Studies show that some dark chocolates are high in cadmium and lead. Do we need to worry?
Posted at 12:00 p.m
an ounce
Last December, the verdict came down: 23 of the 28 most popular brands of dark chocolate in the United States contained cadmium – a toxic metal – above California standards. According to an analysis by the American group Consumer Reports, these are the strictest standards.
PHOTO FROM UNIVERSITY OF CONNECTICUT WEBSITE
Melissa Melough during her PhD at the University of Connecticut
“Dark chocolate is one of the foods with the most cadmium when you factor in normal consumption,” says Melissa Melough of the University of Delaware, who published a 2018 estimate of dietary cadmium sources in the journal Nutrients in the United States. “The FDA estimated in 2018 that an ounce (just under 30g) of dark chocolate contained an average of 7.6 micrograms of cadmium, while the California limit is 4.1 micrograms per day. The Delaware epidemiologist calculated in 2018 that the average American ingests five micrograms of cadmium daily with meals.
The Consumer Reports study also reported that 5 of the 28 dark chocolate bars studied exceeded lead standards. But according to Ms. Melough, there are wide variations in exposure to lead from paints that contained it up until the late 1970s. The limit for lead in California is 0.5 micrograms per day. A 2020 study published in the journal Food Research International estimates that a normal diet contains 10 micrograms of lead per day.
Driven
According to Martin Laliberté, emergency physician and toxicologist at McGill University Health Center (MUHC), the dangers of cadmium and lead primarily affect children, and by extension pregnant women, as their brains and organs develop. “I wouldn’t worry parents about the chocolate thing though. There’s cadmium and lead in other foods,” says Dr. Laliberte. Ms Melough points out that milk chocolate contains far less cadmium. “It’s the cocoa powder that it contains,” she says. The FDA also estimated that the two foods that contained the most were cocoa and baking soda. But obviously we consume very little per day. »
PHOTO VINCENZO PINTO, AGENCE FRANCE PRESS ARCHIVE
Milk chocolate contains much less cadmium than dark chocolate.
Health problems related to cadmium – kidney and lung problems – were first observed in industrial workers, whose blood levels were 50 to 200 times higher than those of the general population. However, a 2010 study published in the journal BMC Public Health that analyzed data from 5,000 Americans who were followed for 20 years found that kidney problems can occur with high intakes of cadmium. hardly two to four times higher than the population average. Cadmium is converted in the liver into a molecule that damages the kidney tubules.
In particular, lead exposure in early childhood has been associated with problems in brain development.
Chocolate versus…
Curiously, vegetarians eat twice as much cadmium as the average population because nuts and grains contain more of it than average foods, according to a 2009 report by the European Food Safety Authority (EFSA). contain the most cadmium, but it all depends on the amount consumed,” says Ms. Melough. For example, you’d have to eat two-thirds of a cup of spinach a day to cross the California border, or five tablespoons of peanut butter. »
The reasons
PHOTO GETTY IMAGES
Cacao nibs are sometimes exposed to cadmium and lead during drying.
Cadmium and lead in food come from the soil and air. “In some areas there is more cadmium in the soil and the cocoa trees take up this cadmium along with other soil nutrients,” says Ms. Melough. Cocoa beans are also air dried, exposing them to cadmium and lead dust from traffic and industry. A 2020 study published in the Journal of Agricultural and Food Chemistry by FDA researchers found that cocoa from certain regions of Latin America contains more cadmium and lead than cocoa from Africa, which accounts for 75% of world production.
Parried
The 2020 FDA study mentioned that pilot projects in Trinidad and Tobago were successful in reducing the amount of cadmium in cocoa by raising the pH of soils with lime (making them less acidic) because the cadmium from cocoa trees is over is less well absorbed at a pH of 6. The same pilot projects mixed charcoal with the soils because it binds to the cadmium and makes it unavailable to the trees. Another pilot project in Peru showed that reducing the use of chemical fertilizers in cocoa plantations reduced cadmium levels in cocoa. There are several reasons for this: Fertilizers contain cadmium and they acidify the soil. With less fertilizer, cacao trees grow more slowly, which reduces uptake of cadmium along with other nutrients.
Other norms
The federal standards of the US, Canada and EFSA offer a different approach: the limits for the intake of cadmium in the diet are linked to a person’s weight. “This makes the limit much lower for children than for adults and for women than for men,” says Ms. Melough. These limits are 0.8 micrograms per pound of bodyweight per day in Canada, 0.1 micrograms per pound of bodyweight per day in the United States (CDC) and 2.5 micrograms per pound of bodyweight per week in Europe (EFSA). “For a person weighing 130 pounds, the US federal limit is slightly higher than that in California. In Europe, the limit is four times higher,” says Ms. Melough. The Canadian limit for cadmium is ten times higher than the California limit.
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0.33 micrograms per liter Average level of cadmium in the blood of a Canadian in 2007-2009
Source: Health Canada
0.27 micrograms per liter Average amount of cadmium in the blood of a Canadian in 2018-2019
Source: Health Canada
5 times the amount of cadmium in the blood of a smoker compared to a non-smoker
Source: Health Canada