CUYAHOGA FALLS, Ohio—Labeling certain siloxanes as persistent organic pollutants is not warranted and would have a significant impact on the silicone industry, one industry official said.
As environmental and regulatory supervisor for Shin-Etsu Silicones of America Inc., Alexandra Rinehart explained how siloxanes are viewed in the regulatory environment during a presentation at the International Silicone Conference, being hosted virtually by Rubber & Plastics News Nov. 10-12.
Rinehart, who also serves as chair of the Regulatory and Public Affairs Committee of Silicones Environmental, Health and Safety Center within the American Chemistry Council trade group, provided an overview of how siloxanes are viewed in different parts of the world by regulators. She also highlighted the differences between countries and even between states.
She spoke about three different siloxanes known as D4, D5 and D6, and what impact their further regulation could have on the industry.
"Overall, it's important for all regulators to know that siloxanes, particularly D4, D5 and D6, which we discussed today, are safe. There is a wealth of science that confirms that siloxanes do not behave like PBTs (persistent, bioaccumulative and toxic substances) in the environment," she said.
"Second, no regulatory restrictions are warranted. Lastly, siloxanes provide countless, invaluable and unique benefits, primarily as indispensable building blocks to produce silicone," Rinehart said. This is true for both consumers and "innovative solutions" for society at large.
While certain states addressing siloxanes have different criteria, Rinehart said they face difficulties in making their determinations. "The challenges for identifying COCs (chemicals of concern) in the U.S. are that many states don't actually have the resources to conduct scientific evaluations.
"Therefore, the states rely on evaluations conducted by an 'authoritative government entity.' It's a very broad description. The basis for authoritative government entities are not consistent state by state. Some government entities use risk-based determinations. Others use hazard-based determinations to classify," Rinehart said.
Siloxanes are building blocks used in the creation of silicones, but there have been concerns raised about their use and what impact they have on the environment and on humans.
"Overall,," Rinehart said, "silicone policy advocacy boils down to three main points. One, current modeling programs are not indicative of the fate and exposure of silicone chemistry. Therefore, empirical monitoring data is critical for our compounds. Two, single criteria should not be relied upon exclusively for hazard determination. And three, data and monitoring information should be used collectively in the weight of evidence assessment of risk."
In November 2019, the European Union Persistent Organic Pollutants Competent Authority reviewed priority substances for 2020 Stockholm Convention POP nominations. While D4 was mentioned, member states did not support making it a priority for 2020, Rinehart said.
Just in June, the POP Competent Authority reviewed substances for 2021 and beyond. "D4 remains on the list, but interventions by Member States indicate that this is not a priority at this time," Rinehart said.
Putting D4 on the POP list would be "significant and devastating to our industry," Rinehart said. "This would result in a global ban of D4 from commerce, which would have wide, disproportionate and unjustified implications."
"This would, of course, negatively impact the use of silicone polymers for which D4 is an essential building block. None of the innovative applications from silicone polymers, from renewable energy technologies to transportation safety, would be possible," she said.