Environmental Decision Memo for Food Contact Notification No. 001366

Return to inventory listing: Inventory of Environmental Impact Decisions for Food Contact Substance Notifications or the Inventory of Effective Food Contact Substance Notifications.

See also Environmental Decisions.

Date: January 6, 2014

From: Biologist, Regulatory Team 2, Division of Biotechnology and GRAS Notice Review (HFS-255)

Subject: FCN No. 1366 – Polysiloxanes, di-Me, 3-hydroxypropyl Me, ethoxylated; (a.k.a. Siltech P-101), as a component of emulsion-based defoamers for the manufacture of food-contact paper and paperboard.

Notifier: Siltech Corporation

To: Vanee Komolprasert. P.E., Ph.D., Division of Food Contact Notifications (HFS-275)
Through: Annette M. McCarthy, Ph.D, Senior Science and Policy Staff____

Attached is the Finding of No Significant Impact (FONSI) for FCN 1366. After this notification becomes effective, copies of this FONSI and the notifier's environmental assessment, dated August 23, 2013, may be made available to the public. We will post digital transcriptions of the FONSI and the environmental assessment on the agency's public website.

Please let us know if there is any change in the identity or use of the food-contact substance.

Leah D. Proffitt

Attachment: Finding of No Significant Impact

File: FCN No. 1366


A food-contact notification (FCN No. 1366), submitted by Siltech Corporation, to provide for the safe use of polysiloxanes, di-Me, 3-hydroxypropyl Me, ethoxylated; (a.k.a. Siltech P-101), as a component of emulsion-based defoamers for the manufacture of food-contact paper and paperboard.

The FCS is intended for use as a component in emulsion-based defoamers that are used in the pulping of lignocellulosic materials. Such lignocellulosic materials can be used to make food-contact paper and paperboard that may come into contact with all types of food.

The FCS is incorporated at a rate 20 kg per 1000 kg of emulsion-based defoamer. The emulsion-based defoamer is added to the pulping process at rate of 10 ppm, which is equivalent to 0.2 ppm of the FCS.

In the paper lifecycle, there are three main waste-generating stages: pulp processing, paper manufacturing, and ultimate disposal of paper by the consumer. Over 99.9% of the FCS is expected to be lost in the aqueous components during pulp and paper processing such that only extremely low levels of the FCS will remain with the paper. The consumer is expected to dispose of food-contact paper according to nationwide disposal patterns, i.e. to landfills, recycling or to municipal waste combustion (MWC) facilities. Both landfills and MWC units are regulated and permitted by EPA, and operate under 40 CFR 258 (landfill requirements) and 40 CFR 60 (MWC air emission standards). Due to contamination with food residues, food-contact paper is not expected to be recycled to any great extent. Given the extremely small concentration of the FCS that is expected to remain with paper, and the controls in place to restrict environmental introductions from landfills and combustion, no significant environmental releases are expected from the proper disposal of end-use items to permitted landfills and MWC facilities.

Pulp Processing

Pulp processing yields a mixture of cellulose fibers and lignins; this mixture is washed to remove the lignins. This wash step is where defoamers, including those containing the FCS, are added. The resulting pulp (i.e. cellulose fibers) is sent through a series of washers, generating a liquid waste known as “black liquor.” 

The FCS is not substantive to pulp, and, therefore, will be dissolved in the liquid waste, such that only very small amounts will remain with the isolated pulp. Consistent with FDA’s chemistry guidance for water-soluble wet-end additives that remain in finished paper, it is estimated that 2% or less of the FCS added with the incoming wash water will remain with the pulp. As a result, approximately 98% of the FCS is expected to be lost with the black liquor process. As further support for this assumption, the following calculation is provided:

A typical pulp mill uses approximately 64 cubic meters (64,000 liters, or kg) of water per metric ton (1000 kg) of pulp. Thus, the mass of water is 64 times that of the pulp. Assuming the FCS partitions equally between the water and pulp phases, the amount of the FCS remaining in the isolated pulp will be 1/64th, or less than 2% of the amount added.

The black liquor is recycled through a series of drying and evaporation steps. Black liquor concentrate is then burned for energy and chemical recovery, and the remaining ash is dissolved in water to form “green liquor.” This green liquor is treated with calcium oxide to form “white liquor,” which is recycled back to the process. Standard industry practices will result in the combustion of the FCS with any byproducts being recycled back into the process.

The FCS is not expected to be released to the environment at the pulping site. This is due to its presence in the “black liquor,” which is recycled and reprocessed under conditions that are expected to cause the FCS to decompose. These conditions include evaporation at very high temperatures, such that all biomass is used for energy recovery and water vapor is recycled.

Following the washing process, the pulp fibers are sent to the bleaching line, where the pulp, containing 2% of the FCS, is isolated, dried and sold in fluff form to paper manufacturers.

Paper manufacturing:

In order to make paper from the pulp, it must first be re-dispersed in water to form a slurry. Any small amounts of FCS remaining with the pulp (i.e. 2% or less) are expected to be liberated from the fibers at this stage. The slurry is then subjected to a series of isolation steps which progressively reduce the water content of the paper. The resulting water is called “white water.” It is expected that, of the 2% FCS remaining with the pulp, 98% will partition to the white water.

Therefore, given the percent partition of the FCS to pulp and water, and the FCS use level of 0.2 ppm (20g/metric ton of pulp), the following calculations apply:

(20g FCS/metric ton pulp)(0.98)(0.02) = 0.39 g FCS/metric ton pulp*

*the EA mistakenly states that this is the amount in white water

0.39 g/metric ton pulp = 3.9 x 10-7g FCS/g pulp

Since the pulp slurry contains 0.5% pulp, the FCS concentration in the water is

(3.9 x 10-7g FCS/g pulp)(5 g pulp/1000 g water) = 1.9 x 10-9 g FCS/g water = 1.9 ppb.

Pulp and paperboard manufacturing are among those industries required to pre-treat their waste water to industry-specific standards (40 CFR 430) before discharging to publicly-owned treatment works (POTW). However, in the absence of chemical or biological breakdown data, the notifier assumes that waste water leaving the on-site pretreatment facility will contain 1.9 ppb of the FCS. Therefore, the environmental introduction concentration (EIC) is 1.9 ppb. Using a standard factor of 10, to account for dilution upon release to surface waters after POTW treatment, yields an effective environmental concentration (EEC) of 0.19 ppb.

An acute toxicity study of a higher molecular-weight version of the FCS (Silquat 3180) was provided as an appendix to the EA for FCN 784. In this study of Daphnia magna neonates (< 24 hours old), the 48-hour EC50 was 6.6 ppm and the 48-hr NOEC was 2.5 ppm. These levels are well above the EEC of 0.19 ppb for the proposed use. Even if we were to add a margin of safety to account for the difference in chemical structure, the risk assessment does not indicate a risk to any species from the proposed use.

Therefore, we do not expect significant environmental impacts from the proposed use of the FCS.

Prepared by       __________________________________________Date: January 6, 2014
Leah D. Proffitt
Office of Food Additive Safety  
Center for Food Safety and Applied Nutrition
Food and Drug Administration

Approved by      __________________________________________Date: January 6, 2014
Annette M. McCarthy, Ph.D.
Senior Science and Policy Staff
Office of Food Additive Safety
Center for Food Safety and Applied Nutrition
Food and Drug Administration

Page Last Updated: 12/31/2014
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