Migration of substances in plastics

Plastic is used everywhere: in packaging, kitchenware, toys, sports equipment, cars and electronic equipment to mention just a few.

In addition to polymers, plastic can include various substances either as impurities or as intentionally added substances. These substances may migrate to the adjacent environment called the recipient. Examples of recipients are air, water, food, blood, sweat and saliva.

When the substances can be hazardous to human health or the environment, the migration risk should be assessed.

We can help you with that!

We have developed a validated migration model to calculate the extent to which specific substances will be able to migrate to and from polymer materials and into a recipient.

With this tool we can assess the most important parameters, such as the diffusion coefficient and the partition coefficient, for various combinations of substances, polymers and recipients.

Among others, we can calculate:

• migration from plastic to recipients such as air, food and water
• migration to or through plastic, for example from printing inks on packaging
• the polymer’s absorption from the environment

Two factors in particular impact migration:

• The substance diffusion coefficient in the plastic matrix. This depends on different factors such as temperature and the so-called free volume, which is the space not filled by polymers and other substances.
• The substance partition coefficient between recipient and polymer. The partition coefficient is a measure of how well the substance is included in the recipient relative to the polymer matrix.

With a risk assessment of substances in the plastic, we can document the possible impact of the substances on human health or the environment. This is relevant in many contexts, including:

• REACH registration of a substance for use in an article if the substance is classified and the registrant has an annual tonnage above 10 tonnes/year.
• Pre-assessments, for instance if an additive used in food packaging constitutes a risk to human health.
• Other assessments, for example whether toy dyes pose a risk.