1 | INTRODUCTION
Nanoparticles (NP) (usually understood as in the range 1-100nm) are, in
principle, capable of intercellular barrier penetration as well as
ingestion by cells, particularly phagocytes and transporting epithelia.
Here we focus on particulate black carbon (BC) and nanoplastics.
BC arises as a sooty paracrystalline insoluble product during combustion
of wood, other plant material (including tobacco combustion products
inhaled by smokers) or petroleum products in spaces with limited oxygen.
It is used as a stabiliser in tyre manufacture, paints and pigments and
as a food colourant. Particulate material from vehicle emissions is
classified by size, for example PM2.5 are
NP<2.5nm. Carbon NP are produced by design too, for example as
nanofibres or nanotubes. Routes of exposure are most likely to be via
inhalation or ingestion. High exposures may occur as a result of vehicle
emissions from nearby roads. Epidemiological studies have suggested
associations between particulate air pollution (including
PM2.5) and hypertensive disorders of pregnancy, growth
restriction and preterm birth but are often confounded by the presence
of other pollutants.
Microplastics (around 1-100mm) in the environment generally arise from
pellets, packaging, personal protective equipment, textiles, tyres or
fishing nets, either directly as a by-product of manufacturing or by
mechanical, light-mediated or biological fragmentation and degradation.
They are already very widespread in soil and aquatic environments, and
concentrations are rising. Microplastics break down into nanoplastic
particles which are more difficult to detect and quantify, and more
likely to become incorporated from air, water, soil or food into
biological systems. In addition, primary nanoplastics are directly made
for use in cosmetics, facial cleansing products, and air blasting
technologies. There are currently no data showing a direct association
between microplastics and abnormal pregnancy outcomes.
Research is required to inform the updating of legislation to protect
women as early as possible in their pregnancies, or ideally those
planning a pregnancy. Within this context, epidemiology data supported
by laboratory investigations are essential in understanding the
placental transfer of NP and their impact on placental biological
function and fetal development.