cadmium

Dark chocolate is not so dangerous

July 15, 2024 By EarthWise Leave a Comment

Last year, Consumer Reports published a story stating that a third of chocolate products contain potentially dangerous amounts of heavy metals, in particular lead and cadmium. Since it contains much more cacao, dark chocolate was singled out as the most worrisome product. Needless to say, chocolate lovers found this report quite alarming.

A new study by Tulane University published in Food Research International employed a larger sample size, expanded the scope of testing to 16 metals, and included a risk assessment of toxic metals as well as accounted for the nutritional contribution of essential minerals.

The conclusions of the study were that dark chocolate poses no adverse risk for adults and contains nutritionally beneficial levels of essential minerals. Some risks remain for very young children, but only from a very small number of chocolate products and only when large quantities are consumed.

The study sampled 155 dark and milk chocolates from various global brands sold in the United States. It modeled the risk of eating one ounce of the chocolate per day or two large whole bars a week.

Only one brand exceeded the international limit for cadmium; four had cadmium levels that could pose a risk for a child weighing less than 33 pounds. Only two bars contained lead levels above California interim standard, but neither posed adverse risks for anyone.

Lead in chocolate comes from post-harvest processing; cadmium comes from the soil. South American chocolates generally have higher levels of metals than chocolates from Asia and West Africa. Most dark chocolate in the U.S. is sourced from West Africa.

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A dark side to dark chocolate? New study finds very minimal risk for kids from metals in chocolates

Photo, posted February 19, 2012, courtesy of Bodo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pollution From Tires | Earth Wise

October 16, 2023 By EarthWise Leave a Comment

A few years ago, researchers investigating massive deaths of coho salmon in West Coast streams discovered that the water contained particles from vehicle tires. The cause of the fish mortality turned out to be a chemical called 6PPD that is added to tires to prevent cracking and degradation. The mystery was solved, but so far, the chemical continues to be used by all major tire manufacturers and is found on roads and in waterways around the world.

Worse still, the acute toxicity of 6PPD and the chemicals that it transforms into when exposed to ground-level ozone is only the tip of the tire pollution iceberg. Tire rubber contains more than 400 chemicals and compounds, many of which are carcinogenic.

About 2 billion tires are sold across the globe each year and that number is expected to reach 3.4 billion by 2030. Tires are made from about 20% natural rubber and 24% synthetic rubber, which requires about 4 gallons of petroleum per tire. Hundreds of other ingredients – including steel, fillers, heavy metals like copper, cadmium, lead, and zinc – make up the rest.

Tire wear particles are emitted continually as vehicles travel. They range in size from visible pieces of rubber or plastic to microparticles. Research has shown that a car’s four tires collectively emit half a trillion ultrafine particles per mile driven. These particles are small enough to be breathed into the lungs and can travel throughout the body and even cross the blood-brain barrier. Particle pollution from tires exceeds that from tailpipes.

Tire pollution is a huge problem that is just starting to receive the attention it deserves.

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Road Hazard: Evidence Mounts on Toxic Pollution from Tires

Photo, posted June 22, 2018, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Metals In Western Water Supplies | Earth Wise

October 29, 2021 By EarthWise Leave a Comment

A new study published by the University of Colorado Boulder looked at the problem of rivers being contaminated by acid rock drainage. Rocks that include sulfide-based minerals, such as pyrite, oxidize when exposed to air and water. The resulting chemical reaction produces sulfuric acid which, when present in water, dissolves metals like lead, cadmium, and zinc. The recent study found that rare earth elements are also leached out of rock by this process.

Rock drainage occurs naturally throughout the western United States, but historic mines that disturbed large amounts of rocks and soil have dramatically increased this process and have led to growing downstream water pollution. Upwards of forty percent of the headwaters of major rivers in the West are contaminated by some form of acid mine or rock drainage.

The warming climate has brought longer summers and less snow in winters. Longer, lower stream flows make it easier for metals to leach into watersheds and concentrate the metals that would otherwise be diluted by snowmelt.

Rare earth elements are essential components of many high-tech devices such as computers, hard drives, and cell phones. There is not a long history of studying the hazards they might represent when they enter the environment.

The study looked at the Snake River watershed in Colorado and found that increasing amounts of rare earth elements are entering Colorado water supplies. Concentrations of rare earth elements are not ordinarily monitored and there are no water quality standards set for them.

According to the researchers, once rare earth elements get into water, they tend to stay there. Traditional treatment processes don’t remove them. It is a growing problem that needs to be addressed.

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Rare earth elements and old mines spell trouble for Western water supplies

Photo, posted October 27, 2007, courtesy of Dion Gillard via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Minerals And Metals For A Low-Carbon Future | Earth Wise

February 14, 2020 By EarthWise Leave a Comment

For the past century, economies and geopolitics have largely been driven by our insatiable appetite for oil and fossil fuels in general. As we gradually make the transition to a low-carbon energy future, the focus on oil will shift to sustainable supplies of essential minerals and elements.

The use of solar panels, batteries, electric vehicle motors, wind turbines, and fuel cells is growing rapidly around the world. These technologies make use of cobalt, copper, lithium, cadmium, and various rare earth elements. The need for any one of these things may diminish if alternatives are found, but there will continue to be a growing reliance on multiple substances whose physical and chemical properties are essential to the function of modern devices and technologies.

In some cases, global supplies of particular minerals and elements are dominated by a particular country, are facing social and environmental conflicts, or face other market issues. Shortages of any of them could create economic problems and derail progress much as the oil-related energy crises of the past have.

The world faces challenges in managing the demand for low-carbon technology minerals as well as limiting the environmental and public health damage that might be associated with their extraction and processing. Expanded use of recycling and reuse of rare minerals will be essential.

As the relatively easy sources of these materials become exhausted, other resources will become more attractive. These include various valuable ecosystems, oceanic deposits, and even space-based reserves.

Ushering in the low-carbon future is not a simple matter and will require responsible actions by the world’s governments and industries. In undoing the damage from the oil age, we must avoid new damage from the low-carbon age.

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Sustainable supply of minerals and metals key to a low-carbon energy future

Photo, posted March 13, 2015, courtesy of Joyce Cory via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.