Acute immunotoxicological effects of traffic-related micro- and nanoplastics in urban air.

There is increasing concern about micro- and nanoplastics (MNPs) in the
environment. One of the predominant sources releasing MNPs into the atmosphere
is motorized road traffic tyre wear. No research has thus far studied uptake in
the blood stream and potential health effects of airborne MNPs. This research
will therefore investigate the concentrations of MNPs people are exposed to,
and which short term health effects may occur in urban settings.

The main objective is to study presence of MNPs in blood and short-term changes
in blood leukocytes, inflammatory markers and the anti-oxidant defence system,
in association with traffic-related microplastic exposure in healthy young
adults. Secondary outcomes are changes in respiratory function and inflammatory
markers in saliva.

The study has a controlled repeated measures design, assessing the presence of
MNPs in blood and short-term immuno-toxicological health effects in healthy
people aged 18 - 45 years exposed at three locations in Utrecht at the same
time-of-day: highway, stop-and-go traffic location and an urban parc. Exposure
will take 4 hours and include intermittent exercise. The highway and the
stop-and-go location probably have a high contrast in MNPs. During these
sessions, MNPs will be collected on filters for physicochemical analysis, and
the presence of other traffic-related major air pollutants (black carbon (BC),
ultrafine particles (UFP)) will be continuously monitored. Blood and saliva
will be collected before, immediately after and 17 hours after each session.
Furthermore, before and immediately after each session, we will perform lung
function measurements and ask the volunteers to fill in a questionnaire
regarding respiratory symptoms.

The volunteers will be asked to participate in 3 separate sessions of each 7
hours, over the course of 5 months, amounting to about 21 hours in total. In
two sessions, exposure to MNPs, predominantly from abrasion of tyres from
vehicles will occur, in varying concentrations. The third session, which will
take place in an urban parc with low concentrations of MNPs from tyres, will
have an identical set-up to the other sessions. All tests will be performed by
trained project-employees and experts for the collection of blood. We are not
sure what the health risks are of exposure to traffic-related MNPs, since this
is the topic of this study. However, we do not expect additional risks compared
with the normal situation. For example, food delivery cyclists are exposed to
similar concentrations for similar or even longer durations, also while cycling.
Participants will not personally benefit from the scientific outcomes of the
study. It is expected that the people are interested to participate in the
study, due to the emerging global environmental awareness and health concerns
of plastic pollution. As an appreciation for their participation, the
participants will receive a gift certificate of 175 euros, once they complete
the three sessions.