Regulatory Definition of Microplastics and Oxo-degradable Plastics

Little Pro on 2018-12-05

Microplastics are tiny pieces of plastics with diameters less than 5mm.  It is not the same thing as 'Microbead". Microbead is just a microplastic used in a mixture as an abrasive i.e. to exfoliate, polish or clean.Those microplastics degrade very slowly in the environment and can go down the drain and enter our lakes, rivers, and oceans, posing a big threat to aquatic organisms.  Microplastics can be used in cosmetics, fertilizers, plant protection products, cleaning and maintenance products. 

Definition of Microplastics

The common definition of microplastics is that they: 

  • are synthetic materials with a high polymer content,
  • solid articles, 
  • smaller than 5 mm,
  • insoluble in water, and
  • not degradable.  

Microplastics are mainly synthetic polymers. However, polymers will only be called microplastics if they meet all criteria above. Polymers are widely added to cosmetic formulations or pesticide formulations as disperants or surfactants. Some polymers are soluble in water while the others are not. The degradability of a polymer shall also be taken into account. 

In Jan 2019, ECHA published its draft REACH restriction report for microplastics. In the report, microplastics is defined as a material consisting of solid polymercontaining particles, to which additives or other substances may have been added, and where ≥ 1% w/w of particles have (i) all dimensions 1nm ≤ x ≤ 5mm, or (ii), for fibres, a length of 3nm ≤ x ≤ 15mm and length to diameter ratio of >3.


Soluble and Insoluble Polymers

Microplastics are polymers with low water solubility. Because microplastics are poorly soluble in water and do not degrade, they may persist in aquatic environment, absorb toxins in the water, be eaten by marine life and eventually enter our food chain.

Insoluble Water soluble
  • polystyrene (PS)
  • polyethylene (PE)
  • polypropylene (PPE)
  • polymethyl methacrylate (PMMA)
  • polyvinyl chloride (PVC)
  • polyisobutilene (PIB)
  • polyethyleneglycol (PEG)
  • polyacrylic acid (PAA)
  • polyacrylamide (PAM)
  • polyvinyl alcohol (PVA)

Sources of Microplastics

Microplastics come from a variety of sources, including from larger plastic debris that degrades into smaller and smaller pieces. The most well-known source is microbeads, which are very tiny pieces of manufactured polyethylene plastics used as exfoliants in some cleansers and toothpastes.

In addition, intentionally-added microplastic particles can be found in a range of products such as personal care products, detergents, cleaning products, paints and plant protection products.

Oxo-degradable Plastics

EU is also looking at the ban of oxo-degradable plastics. Oxo-degradable plastics are conventional plastics that contain additives that promote the oxidation of the material under certain conditions. They are used in applications such as agricultural films, rubbish and carrier bags, food packaging, and landfill covers. They can break down into very small particles, potentially contributing to environmental contamination by microplastics.

More Readings

Global Ban on Microbeads in Personal Care Products


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