The silicone industry is committed to the responsible use of silicones and international environmental stewardship. The industry continues to evaluate the science behind its materials and monitor the presence of substances in the environment through robust environmental monitoring programs.
To provide the U.S. Environmental Protection Agency (EPA) with environmental monitoring data on one of the basic substances used to make silicones, the siloxane D4, in March 2016 members of the SEHSC began an environmental monitoring program, designed in partnership with EPA, to assess levels of D4 in the environment. In September 2017, members of SEHSC submitted the final results of its D4 environmental monitoring program to EPA. 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.
Global governments are using real-world data to drive the chemical assessments. For example, Environment Canada reviewed the scientific data and environmental monitoring results available for D4 and determined that no restrictions needed to be imposed on product use or product concentration limits on the use of D4 in any application; Canada only requires certain facilities that use D4 to prepare a pollution prevention plan to minimize the release of D4 in industrial effluents.
Canada’s Minister of the Environment also ruled that no regulatory restrictions on the siloxane known as D5 need to be imposed after it was found by an independent panel of expert toxicologists to pose no risk to the environment now, or in the future. Canada’s review of D6 found that D6 also does not pose a risk to the environment and requires no regulatory restriction.
In addition, Australia’s Department of the Environment and Energy has carried out a risk assessment for a range of silicone materials which is consistent with Canada’s assessment and risk management decisions 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.
In Europe, the existing criteria for assessing whether a substance is PBTor vPvB do not allow for accurate evaluation of siloxanes. In fact, many leading scientific experts believe that current regulations define PBT in terms of overly rigid criteria that are based on the state of the science in the late 1970s and early 1980s. The silicones industry is working closely with 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.
As part of the industry’s commitment to product stewardship, the silicones industry set up a Monitoring Program for D4 and D5 in 2010. The Silicones Monitoring Program takes place in four different locations around the world to provide a representative picture of the silicone materials’ fate and distribution, i.e. Lake Pepin in the United States; Lake Ontario in Canada; Osloforjd in Norway; and Tokyo Bay in Japan.
The Silicones Monitoring Program consists of three main parts:
- Evaluating emissions from wastewater treatment plants (WWTP) by determining the effectiveness of WWTP and the representative concentrations of D4 and D5 releases;
- Long-term monitoring program for D4 and D5 in surface sediment and aquatic biota to determine if concentrations are stable or changing over time; and,
- State-of-the-art modelling techniques for accurate predictions of a large number of similar locations.
To date, monitoring studies have shown no increase in siloxanes environmental concentrations despite increased use over the past years.
The silicones industry also established a monitoring program for D4 and D5 in Europe to assess the effectiveness of the European Union’s ‘Personal Care wash-off product” restriction on down-the-drain emissions of D4 and D5. Concentrations of D4 and D5 are being monitored over time in influent wastewater from residential sources in the EU.
This monitoring program consists of 24 sampling events at 6 regionally different residential WWTPs in Europe during 3 distinct periods: pre-restriction, phase-out; and post-restriction.
To date, preliminary monitoring results indicate that D4 and D5 WWTP influent concentrations are lower than those predicted.