Researchers found the most abundant microplastics were polyethylene, from for example degraded plastic packaging or carrier bags; and nylon, which may be from clothes; as well as resins, which could come from degraded roads, paint marking or tyre rubber. Researchers also found microplastics of the size and shape which are inhalable by humans.
The characteristics of microplastics were largely fragment and film shapes, which are unique to degraded plastics for example plastic bags or bottles, rather than fibres, which are more abundantly found indoors.
Lauren Jenner, lead author and postgraduate student at Hull York Medical School, said: “We found a far greater number of microplastic particles than we were expecting. This study underlines that microplastics are everywhere. It shows they are present in high levels in selected outdoor areas, and that the levels can be higher than indoors.
“It is vital we now investigate outdoor environments in which humans are regularly exposed to in order to find out the levels of exposure and the types of microplastics present. Inhalation of microplastics is an emerging cause for concern because we know from recent studies that they have been observed in human lung tissue samples. Plastics are designed to be durable, so they may remain inside the body for long periods without the possibility of these being broken down or removed. These findings can now form part of future work to help determine any health impacts, allowing us to now use representative types and realistic exposure levels of such microplastics in further cell studies.”
The study also took samples during the UK-wide lockdown in 2020, providing one of the first datasets for the time period around atmospheric microplastics. Despite a much lower level of traffic and only key-workers allowed to work, the levels of microplastics detected did not significantly change.
Lauren said: “Because microplastics are an emerging contaminant type, there are few studies available. These studies are important because we are producing datasets for the first time that will allow regulatory bodies, such as DEFRA, and clinicians complete more in-depth risk-based approaches to monitoring, and studies on the effects of microplastics in the future.”
The full article is published in the journal Atmosphere and can be found here.
In a recent statistical analysis of the available literature on the effects of microplastics using human cell studies, the levels of microplastics which may lead to harmful effects were highlighted.
The study compared the concentrations of microplastics that affected cell viability to the concentrations that we are exposed to by ingesting contaminated food and water using three previous studies by the Human Health and Emerging Environmental Contaminants research group at the University of Hull.
These studies focused on microplastic contamination of drinking water, seafood and table salt and revealed high levels of human exposure to microplastics from consuming these. This recent work offers another route of exposure for consideration of the potential exposure and impacts of microplastics in humans; that of inhalation.