Toxic Decomposition Products – City air contains components of flame retardants

December 2019: Smog over the Chinese capital Beijing (dpa / Qing Chun)

The air of big cities is apparently teeming with unknown breakdown products of common industrial chemicals. This is demonstrated by the new Canadian study using the example of organophosphates. This group of substances is used worldwide as a flame retardant, for example in furniture, household and electronic equipment. The substances are not firmly bound in it, however, and some of them escape. Reactions in the atmosphere turn the organophosphates into a number of other, previously undiscovered chemicals, as the researchers are now showing with their publication in the specialist journal “Nature”. John Liggio of the Canadian State Environmental Protection Agency in Toronto is one of the study directors:

“We selected nine organophosphates and first of all simulated in the laboratory what would arise from them under conditions such as in city air. That was almost 200 different breakdown products! We characterized them chemically and physically and then checked whether we could find them outside in the real atmosphere. “

Air samples from New York, Tokyo and Istanbul

The researchers had air samples from 18 megacities around the world, including New York, Tokyo, Beijing, Sydney and Istanbul. London, Warsaw and Madrid were also represented, but German cities were not. In fact, the analysts found 19 breakdown products of the organophosphates in the samples. Ten of them are found in every megacity:

“But these are only minimum numbers! Our devices for analyzing air samples only record certain chemical breakdown products and not all that one might expect. “

Chemicals of emerging concern

Organophosphates are compounds derived from phosphoric acid. In many cases, how toxic they are has not yet been adequately investigated. But they are considered chemicals of emerging concernas chemicals are the growing cause for concern, as John Liggio says. We know of various technical organophosphates that they impair the effect of body enzymes and can damage the nervous system. But what about the newly discovered degradation products in the city air?

“We can estimate the risk of the breakdown products compared to the parent substance, and we have done that. With some organophosphates, 80 percent of the breakdown products are more toxic than the original substance. And if they contain chlorine, then the derivatives are also more persistent, so they remain in the environment longer. ”

Health hazard still unclear

But the chemist cannot say whether the health of people in megacities is at risk if they inhale the converted flame retardant active ingredients:

“Nobody collapses on the street because of this, I can assure you! However, long-term effects are possible. We cannot yet say whether they exist. ”

“You should also include the breakdown products of the substance”

The concentrations of the chemicals were highest in New York and London. The peak value was 15 nanograms per cubic meter of air. That is not a lot. But pollutants are almost always only present in trace concentrations in the environment, according to Liggio. The chemist hopes his study will send a signal for the approval of new substances:

“Let’s say the industry comes tomorrow with a new chemical that it wants to use. Then it is not enough just to evaluate them. The breakdown products of the substance should also be taken into account. Any industrial chemical released into the atmosphere will likely form dozens or hundreds of other compounds. “

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