Daniel Oberhaus | Motherboard | Source URL
Black plastics are notoriously hard to recycle, which has led to the introduction of toxic chemicals into consumer products using recycled black plastics.
Each year the world generates about 50 tons of e-waste—electronic items that are trashed because they are no longer useful or considered outdated—but only about 13 percent of this e-waste is recycled. This is a huge problem in itself, since most of this e-waste ends up in landfills in developing countries where the toxic chemicals found in the waste leach into local water supplies and poison the environment.
According to new research published in Environment International, however, even recycled e-waste poses a significant health risk because it contains toxic materials and is often used to make black plastics that come in contact with food.
“There are environmental and health impacts arising from the production and use of plastics in general, but black plastics pose greater risks and hazards,” Andrew Turner, a researcher at the University of Plymouth said in a statement.
Black plastics are colored using carbon black, a type of industrial pigment that is a desired additive in plastics for its durability and color. Its versatility means that it can be found in everything from garbage bags and DVD cases to coffee cup lids, plastic utensils, and takeout containers—in fact, black plastics account for about 15 percent of plastic waste in the UK, which has some of the best data on the stuff.
According to Turner, the problem is that carbon black is incredibly difficult to recycle using current plastic sorting techniques.
There are a variety of different types of plastics that are more or less difficult to recycle based on the complexity of the plastic’s molecular structure, which requires plastics to be sorted by type. Most sorting techniques used by recycling centers involve optical sensors that are able to determine what kind of plastic a recycled object is made from based on how the light reflects off the object back to the sensor. Black plastics, however, don’t reflect the light very well. This means black plastics usually just get sorted as regular waste and end up in a landfill, rather than recycled.
Since black plastics can’t be recycled, the demand for black plastic has to be met with other sources, such as e-waste. The majority of consumer electronic appliances that aren’t refrigerators or washing machines are black, so recycling these items seems like a good way to source black plastic. However plastics used in electronic appliances often have additives that are used to further insulate or fortify the electronics’ casing and are toxic to human health. These include antimony (durable when exposed to heat, but similar to arsenic in terms of its toxicology), bromine (used as flame retardants), and limited amounts of heavy metals such as cadmium, mercury, and lead.
Due to the presence of these hazardous substances in e-waste, recycling electronics is more heavily regulated than the recycling of other plastics. Yet as the researchers note in their new paper, a loophole in the Basel Convention, a widely adopted international treatise on the disposal of hazardous waste, allows companies exporting electronics to designate them as “repairable or to be ‘reused’ rather than as hazardous waste.” This means that e-waste can slip through the cracks and be recycled in ways that allow these chemicals to end up in black plastics used for food packaging and related products.
To find out how common these toxic elements found in e-waste are in black plastics, the University of Plymouth team used X-ray fluorescence spectroscopy—a type of chemical analysis that measures the level of secondary X-rays emitted by a material being hit with high powered X-rays—to determine the levels of lead, antimony, and other toxins are in over 600 products that use black plastic. These products were categorically arranged according to use (food-contact, clothing, toys, etc.). The researchers detected bromine in nearly half of the black plastics, while lead and antimony were found in about a quarter of the black plastics. According to the researchers, lead was “most commonly detected in the clothing and toys categories and least frequently in the food-contact category.
The presence of these potentially harmful chemicals in consumer items, including those that come in contact with food points to the problems of having a largely unregulated e-waste recycling global economy. Plastic recovered from electronics should be free from these hazardous materials, but inefficient recycling practices has “resulted in such a wide and uncontrolled dispersion of contaminants in black plastics that their eradication is now only possible through the manufacture of black goods from virgin materials,” the researchers wrote. Developing the technology to effectively recycle black plastics and reforming the e-waste recycling stream are large long term goals, but in the meantime the researchers advocate only recycling black plastics into products that have minimal contact with humans, such as road signs or garbage bins.
“Black plastic may be aesthetically pleasing, but this study confirms that the recycling of plastic from electronic waste is introducing harmful chemicals into consumer products,” Turner said. “There is a need for increased innovation within the recycling industry to ensure harmful substances are eliminated from recycled waste and to increase the recycling of black plastic consumer products.”