer risk are we talking about? Well, just to put it in context, “[t]he usual level of acceptable risk for carcinogens is” one extra cancer case per million. That’s how we typically regulate cancer-causing substances. Whenever some industry wants to release some new chemical, we want them to show that it doesn’t cause more than one in a million excess cancer cases. Now, we have 300 million people in this country; so, that doesn’t make the 300 extra people who get cancer feel any better, but you have to cut it off somewhere. Okay.

The problem with arsenic in rice is that the excess cancer risk associated with eating just about a half-cup of cooked rice a day could be closer to one in 10,000. That’s a hundred times the acceptable cancer risk. The FDA has calculated that one serving a day of the most common rice, long grain white, would cause not one in a million extra cancer cases, but 136 in a million.

And, that’s just the cancer effects of arsenic. What about all the non-cancer effects? The “FDA acknowledges that, in addition to cancer, [the toxic] arsenic [found in rice] has been associated with many non-cancer effects, including…heart disease, diabetes, skin lesions, [kidney] disease, hypertension, and stroke.” The only reason they just stuck to calculating the cancer risks is that assessing all the other risks would take a lot of time, and that “would delay taking any needed action to protect [the public’s] health” from the risks of rice.

Yes, “physicians can help patients reduce their dietary arsenic exposure, [but] regulatory agencies, food producers, and legislative bodies have the most important roles” in terms of public health scale changes. “[A]rsenic content in US-grown rice has been relatively constant throughout the last 30 years,” which is a bad thing.

“Where[ver]…arsenic concentration is elevated due to ongoing contamination, the ideal scenario is to stop the contamination at the source.” Some toxic arsenic in foods is from natural contamination of the land, but soil contamination has also come from dumping arsenic-containing pesticides, “and the use of arsenic-based drugs in poultry production,” and then spreading the arsenic-laced chicken manure on the land. Regardless of why Southern rice paddies are so contaminated, maybe we shouldn’t be growing rice in arsenic-contaminated soil.

What does the rice industry have to say for itself? Well, they started a website, called ArsenicFacts, no less. Always got to be skeptical of any group that claims “facts” in their title; *ahem*. Their main argument appears to be, look, arsenic is everywhere; we’re all exposed to it every day. It’s in most foods. So, what, we shouldn’t try to cut down on the most concentrated sources? Isn’t that like saying, look, diesel exhaust is everywhere; so, why not suck on a tailpipe? They quote some nutrition professor saying, look, all foods have a little bit. So, eliminating arsenic would decrease your risk a little bit, but you’d die of starvation. That’s like Philip Morris saying look, the only way you’re going to completely avoid secondhand smoke in your life is to never breathe—and then you’d asphyxiate; so, might as well just start smoking yourself. If you can’t avoid it, you might as well consume the most toxic source you can find.

That’s the same tack the poultry industry took. Arsenic & chicken? No need to worry, because there’s a little arsenic everywhere. See? So, that’s why it’s okay that we fed our chickens arsenic-based drugs for 70 years. If you can’t beat ‘em, join ‘em.

Please consider volunteering to help out on the site.

Motion graphics by Avocado Video. 

Doctor's Note

How can the rice industry get away with selling a product containing a hundred times the acceptable cancer risk? I cover that and so much more in my other videos on arsenic and rice, which also include concrete recommendations on how to mediate your risk.

Check out:

Pesticides were not the only source of arsenic. Poultry poop, too, if you can believe it! I cover that story in Where Does the Arsenic in Chicken Come From? and Where Does the Arsenic in Rice, Mushrooms, and Wine Come From?.

Chronic low-dose arsenic exposure is associated with more than just cancer. See The Effects of Too Much Arsenic in the Diet.

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