LCDs

USask scientists find potential toxicity of LCDs

Monday, January 6, 2020

A team of toxicologists at the University of Saskatchewan have discovered that chemicals used in smartphone, television and computer displays are potentially toxic and were found in several samples of household dust.

The international research team, led by USask environmental toxicologist John Giesy, is raising awareness about liquid crystal monomers—the chemical building blocks of everything from flat screen TVs to solar panels—and the potential threat they pose to humans and the environment.

“These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning,” said Giesy, Canada Research Chair in Environmental Toxicology at USask. “Now we also know that these chemicals are being released by products just by using them. We don’t know yet whether this a problem, but we do know that people are being exposed, and these chemicals have the potential to cause adverse effects.”

Published in Proceedings of the National Academy of Sciences on December 9, 2019. Giesy’s research team assembled and analyzed a comprehensive list of 362 commonly used liquid crystal monomers gathered from 10 different industries and examined each chemical for its potential toxicity.

The team also further tested the toxicity of monomers commonly found in six frequently used smartphone models.

The researchers found the specific monomers isolated from the smartphones were potentially hazardous to animals and the environment. In lab testing, the chemicals were found to have properties known to inhibit animals’ ability to digest nutrients and to disrupt the proper functioning of the gallbladder and thyroid—similar to dioxins and flame retardants which are known to cause toxic effects in humans and wildlife.

To understand how common these monomers are in the environment, researchers tested dust gathered from seven different buildings in China—a canteen, student dormitory, teaching building, hotel, personal residence, lab, and electronics repair facility. Nearly half of the 53 samples tested positive for the liquid crystal monomers.

“Ours is the first paper to list all of the liquid crystal monomers in use and assess their potential to be released and cause toxic effects,” said Giesy. “We looked at over 300 different chemicals and found that nearly 100 have significant potential to cause toxicity.”

Ninety per cent of the monomers tested had concerning chemical properties. They either accumulate in organisms, resist degradation in the environment, or are easily transported long distances in the atmosphere. Nearly one quarter of the chemicals tested had all three troubling characteristics.

“There are currently no standards for quantifying these chemicals, and no regulatory standards,” said Giesy. “We are at ground zero.”

LCD panels are almost exclusively produced in three Asian countries: China, Japan, and South Korea. It’s estimated that 198 million square metres of liquid crystal display were produced last year—enough to cover the entire Caribbean island of Aruba. For many years, huge amounts of globally produced e-waste—including LCD displays—have been dismantled, disposed of, and introduced into the environment.

“Right now, there are no measurements of these monomers in surface waters. Our next steps are to understand the fate and effect of these chemicals in the environment,” added Giesy.

 

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