January 20, 2016
Toxics Use Reduction Institute Science Advisory Board Meeting Minutes
January 20, 2016
Tufts Dental School - Room 1533, 1 Kneeland Street, Boston
12:30 PM
Members: Larry Boise (Vice-Chair), Dave Williams (Chair), Christy Foran, Ken Weinberg, Christine Rioux
Program Staff: Mary Butow (TURI), Tsedash Zewdie (DEP), Heather Tenney (TURI), Rich Bizzozero (OTA)
Other attendees: Denise Kmetzo (Collaborative Risk Solutions), Trisha McCarthy (Coyne PC for ACC), Margaret Gorman (ACC), Kathy Plotzke (SEHSC), Tracy Guerrero (SEHSC), Wendy Koch (SEHSC)
Members Not Present: Hilary Hackbart, Amy Cannon, Robin Dodson
Welcome and Introductions
Program Updates
- TURI held its Continuing Education Conference on November 19th. It went well.
- Resource Conservation Day 1 was January 13th & Day 2 is January 27th.
- The Advisory Committee meeting is February 4th.
- OTA is running a series of auto shop repair trainings on safer practices/alternatives, titled MASSCAR, throughout January and February.
Approve November Meeting Minutes
A vote could not take place due to lack of a quorum. A note was made to add the Administrative Council DPH designee to the list of Administrative Council members.
D5 Discussion
The Silicones Environmental, Health, and Safety Center, a sector group of the American Chemistry Council (SEHSC) gave a presentation for the Board focused on the Board’s questions about D5 from the last meeting. Key points of the SEHSC presentation:
- D5 acting as a Dopamine agonist was an early hypothesis. SEHSC stated that D5 is not a dopamine receptor agonist – it might be receptor agonist-like with downstream effects.
- The F344 strain used in an effort to conduct standardized studies. This particular substrain was found to be very different, with a higher background incidence of carcinomas.
- SEHSC commented on use of the BCF (Bioconcentration Factor) and how it relates to biomagnifications. The original objective was to protect against what happened with PCBs (highly lipophilic; poorly soluble; and don’t metabolize) and to protect against biomagnification. D5 metabolizes and doesn’t tend to biomagnify up the food chain. SEHSC cited the Gobas study showing lower levels as you go up the food chain. The solubility limits how much can be accumulated.
A Board member asked if there were any epidemiologic studies of people who work with D5. SEHSC stated that there are no classic epidemiological studies. There are epidemiologic studies available about people who work with silicones.
A Board member asked if D5 was on Prop 65 in California and it was confirmed that it is not.
Mary read an excerpt from ECHAs comments on D5. Specifically, “The DS concluded that D5 meets the Annex XIII criteria for vB based on the fish BCF, and supported by the other available data, particularly trophic magnification and the detection of D5 in wildlife at high concentrations” (ECHA 2015). SEHSC commented that there are no reported studies of exposure to organisms in remote regions that have no point sources. The Canadian Board of Review notes that because of the chemical/physical properties of D5, they don’t expect higher concentrations due to steady state.
A Board member asked what the degradation products are. SEHSC commented that they are primarily silanol materials. The methyl groups get cleared. There is further break down to silica (silicon dioxide) and carbon dioxide. A program member asked if they are totally demethylated. SEHSC commented that they are not totally demethylated, they keep breaking down into silanols. In humans the methyl group goes to CO2. A program member asked if methanol is a breakdown product. SEHSC said it is not. SEHSC commented that silanols only show toxicity at very high doses. Risk assessment shows 0.05% absorption.
With dermal absorption, it is excreted as parent material. In the liver, it is metabolized to water soluble silanols and ends up in urine, however often it is exhaled through the lung.
A Board member asked what the effect on membrane fluids and cAMP is. Endocrine systems are very tightly controlled. What is recovery like? Does it go back to baseline or do you get something different? One of the studies indicates that you get something different than baseline. A Board member asked what the physiological pulse is? With repeated exposure, do you get something physiologically different than baseline? SEHSC commented that researchers had to drive to extremely high doses to see slight changes. Siloxanes are gone a few hours after exposure. SEHSC commented that you would never get those high dose exposures. A question was asked about worker exposure. The Gentry risk assessment had listed occupational inhalation in certain industries as a concern.
A 1-page overview GreenScreen for D5 was distributed to the Board; the full report will be made available when it is published.
Heather reviewed the origin of this question to the Board, which was the inquiry from GreenEarth (licenses D5 use as a dry cleaning fluid) this past summer. We agreed that it was a good time for the SAB to review new information since 2011 on D5. Questions before the board on D5 are a) an assessment of the hazards and concerns so that TURI can share that information with companies and planners to inform decisions, and b) whether sufficient information and concerns exist that D5 should be added to the TURA chemical list.
The Board questioned what the trends of use in this substance are. SEHSC noted that use is increasing. The Board asked if TURI can update the Dry Cleaning Alternatives Assessment document with additional information from this review; Program staff indicated that TURI can.
New information for D4
Program staff noted the handouts for D4. The Board should let TURI know if they want any of the items listed in the literature review tables, or the EHS Summary. One Board member requested the Chemosphere article from Wang 2013. There was a comment about whether they were continuing to see D4 in adipose tissue. A question about the uses for D4 was raised. SEHSC noted it is mainly an intermediate for the production of polymers. This conflicted with current data from HSDB that notes several uses beyond intermediates. SEHSC will provide use data. It was also noted that monitoring from the EPA ECA on D4 should begin in April 2016. SEHSC will provide additional information on D4 for the March Meeting. SEHSC noted that there may be small amounts of D4 in D5. D4 is more volatile.
Next Meeting
March 30th, 2016 12:30 PM Location TBA
Handouts
D5 GreenScreen Summary
D5 SEHSC presentation
D5 Safety Review from SEHSC
D4 EHS Summary
Vieira 2012 D4 study summary table
Bibliography
ECHA 2015: Opinion on persistency and bioaccumulation of Octamethylcyclotetrasiloxane (D4), 556-67-2 & Decamethylcyclopentasiloxane (D5), 541-02-6 according to a MSC mandate. Adopted on April 22, 2015. European Chemicals Agency.