New carcinogens discovered in rubber granulates

It has recently been discovered that the rubber granulates in artificial turf contain even more harmful and carcinogenic substances than had previously been assumed. Furthermore, several of these substances are even more prone to leaking than the substances in rubber granulate that had already been identified as being harmful. This information was revealed by a new doctoral study conducted by chemist Ewa Skoczynska from Vrije Universiteit Amsterdam (VU). According to her supervisor, Jacob de Boer, a professor of environmental chemistry and toxicology, these findings mean that the current standards for rubber granulate should be much stricter.

A total of 46 substances have been found, about half of them are new substances, several of which are carcinogenic or otherwise harmful.

In addition to the group of known carcinogens, Skoczynska also discovered a group of suspected carcinogens. There is also a third group of substances, but nothing is known of their toxicity and more research is needed to establish their effects under specific circumstances.

Up until now, research into the health and environmental risks posed by artificial turf has focused exclusively on the 16 polycyclic aromatic hydrocarbons (PAHs) that are already known to be carcinogenic and harmful. The current safety standards for artificial turf are based on this knowledge.

According to Professor De Boer and Ms Skoczynska, the standards currently approved by the National Institute for Public Health and the Environment (RIVM) are in need of an overhaul because an increased number of toxic substances that are also more prone to leaking from rubber granulates not only increase the risks to the environment, but also the risks to health, especially if they come into contact with skin, which occurs when people play sports on artificial turf. “There are therefore much stronger indications of greater risks. Rubber granulates contain many more substances”, said Skoczynska.

According to Skoczynska, what is different about the properties of a number of the newly-discovered substances is that, unlike the carcinogens that are already known, these substances leak out of rubber granulates more easily. “This is definitely a problem for the environment.”

The cumulative effect of all these substances together is not yet clear. “We still have a lot to learn in this respect”, said Professor De Boer. According to the professor there is a real likelihood that these substances reinforce each other.

Shortly after ‘Dangerous Play’ − Zembla’s first programme on the health risks of exercising on artificial turf containing rubber granulate, broadcast in 2016 − VU University conducted a study involving zebra fish. When the fish and their embryos were exposed to water containing rubber granulates, the embryos died and the fish displayed behavioural changes.

VU University found that this study indicated that rubber granulate contains more than just PAHs and the 16 substances that are already known to be harmful and it is necessary to identify them. Until we know more some scientists, including toxicologist Martin van de Berg, said that the government should apply the precautionary principle and prohibit sporting activities on artificial turf. The RIVM, however, maintained that it is safe to play on artificial turf.

The VU continued its research into rubber granulates. Skoczynska used a new method to identify unknown substances in rubber granulate. Using an ultrasonic treatment method enabled her to extract more substances from granulate, which she then screened using an advanced new technique that had not previously been used to measure substances in rubber granulate.

This new technique enabled Skoczynska to identify 46 substances. If this research is continued, she is convinced that she will find even more substances in rubber granulate.
This doctoral research has come at an extraordinary moment. The European Commission is currently reconsidering the future of artificial turf pitches containing rubber granulate in Europe in its efforts to combat environmental pollution caused by microplastics.

The granules in rubber granulate are classified as microplastics. De Boer finds that the newly discovered toxic substances are crucial to determining the new standards to be set by the European Chemicals Agency (ECHA).

The current standard for rubber granulates is 2000 times less strict than the standard for toys. But because many children play sports on artificial turf containing rubber granules, numerous scientists have been calling for stricter standards for some time. “We now find that PAHs are not the only reason why the standard should become more stringent. Rubber granulate contains many more harmful substances, which is an extra reason for a drastic reduction”, said De Boer.

The professor expects that sports fields containing rubber granulate will eventually become a thing of the past. “I am pretty sure of this. You do not want to run this kind of risk and these types of sports fields are not even necessary.”

Watch 'Dangerous Play' (2016) and 'Dangerous Play - the sequel' (2017):