Cassava Flour, Chips, Bread, and More Contain High Levels of Lead
Cassava has become a popular gluten-free alternative, but CR’s tests of 27 products found that more than two-thirds of them contain more lead in a single serving than our experts say you should have in a day
You’ve probably seen products made with cassava in the supermarket, especially if you’ve looked at gluten-free or paleo-friendly foods. The starchy root vegetable—aka yuca or manioc—has long been a dietary staple in parts of the Caribbean, Africa, South Asia, and South America. But recently, it’s gained a reputation as a health food, touted for its grain-free and gut-health properties. As a result, cassava flour is being used more and more in a variety of foods, such as bread, pasta, chips, and cookies.
If you’ve been thinking about giving cassava products a try, though, you need to carefully consider the options. Consumer Reports’ latest tests of 27 products found that for over two-thirds of them, a single serving exceeded the level of lead Consumer Reports’ food safety experts use as a threshold for an acceptable daily intake—some by more than 2,000 percent. CR has tested several categories of foods and spices for heavy metals. With the exception of some spices (for example, certain brands of basil, cinnamon, ginger, thyme, and turmeric), "we’ve never seen lead levels as high as those we found in some of these cassava foods,” says James E. Rogers, PhD, director of product and food safety research and testing at Consumer Reports.
This new cassava-foods investigation followed CR’s 2024 tests of veggie puffs that are marketed as healthy snacks for young children. There, we found that some cassava-containing puffs had the highest lead levels of any baby food CR has tested since 2017.
“Together, these results show that there is a real reason for consumers to be concerned about lead in foods that contain cassava,” Rogers says.
The Problem With Lead
Lead is found in soil. It’s naturally part of the earth’s crust, but it can also be deposited in the ground from industrial pollution and the use of leaded gasoline or lead-based pesticides and remain there for years.
You can come into contact with small amounts of lead in a variety of ways—through food, contaminated drinking water, or environmental sources such as lead-based paint, for example. With regular exposure, these small amounts can add up over time, accumulating in the body and raising the chances of health problems.
The risks are greatest during childhood and pregnancy because lead can damage the brain and nervous system in young children and developing fetuses. This has the potential to cause learning and behavior problems, and more. In adults, frequent lead exposure has been linked to immune system suppression, reproductive issues, kidney damage, and hypertension.
When assessing how much lead might cause actual harm, it’s first important to note that “epidemiologists have yet to find a level of lead exposure without some risk,” says Keeve Nachman, PhD, a professor of environmental health and engineering at the Johns Hopkins Bloomberg School of Public Health in Baltimore. But the effects of small amounts can be difficult to detect. While a high dose of lead can cause symptoms ranging from stomach pain and headache to seizures or coma, trace exposure is more subtle, he says, “manifesting as increased rates of certain neurological effects and slight downward shifts in IQ in the population.”
That said, total avoidance of lead is not possible, Nachman says. “It is not highly unusual that foods that are a normal part of our diets will occasionally put people over the daily exposure limits,” he said in reference to established federal and state levels.
The Trouble With Cassava
Root vegetables—including cassava, carrots, beets, and sweet potatoes—grow in the ground and are known to take up some lead along with other heavy metals and contaminants. There’s nothing about the cassava plant that should make it more likely than other root vegetables to absorb lead, according to Ganga Hettiarachchi, PhD, a professor of soil and environmental chemistry who studies trace metal and nutrient chemistry at Kansas State University in Manhattan. But it is possible that some cassava could be grown in highly polluted areas, or handled or processed in ways that introduce lead, she says.
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Several studies have found that cassava can be a significant dietary source of lead exposure in people who eat it frequently. For example, in a 2015 study in the International Journal of Environmental Research and Public Health, researchers found that cassava grown in one region of Ghana was high enough in lead to raise the risk of health problems among people who ate it regularly.
“In Ghana [this contamination] tends to be a problem because we consume a lot of cassava. It’s our staple,” says Nesta Bortey-Sam, PhD, an assistant professor of chemical and environmental toxicology at the University of Pittsburgh School of Public Health, and an author of the study. But, he says, the levels in products that had the most lead in CR’s tests were comparable to the lead levels in the cassava in the study. (CR is exploring follow-up testing of cassava products used in African, Asian, and Caribbean communities in the U.S.)
In another study, published in the Journal of Toxicology and Environmental Health in 2013, researchers measured the amount of lead in manioc (cassava) flour used as a staple food in several remote communities in the Amazon. They found that the levels in the flour were far higher than those in the fresh root. Blood lead levels in these communities were, on average, nearly four times higher than the levels that raise red flags when detected by pediatricians in the U.S.
Rubin, the owner of Lead Safe Mama, says that her organization has found high lead levels in several cassava products in its testing. She also says cassava has emerged as a significant source of lead in some families that Lead Safe Mama has worked with.
“In working with families to identify sources of their child’s lead exposure, we first rule out the ‘usual suspects’ [lead-contaminated paint, soil, and water], before moving on to consider dietary sources,” Rubin says. “In nearly every case I have investigated in which we have narrowed the likely source of lead exposure down to dietary sources, cassava has played a significant role in that family’s diet.”
One such parent, Audrey Powell of Austin, Texas, says that back in 2022, her family had been trying to resolve some mysterious health issues their 4-year-old daughter was experiencing. A doctor recommended lead testing; the results showed slightly elevated levels.
As she tried to identify the source of the lead, Powell contacted Rubin, who made several recommendations for areas to check. “We tested our whole house, the paint, the soil in our yard, the water,” Powell says. “It was very frightening.” When those results didn’t provide conclusive answers, she ended up sending a variety of foods the family ate regularly to a private company for heavy metal testing. One of those foods was cassava flour, which Powell had switched to, believing it was a healthy choice. That flour came back with a result that’s nearly three times as high as any of the products in CR’s current tests.
Immediately, Powell stopped using the flour, and made several other changes Rubin advised, like replacing the toothpaste and some of the pans she used. The next time they tested her daughter’s lead level, it had dropped, Powell says. Since then, she has been growing well and is much healthier.
What CR's Tests Found
For CR’s latest tests, our scientists selected a wide range of foods that included cassava as a primary ingredient—chips, flours, crackers, breads, cookies, a bar, a cereal, a pasta, a puff snack, and a soda. We tested for several heavy metals—arsenic, cadmium, lead, and mercury. For details on our testing methods, see our methodology sheet (PDF).
Lead was the only heavy metal that emerged as an issue. We did not detect mercury in any product. And while we found measurable levels of arsenic in about half of the foods we tested and cadmium in most of them, the amounts in one serving of the products were far below CR’s levels of concern for those metals.
Although there were some exceptions, in general cassava flour and products made with it had the highest levels of lead. Some of the products contained tapioca starch (also called tapioca flour) or tapioca syrup, which are ingredients derived from cassava. Products with these ingredients (alone or in combination with cassava flour) tended to have lower lead levels. (Tapioca is used to make a wide range of foods, including “boba,” the balls used in bubble tea.) This may be because cassava flour is made by drying and grinding the whole, fresh, peeled root, and that process could potentially concentrate any lead that may have been in the vegetable, says Eric Boring, PhD, a CR chemist who co-led our testing. Tapioca starch is extracted from the root through washing and pulping, and tapioca syrup is made by processing the starch. Products that listed cassava flour as just one of several flours in the ingredients list also tended to be lower in lead.
Of the seven cassava flours in our tests, four had lead levels so high that our experts advise you not to consume them. A ¼-cup serving per day contained between 1,000 and more than 2,300 percent of CR’s level of concern for lead, which is 0.5 micrograms. The others had between 200 and just over 600 percent of that level per serving. These should be limited, but they’re okay to eat occasionally. The flour with the lowest lead levels in our tests is Tonomi Cassava Flour; one serving supplies 215 percent of CR’s level of concern. Our experts say it’s okay to have up to three servings of it per week.
Of course, no one eats flour (cassava or otherwise) straight. Still, when we reviewed several recipes for baked goods made with cassava flour, we saw that consuming that ¼ cup in one sitting isn’t difficult. For example, recipes that yield 12 muffins call for 1½ to 1⅔ cups of cassava flour. That means that 2 muffins would supply about ¼ cup.
Cassava chips also had high lead levels in our tests. Of the eight products we looked at, two are on our avoid list, and one had lead levels high enough that our experts advise eating no more than one serving per week. The lead levels in an ounce of these three products ranged from about 600 to 1,700 percent of CR’s level of concern. The chips with the lowest lead levels were Goya Yuca Cassava Chips. An ounce supplied 10 percent of CR’s level of concern for lead (see chart below).
Lead in Cassava Products
CR tested 27 foods and ingredients made with cassava—or cassava-derived ingredients such as tapioca starch or cassava syrup—for lead. The results are shown below as a percentage of CR’s level of concern for lead in one serving of the food.
This level is based on the California Proposition 65 maximum allowable dose level (MADL) for lead (0.5 micrograms per day). Our experts use this value because it is the most protective lead standard available.
Under Prop 65 regulations for lead or other substances that are “known to the state of California” to cause birth defects or other reproductive harm, products that exceed the MADL must carry a warning label.
Unlike Prop 65, which takes into consideration consumers’ average exposure over time and dietary frequency to calculate whether a product exceeds the MADL and requires a warning label, Consumer Reports assumes one serving a day of the product in its risk assessment calculations. This difference in methodology means no Prop 65 judgments can be made from CR’s findings. Our results are meant to provide guidance on which products have comparatively higher levels of lead, not to identify the point at which lead exposure will have measurable harmful health effects, or to assess compliance with California law. For more information, see our testing methodology sheet (PDF).
Based on our findings, we have organized the products into three categories. For those in Products to Avoid, the lead content far exceeded CR’s level of concern. Other products are categorized as Okay to Eat Occasionally and Better Choices, and we list the maximum number of servings you could have per week or per day without exceeding CR’s level of concern.
Chart Footnotes
1. Carries a California Prop 65 warning label on the package or on the product website.
2. This product has been discontinued by the manufacturer, but consumers may still have this product in their pantries.
3. The manufacturer originally told CR that based on its own testing, it had temporarily stopped selling this product while it conducted further tests. After publication, it said it had discontinued the product. Consumers may still have this product in their pantries.
4. The manufacturer said it reformulated this product in February 2025 and it no longer contains cassava; we purchased the products for our tests before the reformulation. Consumers may still have this product in their pantries.
5. While one serving of this product did not exceed our level of concern for cadmium, the cadmium content did influence the serving size recommendation.
Cassava Companies Respond
We contacted the 18 manufacturers with products that exceeded CR’s level of concern for lead, sending them our test results and asking for comment. We received responses from nine of them: Bob’s Red Mill, Iberia, Lesser Evil, MadeGood, Otto’s Naturals, Pamela’s, Terrasoul, Thrive Market, and Whole Foods.
Many said that lead is a naturally occurring element that cannot be fully avoided. MadeGood, Otto’s Naturals, and Thrive said that they test their ingredients or finished products for heavy metals.
Iberia said that currently it does not “test every batch of raw ingredients prior to use” but periodically tests the finished products and takes additional precautions, such as sourcing ingredients from low-contamination regions. The company sent test results for three lots of its product, which were produced after the lots we tested. These showed lower levels of lead than what we found. However, for at least two of the lots the levels would still be above CR’s level of concern, and our scientists said that the company used a different testing methodology from the one we used.
A few companies said that the products we tested have since been discontinued. (These are marked with a footnote in our chart.) We included them in our results because these foods have a long shelf life and consumers may still have them in their pantries.
Some of the companies acknowledged that concerns about cassava played a role in their decision to stop selling their product.
Thrive Market, whose cassava chips had high levels of lead, said: “We conducted an internal audit of our Thrive Market brand food assortment, focused specifically on heavy metal testing. That audit identified the same cassava chip product for further testing, and we have subsequently removed the product from our site while all testing is completed.” After this article was published, Thrive informed us that it had discontinued these chips.
MadeGood said that the Star Puffed Crackers CR tested were from a batch produced before the company made changes in the product’s formula. After identifying “a cassava ingredient that was outside our stringent specifications,” MadeGood said it first reduced the amount of cassava in the crackers and then “determined that reformulation to eliminate cassava completely was the best permanent solution.”
Lesser Evil said that it stopped making its No Cheese Cheesiness Paleo Puffs “in response to shifting consumer preferences towards other puff products in our lineup” but also said that, separately, it has transitioned away from using cassava across its portfolio.
After publication, Jovial contacted CR and said that the company’s testing showed lower lead levels when the noodles were cooked. CR tested all cassava products out of the package.
Warnings on Cassava Product Labels
Bob’s Red Mill and Pamela’s noted that their products’ packaging carried a Prop 65 warning label, and thus consumers were appropriately notified. We saw those warnings in our review of all the products, and found eight others that had them on the product package or on the company’s website. (We note which products do so in our chart.)
Photo: Consumer Reports Photo: Consumer Reports
Prop 65 levels have a safety margin built in. For substances that can cause reproductive issues, it is 1/1000 of the level at which there were no observable effects in animal studies. “It is the strictest standard out there,” CR’s Rogers says. “And since no level of lead exposure is safe, we believe that it’s wise to be conservative.”
“Putting a Prop 65 warning label on a product does alert consumers to a potential problem, but what would be better is if a company makes every effort to source their ingredients from areas where lead levels are low enough to make a warning unnecessary,” says Brian Ronholm, director of food policy at CR. “That’s why we are calling on the manufacturers whose products contained the most lead in our tests—Bob’s Red Mill, Jovial, Otto’s Naturals, and Quay—to do just that. The variation in lead levels among products of the same type in our tests shows that it’s possible to produce cassava products with lower levels of lead.” (Sign our petition.)
And while the levels based on California’s are the most health protective, they aren’t the only way to evaluate the amount of lead in a food. One daily serving of the 10 products with the highest lead levels in our test would exceed the Food and Drug Administration’s interim reference level (IRL) for lead in food for children. The three at the top of the list surpassed the IRL for women of childbearing age. These levels (2.2 micrograms per day and 8.8 micrograms per day, respectively) “serve as a benchmark to evaluate whether lead exposure from food is a potential concern,” according to the agency.
The FDA’s IRL levels, which were updated in 2022, are not based on a “safe” level, but are meant to flag foods that could put people’s blood lead levels in the top 2.5 percent of the population.
Like the MADL, the FDA IRL includes a safety margin. In this case it is 10 times the level, meaning that it would take 10 times the IRL to hit the blood lead levels of concern. The buffer helps account for the fact that some people absorb lead from food more than others, according to Maya Deyssenroth, DrPH, an assistant professor of environmental health sciences at Columbia University’s Mailman School of Public Health. Plus, it’s important to remember that people are also exposed to lead from other sources, including other foods, water, dust, and soil.
We sent our test results to the FDA and asked how it monitors heavy metal levels in cassava. A spokesperson said: “The FDA maintains its Toxic Elements Compliance Program to ensure regular post-market surveillance of foods that are most likely to have potential for toxic element contamination, given environmental conditions, and therefore most likely to contribute to the human exposure of toxic elements. Included in that surveillance monitoring program are cassava-based food products—including bread, chips, fries, flour, and starch—as well as whole cassava. If FDA finds that the level of a contaminant in a food causes the food to be unsafe, we take action, which may include working with the manufacturer to resolve the issue and taking steps to prevent the product from entering or remaining in the U.S. market.”
Advice for Consumers
There are several things you can do to minimize the lead in your diet (and its potential effects) from cassava products and other sources.
Limit exposure. If you are going to consume products that contain cassava, you can reduce your lead exposure by limiting the number of servings you have each week, and avoiding products with the highest levels, says Sana Mujahid, PhD., manager of food safety research and testing at Consumer Reports, who co-led our tests. This is especially important for children and people who are pregnant or who could become pregnant.
Consider other gluten-free options. If you need to follow a gluten-free diet, cassava isn’t your only choice. Buckwheat, corn, and millet are also gluten-free, and based on CR’s past testing, should be much lower in lead than cassava flour. These are also low in arsenic and cadmium. Other research shows that sorghum is lower in arsenic, cadmium, and lead. Rice is low in lead and cadmium, although it can be high in arsenic. CR’s recommendation is to mix it up. We have also identified some cassava-based products that you can eat more regularly.
Vary your diet. Including a variety of healthy foods in your diet in general can help you avoid overconsumption of heavy metals. And getting enough of certain nutrients, such as calcium, iron, selenium, vitamin C, and zinc, may help offset some of the harm heavy metals do in the body. “Dietary variety is a great way to ensure that you are getting the benefits of a balanced diet while avoiding excessive lead intake from any one type of food,” says Nachman at Johns Hopkins. The FDA echoed this advice to vary your diet in its response back to CR.
Clean and peel. If you normally consume whole cassava as a vegetable, know that some research shows that in cassava plants from sites with high lead in soil, much of the lead is concentrated in the outer layers of the root. Carefully cleaning and fully peeling the vegetable could reduce the amount of lead in fresh cassava root.
Consider testing your drinking water. In some areas, drinking water has elevated levels of lead. Most people on municipal water who pay their own bill should receive an annual water quality report called a CCR, or Consumer Confidence Report. If you don’t receive yours, call your local water supplier. And if you rent, contact your landlord. Systems that serve 100,000 or more people must also post reports online. You can find them on the Environmental Protection Agency website. However, those reports don’t account for lead that may get into your water from the pipes in your home, and people on well water won’t get a CCR. You might want to send a sample of your drinking water to a certified lab for testing. National Testing Laboratories and Tap Score both performed well in CR’s tests.
Editor’s Note: This article was updated to include feedback that Thrive and Jovial provided after publication.