An investigation led by the Autonomous University of Madrid and the University of Alcalá de Henares has revealed the presence of microplastics in the drinking water of several Spanish cities, although in concentrations that pose an insignificant risk to human health.
Along with the plastics, traces of other man-made materials were also found, such as dyed cotton fibers from clothing, which are a potential source of additives such as dyes.
For the study, whose conclusions have been published by Water Rsearch via EviroPlaNet (a network that coordinates more than a dozen Spanish research groups on plastic pollution), samples were taken at 24 points in eight towns in Pontevedra, Coruña, Madrid, Barcelona, Murcia and the Canary Islands in May and July 2022.
The sampling was carried out in the metropolitan areas of Madrid and Barcelona, with 7.3 and 5.5 million inhabitants, respectively; and medium-sized populations, such as San Cristóbal de La Laguna (155,000 inhabitants) or Murcia (450,000), by placing steel filters in homes and public places.
Microplastics were found in all the samples, according to the study, which reveals an average concentration of plastics of 12.5 ± 4.9 microplastics per cubic meter of water, and 32.2 ± 12.5 particles per cubic meter of water in the case of artificial materials.
The most detected plastics were polyamides, polyesters and polyolefins, materials used for the manufacture of numerous objects of common use and in textile garments.
According to the same source, the careful characterization of all the particles in the study allowed estimates of the mass of microplastics contained in the processed samples: 45.5 nanograms per liter.
"This is a small value and is comparable to other contaminants that appear in surface water and from there reach the network water, such as antibiotics. Consuming 1.5 liters of water every day it would take 40 years to ingest 1 milligram , which most likely indicates that the risk to human health is negligible. This is good news," according to the authors.
However, "one does not expect plastic to come out of the tap", according to the researchers, who have highlighted that the study has shown that despite the fact that the mains water in the most populated area, Madrid, was the one that contained the most microplastics, " plastic debris appeared in all samples at a fairly similar concentration."
The most probable origin is in the diffuse contamination that reaches the channels from which the drinking water treatment stations take water and, in general, receive wastewater from treatment plants located upstream, according to the same source.
In his opinion, wastewater discharges, even if they are properly treated according to current parameters, are an important source of microplastics discharged into the environment.
This indicates that "the waste that we end up discarding in our homes ends up returning to them" and hence the importance "that we manage the waste that we generate correctly", according to the same source.
