CUYAHOGA FALLS, Ohio—Though regulatory measures worldwide continue to pose obstacles for the silicone industry, there are a few bright spots on the horizon, according to Alexandra Rinehart, regulatory engineer at Shin-Etsu Silicones of America Inc.
Rinehart presented an update on global regulations for silicones through the Silicones Environmental, Health and Safety Center at the International Silicone Conference, held April 10-11 in Cuyahoga Falls, Ohio.
The SEHSC, an American Chemistry Council group, is meant to promote the safe use of silicones through product stewardship and environmental health and safety research, she said.
"Simply put, we want to give regulators the best peer-reviewed science available to make appropriate regulatory decisions on our materials," Rinehart said.
The group is made up of North American silicone producers and importers including Dow Corning Corp., Elkem Silicones, Evonik A.G., Milliken & Co., Momentive Performance Materials Holdings Inc., Shin-Etsu and Wacker Chemie A.G.
As a group, SEHSC advocates that countries conduct their own assessment of octamethylcyclotetrasiloxane (D4), using risk-based weight-of-evidence approaches. Risk-based methodology uses previous analysis to prioritize assessment based on risk. A weight-of-evidence approach takes into account a wider range of evidence, as opposed to a strength-of-evidence approach, which uses evidence with a narrower focus.
The group also advocates risk-based determinations for state chemical assessments, and for state recognition of the U.S. Environmental Protection Agency as the primary authoritative regulatory entity for chemical assessment in the U.S., Rinehart said.
In the U.S. on the federal level, the SEHSC completed a consent agreement in September 2017 in conjunction with the EPA to generate real-world monitoring data for D4 environmental exposure to water following discharge from waste water treatment facilities, Rinehart said.
"Actual environmental concentrations measured in samples collected during the program will facilitate EPA's environmental risk assessment for D4," she said.
Monitoring was conducted at municipal and industrial waste water treatment facilities with discharges to surface waters, and an independent, peer-reviewed environmental risk evaluation of the data concluded that environmental exposure to D4 poses no unreasonable risk and no regulatory restrictions are needed, she said.
"EPA has indicated that it will use this robust data set to conduct its environmental risk assessment of D4," she said. "This real-world data will help ensure the agency will rely on more accurate exposure data rather than simply modeling for D4."
By state, Washington originally had listed D4 for alleged endocrine factors, but it was delisted due to weight of evidence, Rinehart said.
"It was a very big win for the silicone advocacy in conjunction with ACC efforts," she said.
In Oregon and Vermont, D4 is listed as "persistent, biocumulative and toxic"—or PBT— because of applying criteria without consideration of exposure, she said. Similarly, Maine has D4 and decamethylcyclopentasiloxane (D5) both listed as PBT, because of lack of consideration of exposure. Dodecamethylcyclohexasiloxane (D6) was delisted because of no rulings by an authoritative body. In Minnesota, D5 and D6 are listed as PBT because of inclusion on hazard-based lists.
Rinehart said regulatory determinations made in the U.S. under the reformed Toxic Substances Control Act (now the Lautenberg Chemical Safety for the 21st Century Act), which gives EPA the authority to require reporting, record-keeping and testing requirements and restrictions relating to chemical substances, should be used preferentially by U.S. states for chemical of concern lists.
In Europe, activity has been busy as of late, she said. There is a restriction of D4, D5 and D6 in personal care products, not to be formulated, placed on the market or used directly in wash-off products after January 2020. The restriction applies to products with a concentration of D4, D5 or D6 in an excess of 0.1 percent.
The Stockholm Convention is an international environmental treaty that aims to eliminate or restrict the production of persistent organic pollutants, and the European Union did nominate D4 as a POP in 2017, but it was not approved, Rinehart said.
"We also believe that D4 will be nominated again as a POP in 2018, and we will continue to monitor and advocate against this," she said. "The silicone industry position is such that a risk-based weight-of-evidence assessment of D4 with appropriate considerations for environmental exposure illustrates that D4 is not a POP and does not warrant any regulatory restrictions."
The European Chemicals Agency announced public consultation on substances of very high concern including D4, D5 and D6, Rinehart said. As of March 2018, EU members have proposed all three chemicals as SVHCs. If that proposal is supported by EU member states, a final SVHC decision could be made as early as June 2018.
The EU also proposed additional restrictions of D4, D5 and D6 in leave-on personal care products and other consumer and professional uses, such as dry-cleaning, waxes and polishes, washing and cleaning products. The SEHSC's position is that the additional restrictions are premature and unjustified, and current regulations should be fully implemented before new ones are issued, she said.
As a "ray of sunshine and hope," Australian activity is "actually going very well," she said. Using risk-based assessment of siloxanes, Australia concluded the direct risk to aquatic life from exposure to the chemicals at expected surface water concentrations are not likely to be significant. Australia has not proposed any regulatory restrictions on these materials.
In Japan, D4 was assigned to the chemical substance control list in the monitoring chemicals category because certain ecotoxicity data was not available. The category refers to existing chemicals that are confirmed to be consistent and biocumulative, and requires manufacturers and importers to complete reporting on usage amounts and other information as well as potential pollution prevention guidelines, Rinehart said.
D5 will continue to be managed under the CSCL under the general chemical category, and D6 was included in the monitoring chemicals category. The effective date for the categorization is expected to be sometime in April. Monitoring studies to measure the concentrations of D4, D5 and D6 in Tokyo Bay continue under the silicones industry voluntary product stewardship program.
In China, the Ministry of Ecology and Environment removed D4 from the draft list of prioritized chemicals, and the D4 risk assessment will begin sometime in April. The risk-based assessment will be conducted by three parties: the global silicones industry, the Chinese silicones industry and the Chinese government, she said.
If regulations regarding D4, D5 and D6 proceed for downstream products like silicone rubber, "there could be some pretty serious repercussions," Rinehart said. "There could be product restrictions in the EU, and that would be gradual concentrations where you would not want more than a certain amount, probably more than 0.1 percent in your formulations. Or it could be as problematic as a complete restriction on these products.
"D4 and D5 are very key, critical components to silicone polymers, so that could be a real problem. Which is why we're working so closely with the regulators to combat that."