In response to a request from the Scientific Advisory Board, RIVM conducted an international review of the rubber granulate study. The scientific sounding board group that was consulted on the study on the “Evaluation of health risks of playing sports on synthetic turf pitches with rubber granulate” consisted exclusively of national experts from the Netherlands. The Scientific Advisory Board therefore asked RIVM to arrange for an international review of the research report.

To that end, RIVM contacted reviewers from three prominent institutes who are experienced in risk assessment within regulatory frameworks. Reviewers from the United States Environmental Protection Agency (US-EPA) (on personal title), the German Bundesinstitut für Risikobewertung (BfR) and the European Chemicals Agency (ECHA) assessed the report and provided their findings. RIVM is very appreciative of the expert response.

The conclusions from these reviews largely echo the debate on rubber granulate in society and are an important reflection on the work done by RIVM. These reviews assist us in ongoing discussions with our fellow risk assessors and the Ministries that commission our work. The original summaries of the reviews have been posted on the RIVM website (in the right column of this page).

Primary conclusions from the reviews and response from RIVM
The reviewers were unanimous in stating that the quality of the RIVM study was very good. There was great appreciation for how the study was conducted, certainly considering the time constraints on the study. The reviewers did add a number of comments, some of which had already been addressed in various chapters of the RIVM report.

  • One of the significant comments is that the description of the analytical and chemical aspects was limited. We endorse this finding. RIVM outsourced the majority of the analytical procedures to external, certified laboratories. These laboratories conducted their tests according to ISO and NEN standards. These national and international standards specify how the analyses are performed. The laboratories that conducted the tests have the full details.
  • Another comment provided by the reviewers is that the RIVM researchers made assumptions in order to facilitate choices during the research process. The question posed by the Minister of Health, Welfare and Sport and the time frame in which her question had to be answered led RIVM to opt for an evaluation of the actual (current) situation, rather than a preventive/regulatory risk assessment that is carried out for example in the case of product authorisation. An evaluation of the risk in an actual situation is conducted at the time of exposure, in order to determine whether the exposure level is within acceptable limits. In a preventive/regulatory risk assessment, safe levels are derived and all substances are considered in great detail. RIVM opted for a prioritisation strategy in combination with the assumption of a worst-case scenario for exposure. In other words, we used the highest measured concentrations and an extreme level of contact. Moreover, we focused on the substances that are of very high concern (i.e. substances that may pose serious health risks). The aim of the research was to answer the question whether playing sports on synthetic turf pitches with rubber granulate poses health risks.
  • The reviewer from ECHA endorses the RIVM response to the question of whether playing sports on rubber granulate poses a health risk in this actual situation. The reviewer from EPA finds the RIVM response adequate for the given conditions, as evaluated. The reviewers from BfR note that in the light of several uncertainties, many of which are due to the extremely short time available for answering the question asked by the Minister of Health, Welfare and Sport, further research would be needed in order to gain more certainty. However, considering the task of assessing the risks from rubber turf pitches as a basis for decisions on immediately required actions, the German reviewers confirm that the RIVM research results are substantial enough and can be accepted as a preliminary, indicative assessment.

It is clear that there are different views on the desirability of playing sports on rubber granulate, not only in the social but also in the scientific field. The RIVM report on rubber granulate can be used by parties in society for making an assessment whether or not to use rubber granulate. A consideration in which besides the health aspects also environmental aspects, costs, the perception of risks of citizens and social acceptance play a role. These are not covered in the report and it is up to the competent authorities to weigh/assess these aspects. Naturally, there are many aspects that can be further investigated, also in an international context. RIVM has already indicated that 'the book on rubber granulate' cannot be closed. We follow the discussions and new studies on the effects of rubber granules on health. We have carried out a risk assessment of the current situation and concluded that playing sports on rubber granulate is safe, as far as the effects of rubber granulate on health are concerned. The effect of these substances on human health is virtually negligible. In addition to the results on the health effects, two topics emerged that RIVM continued to implement in 2017 and 2018. In the 2016 study, the environmental risks of rubber granulate were not taken into account, but RIVM did (again) point to these environmental risks. Moreover, there were many questions from society about the environmental aspects of synthetic turf fields with rubber infill. For this reason, RIVM submitted a research proposal to the Ministry of Infrastructure and Public Works in mid-2017. This led to the commission for an exploratory environmental study in which RIVM maps to what extent rubber granulate as infill affects the environment. The results of this research are expected to be public by mid-2018. Secondly, it emerged that the limit value for PAHs in rubber granulate is high. If the concentration of PAHs is actually as high as the standard allows, then a safe level cannot be guaranteed. That is why RIVM, together with ECHA, has started a process to establish a new limit value.

In addition, RIVM has repeated a number of the experiments originally conducted in the study, particularly the experiments on migration into gastrointestinal fluids. These data results were in line with the experiments conducted previously. Additional analytical research has been carried out to see if we have overlooked important substances in the risk assessment. This appeared to not be the case. The supplementary data will be published on the website.