2 research outputs found
Size-Controlled Preparation of Polyethylene Nanoplastic Particles by Nanoprecipitation and Insights into the Underlying Mechanisms
Plastic pollution is ubiquitous in the environment, and
nanoplastics
(<1 ÎĽm) are of growing concern as they pose more health risks
than larger particles. However, because of a lack of appropriate model
particles, studies examining the risks of polyolefin nanoplastics
are very limited, despite the prevalence of these plastics in the
environment. Although nanoprecipitation using organic solvents is
a promising method for preparing model nanoplastic particles of polyolefins,
there are currently no methods for controlling the particle size.
Here, we examined how the concentration and volume of the feedstock
polymer solution affect the size of polyethylene particles produced
by nanoprecipitation. The mechanisms underlying the particle formation
were investigated by using a simple population balance model. Increasing
the concentration of the feedstock solution increased the growth rate
and decreased the nucleation rate, and increasing the volume of the
feedstock solution increased the growth rate, resulting in an increase
in the mean particle diameter in both cases. These changes in particle
diameter were linearly correlated with the suspension density of the
dispersion up to a suspension density of 0.4 mg·mL–1. In addition, at these suspension densities, spherical particles
were prepared without generating aggregates. Together, these results
show that the diameter of polyethylene particles prepared by nanoprecipitation
could be controlled according to the suspension density up to a suspension
density of 0.4 mg·mL–1. This study provides
a basis for the development of nanoprecipitation-based techniques
for the precise, scale-independent production of model nanoplastic
particles, which we hope will accelerate the risk assessment of nanoplastics
Facilitated Leaching of Additive-Derived PBDEs from Plastic by Seabirds’ Stomach Oil and Accumulation in Tissues
Our
previous study suggested the transfer of polybrominated diphenyl
ether (PBDE) flame retardants from ingested plastics to seabirds’
tissues. To understand how the PBDEs are transferred, we studied leaching
from plastics into digestive fluids. We hypothesized that stomach
oil, which is present in the digestive tract of birds in the order
Procellariiformes, acts as an organic solvent, facilitating the leaching
of hydrophobic chemicals. Pieces of plastic compounded with deca-BDE
were soaked in several leaching solutions. Trace amounts were leached
into distilled water, seawater, and acidic pepsin solution. In contrast,
over 20 times as much material was leached into stomach oil, and over
50 times as much into fish oil (a major component of stomach oil).
Analysis of abdominal adipose, liver tissue, and ingested plastics
from 18 wild seabirds collected from the North Pacific Ocean showed
the occurrence of deca-BDE or hexa-BDEs in both the tissues and the
ingested plastics in three of the birds, suggesting transfer from
the plastic to the tissues. In birds with BDE209 in their tissues,
the dominance of BDE207 over other nona-BDE isomers suggested biological
debromination at the meta position. Model calculation of PBDE exposure
to birds based on the results of the leaching experiments combined
with field observations suggested the dominance of plastic-mediated
internal exposure to BDE209 over exposure via prey