Joint Sask. University/China study reveals IAQ risk from LCD screens

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Prof. John Giesy checks a sample in his lab.

Chemicals used in the liquid crystal display (LCD) screens of smartphones, televisions and computers have been found in nearly half of all samples of household dust collected by a team of toxicologists led by the University of Saskatchewan. The particles are believed to be potentially toxic.

Liquid crystal monomers – the chemical building blocks of everything from flat-screen TVs to solar panels – can pose a potential threat to humans and the environment. The study is being headed up by the University of Saskatchewan environmental toxicologist John Giesy. The paper was published on Dec. 2 in Proceedings of the National Academy of Sciences.

“These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning. Now we also know that these chemicals are being released by-products just by using them,” said Giesy, research chair in environmental toxicology. “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.”

His research team has assembled and analyzed a list of 362 liquid crystal monomers gathered from 10 different industries and examined each chemical for its potential toxicity. The research found that specific monomers from smartphones were potentially hazardous to animals and the environment. In lab testing, the chemicals were found to have properties known to inhabit the animals’ ability to digest nutrients and disrupt the proper functioning of the gallbladder and thyroid.

China/Canada partnership

In China, seven buildings were tested to determine how common the monomers are in the environment. A canteen, student dormitory, teaching building, hotel personal residence, lab, and electronics repair facility were tested as part of the study.

Nearly half of the 52 samples tested positive for the liquid crystal monomers. Ninety per cent tested positive for 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 positive for all three characteristics.

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

Guanyong Su of China’s Nanjing University of Science and Technology is leading the Chinese team. He was a former student with Giesy at the University of Saskatchewan and then a post-doctoral fellow with Environment Canada. Doug Crump and Robert Letcher represent Environment and Climate Change Canada in the study.

Growing risk

It is estimated that 198 million sq. metres of liquid crystal display were produced last year – enough to cover the entire Caribbean island of Aruba.

“Since there are more and more of these devices being made, there’s a higher chance of them getting into the environment,” said Giesy. “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.”

The research was supported by the National Natural Science Foundation of China, other Chinese research funding programs, and Environment and Climate Change Canada.

In his previous work, Giesy was also the first researcher to identify that toxic perfluorinated and polyfluorinated chemicals were widespread in contaminating the environment. His research resulted in the entire class of chemicals being banned globally.

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