A fundamental underpinning of the silicone industry’s commitment to product stewardship is the belief that comprehensive, robust, weight-of-evidence, risk-based assessments should be the primary driver for development of regulatory policy. A fundamental requirement for the development of scientific assessments is the availability of high-quality data. The silicone industry’s willingness to develop those data is also an illustration of the industry’s commitment to generation of sound science to support regulatory decision-making.
In early 2018, the Global Silicones Council (GSC) entered into a tri-party agreement with the China Association of Fluorine and Silicone Industry (CAFSI), and the Solid Waste and Chemical Management and Technology Center (SCC), to conduct an environmental risk evaluation on D4 in China. The intent of the evaluation is to address Chinese facilities that manufacture, process and/or use D4. The Evaluation will assess the risks to environmental organisms from exposure to D4 using appropriate and applicable models and input parameters to predict local emissions and the environmental receptor concentrations associated with Chinese facilities that manufacture, process and/or use D4. The Evaluation will include a hazard assessment, exposure assessment, risk characterization, and a risk determination for environmental exposure to D4 associated with Chinese facilities that manufacture, process and/or use D4.
The data and information resulting from this assessment should inform the need for prioritization of further assessment or any preventive risk management for D4.
The target timeframe for the completion of the risk evaluation is May 2020.
Australia’s Department of the Environment and Energy carried out a risk assessment for a range of silicone materials, which concluded in 2018. Australia’s assessment focused on a series of siloxanes, including D3, D4, D5, D6, D7, and cyclomethicone. Australia’s assessment for D4, D5, and D6 is consistent with Canada’s assessment for these three materials.
The assessment from Australia’s Department of the Environment and Energy concludes, “[t]he direct risks to aquatic life from exposure to these chemicals at expected surface water concentrations are not likely to be significant.” Based on this conclusion, Australia has not proposed regulatory restrictions on the use of any of the materials. Health assessments have also been completed with no significant identified human health risks.
In January 2009, Environment Canada identified D4, D5 and D6 as priorities for regulatory evaluation on the basis of hazard screening criteria. Further to a comprehensive screening assessment of these materials, Canada has not imposed any use restrictions or concentration-based restrictions on the use of D4, D5, or D6 for any product in Canada.
For D5, the Canadian Environment Minister established a first-ever Board of Review in which independent scientists identified by the Minister reviewed the available science to determine whether D5 could pose a risk to the environment. Following a scientific review process that included formal hearings and a rigorous examination of all the relevant scientific information related to D5’s behavior in the environment and any potential danger posed by the substance, the Board concluded in October 2011 that “siloxane D5 does not pose a danger to the environment or its biological diversity.” Furthermore, the Board concluded that, “based on the information presented, siloxane D5 will not pose a danger to the environment or its biological diversity in the future.”
In February 2012, the Canadian Environment Minister accepted the Board of Review’s findings and removed D5 from a proposed list of toxic substances under the Canada Environmental Protection Act (CEPA).
In addition, Environment Canada, having reviewed the environmental data available for D4, has not imposed any product use or concentration restrictions on the use of D4 in any application; they only require certain facilities that use D4 to prepare a pollution prevention plan to minimize the release of D4 in industrial effluents.
In November 2008, Environment Canada conducted a screening assessment on D6. Based on this assessment, Canada’s Environment Minister concluded that “D6 is not entering the environment in a quantity or concentration or under conditions that is harmful to the environment.”
The silicones industry worked with EPA to design a monitoring program that would produce the exposure data the agency needed to conduct a thorough and scientifically sound risk assessment for D4. Members of the Silicones Environmental, Health, and Safety Center (SEHSC) completed this environmental monitoring program to assess levels of D4 in the environment and submitted the final results to EPA in September 2017.
An independent peer-reviewed study of the monitoring program concluded that D4 does not harm the environment and that no further regulatory restrictions are warranted.
In Europe, siloxanes are assessed under the chemicals framework known as REACH. They have come under scrutiny because of a suspicion that some of them may be PBT (Persistent, Bioaccumulative, Toxic) or vPvB (very Persistent, very Bioaccumulative). However, the European criteria for assessing whether a substance is PBT or vPvB do not allow for accurate evaluation of the unique and hybrid nature of siloxanes. In fact, many leading scientific experts believe that current regulations define PBT in terms of overly rigid laboratory criteria that are based on the state of the science in the late 1970s and early 1980s, and do not reflect what is observed in the environment.
Restrictions (personal care and consumer and professional products)
Following a scientific assessment of the substances for possible PBT and vPvB properties by the United Kingdom, a restriction on the use of D4 and D5 was adopted under the European Union’s Chemicals management program (REACH) in May 2017.
The scope of the restriction is limited to wash-off cosmetic products with a D4 or D5 concentration equal to or greater than 0.1% by weight of either substance. All actors that place on the market products that are within the restriction scope must comply with the requirements set forth in this restriction by January 31, 2020.
In response to this restriction, the silicones industry set up a large-scale Waste-Water Treatment Plant (WWTP) monitoring program across five European states to determine current baseline influent concentrations and help assess the effectiveness of this restriction in reducing D4 and D5 down-the-drain emissions. Preliminary monitoring results indicate that D4 and D5 wastewater treatment plant influent concentrations are well below the baseline levels predicted in the Restriction Dossier, and in the case of D4, already consistent with the predicted post-restriction concentrations.
The silicones industry has filed a legal action against the EU that challenges the legal text that effectively prevented EU regulators from utilizing the wealth of data available for D4 and D5 when making their final determination of PBT/vPvB. The legal action is primarily about the regulatory assessment legal criteria which was used to provide the underlying justification for the restriction, not the restriction itself.
In April 2017, the European Chemicals Agency (ECHA) published its intention to assess the need for further restriction of D4 and D5 in leave-on personal care products and other consumer/professional uses (e.g. dry cleaning, waxes and polishes, washing and cleaning products).
In January 2018, the Commission requested adding D6 to the scope of this restriction, and to the scope of the ‘wash-off’ restriction. The restriction proposal on D4, D5, and D6 in leave-on products, as well as the addition of D6 to the 'wash-off' restriction was published in March 2019. The public consultation for this proposed restriction ends on September 20, 2019.
Substances of Very High Concern
Following a Risk Management Option Analysis (RMOA) of D4 and D5 in late 2017, Germany concluded that these substances meet the REACH criteria for PBT and vPvB and should be identified as Substances of Very High Concern (SVHC). In parallel, the Commission requested ECHA to develop a similar SVHC dossier for D6, based on the ECHA PBT Expert Group’s conclusion that D6 should be considered a vPvB substance.
Although a weight-of-evidence approach applied to all the available data shows that the actions of these regulatory bodies are overstated, the European Union Member State Committee added D4, D5, and D6 to the list of SVHCs in June 2018. The silicones industry maintains that the EU decision does not consider the whole body of scientific evidence and will ultimately put at risk numerous beneficial uses of silicones in key segments of the economy. The silicones industry has filed a legal action against the EU that challenges the decision of the European Chemicals Agency (ECHA) to include D4, D5 and D6 in the candidate list as SVHCs. The basis for this legal action is that ECHA did not consider all of the available information when it designated D4, D5 and D6 as SVHCs.
Formal identification of PBT/vPvB properties carries communication and risk management measure obligations. The complexity of this information varies according to the actors in the supply chain. More information on these obligations can be found on the ECHA website.
The silicones industry is working closely and on an ongoing basis with the value chain, the Commission, ECHA, and the authorities in European countries to encourage the use of updated PBT criteria and a weight-of-evidence approach for chemical assessments. The silicones industry strongly believes that the use of updated PBT criteria and a weight of evidence approach will provide the most accurate environmental assessments of D4, D5, and D6.
In December 2017, the Japan Chemical Substances Review Committee conducted a review on the classification of D4, D5, and D6 following the conclusion from the Ministry of Economy, Trade and Industry (METI) that D4, D5, and D6 meet the current criteria for Persistence and Bioaccumulative (PB) substances in Japan.
The Chemical Substances Review Committee concluded that D4 and D6 should be added to the Chemical Substance Control Law (CSCL) “monitoring chemicals” category as additional data are required to complete the assessment. Substances are included in this category if they are determined to be “persistent” and “bio-accumulative” but there are no restrictions on their use. No change was recommended for D5. Based on safety data, the committee concluded there is not a concern for D5 for human health or the environment. D5 will continue to be managed under the CSCL General Chemical category.