Chemistry: Risks from atmospheric products of commercial chemicals assessed

The products of reactions in the atmosphere between commercial chemicals may be more toxic than the original parent chemicals, suggests a paper published in Nature. The study indicates that these chemical products are found in the atmospheres of 18 megacities and might present a previously unrecognized exposure risk for the populations.

Commercial chemicals are used across urban centres and pose a potential risk to around 4.2 billion people. Harmful chemicals are assessed on their persistence within the environment, potential for bioaccumulation (the accumulation of chemicals in an organism), and toxic properties, and their use is governed by national and international frameworks. However, regulations are often decided on the basis of our knowledge of the parent chemicals, and little is known about the potential effects of the products of their interactions in the atmosphere.

John Liggio and colleagues used a combination of laboratory and field experiments, suspect chemical monitoring and modelling to develop a framework for assessing the risk of airborne chemicals, accounting for their reactions in the atmosphere. They then applied this framework to organophosphate flame retardants, which are widely used in consumer and industrial products. The authors found that on average the transformational products can be more toxic and an order of magnitude more persistent than the original parent chemicals. They also suggest that the overall risk can be greater from the transformational product than that from the parent chemical.

The authors found that transformational chemicals were distributed across 18 global urban centres, including London and New York, posing a potential risk for urban populations. This research highlights the need to consider atmospheric transformations when assessing the potential risk posed by commercial chemicals, the authors conclude.