A new study has found that glitter can negatively affect the growth of cyanobacteria, commonly called ‘blue-green algae,' an important player in aquatic ecosystems and a key component of marine food webs. The researchers say their study highlights the importance of reining in the use of this stealthy microplastic.
Despite its association with fun things – makeup and nail polish, party costumes, greeting cards and holiday decorations – glitter is a problem. Not only is it seemingly impossible to remove once it has stuck to clothing and skin, but its microplastic composition also poses an environmental threat, especially to oceans and waterways.
Typically made of tiny particles of polyethylene terephthalate (PET) or polyvinyl chloride (PVC) coated in aluminum to create a reflective surface, this “plastic in disguise” joins the estimated 8.8 million tons (8 million metric tonnes) of microplastics that make their way into our oceans as they're too small to be filtered out by wastewater treatment plants.
Researchers affiliated with the University of São Paolo studied the effects of glitter on the growth patterns of cyanobacteria, a key player in aquatic ecosystems.
Cyanobacteria, an aquatic bacterial relative that obtains energy via photosynthesis, play a vital role as primary sources of oxygen and fix nitrogen levels in aquatic environments. As a type of phytoplankton, cyanobacteria are also a key component of marine food webs, although they’re prone to forming harmful algal blooms that can disrupt aquatic ecosystems and are toxic to humans and animals.
The researchers examined the effects of different concentrations of glitter particles on two bloom-forming strains of cyanobacteria, Microcystis aeruginosa and Nodularia spumigena.
The cyanobacterial strains were cultivated in a medium for 21 days under five concentrations of glitter: zero, 50, 100, 200, and 350 mg of glitter per liter (mg/L) of water. The researchers measured the strains’ cellular growth rates every three days, using spectrophotometry to measure the intensity of light absorbed and transmitted by each sample.
For M. aeruginosa, a growth peak was recorded in the 50 mg/L glitter treatment, with the lowest growth recorded at a concentration of 200 mg/L. In the N. spumigena samples, glitter concentrations above 137.5 mg/L negatively affected cell density from which the cyanobacteria didn’t recover. The change in growth rates for N. spumigena was only seen on the last day of the experiment.
“We found that increasing the amount of glitter raised the biovolume of the cyanobacterial cells and boosted stress to levels that even impaired photosynthesis,” said Mauricio Junior Machado, the study’s lead author. “The toxicity of glitter for microorganisms has hardly been studied at all. Whatever affects cyanobacteria will indirectly affect other organisms in the same environment.”
With our increased knowledge about the environmental impact of microplastics, over the past few years there’s been a push to use eco-friendly glitter alternatives, such as colored rice, salt, sand, or paper. Researchers at Cambridge University even came up with a plant-based glitter that contains no plastic or aluminum.
The researchers hope their study will further educate people about the importance of avoiding microplastic pollution.
“Glitter is sold for use in festivities, where people spare little thought for the environmental problems it causes,” said Marli de Fátima Fiore, corresponding author of the study. “However, it’s necessary to bear in mind that microplastics contaminate and damage marine and freshwater ecosystems, which are extremely important to our lives, and to think about campaigns to avoid microplastic pollution as much as possible.”
The next step for the researchers is to perform the same experiments on other strains of cyanobacteria and to see whether biodegradable glitter poses a similar problem to the environment.
The study was published in the journal Aquatic Toxicology.
Source: Agência FAPESP
