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### Schaeffer, John

From: John V. Massingale <john@grcci.com> Sent: Monday, August 11, 2014 4:59 PM To: Schaeffer, John Subject: PCBTF [CAS RN 98-56-6] (HPV3) Attachments: OECD-23_difficult_substances.pdf; 98-56-6_Algae Stu dy Plan Review_03062014 FINAL.pdf

John,

As we discussed last Friday, the PCBTF Testing Cons ortium is working with Harlan Laboratories to re-co nduct the algae study on PCBTF [CAS RN 98-56-6] (HPV3). This e-mail addresses two issues associated with this test.

Issue-1

In EPA’ s comments dated March 6, 2014 on the test plan sub mitted by the PCBTF Testing Consortium, all of the Agency’s
substantive comments were related to the test mater ial’s high volatility and limited water solubility, and how these properties may affect the conduct of the algae test . Once such comment pertained to whether the five c oncentrations would be prepared individually (in different vessel s) or by dilution of a saturated stock solution (i. e., serial dilutions). See Comment 7. In the submitted study plan, the Harlan Laboratories recommended the use of serial dilution s of a stock solution. EPA, on the other hand, referenced the OE CD guidance document, Aquatic Toxicity Testing of Difficult
Substances and Mixtures , which states that the concentrations should be in dividually prepared. OECD Series on Testing and Assessment Number 23 at p. 27.

Harlan Laboratories continues to recommend the seri al dilution method because preparing individual sto ck solutions does not allow for, and likely will not achieve, pr oper spacing of the five concentrations. Preparing five individual concentrations, as proposed by EPA, would likely re sult in obtaining five different concentrations wit hout any reasonable spacing between the concentrations. For example, you could theoretically could get five sol utions all with the same concentration of PCBTF. In order to prepar e any solution of PCBTF, you must add an excess and force it into a saturated solution. The lab recommends diluting thi s saturated solution so that there is at least som e measure of control over the concentration. (Alternatively, adding a le sser amount (i.e., non-saturated solution) and atte mpting to prepare concentrations individually does not ensure that th e material is even getting into solution and reduce s the lab’s a bility to effectively control the test concentrations.)

In short, you stand a much better chance of having reasonably spaced concentrations by the serial dilu tion method proposed by the lab in order to attain the target c oncentrations. In using either method, the lab will still measure the amount of test material that goes in the test vesse l.

The PCBTF Testing Consortium requests concurrence a nd approval from EPA on the use of dilution of a st ock solution (i.e., serial dilutions) as set forth in the study plan.

Issue-2

Issue-1 above raises the broader issue of whether c onducting the algae test is even practical and make s sense from a risk assessment perspective. Specifically, if PCBTF is expected to volatilize from water so rapidly be cause of its insolubility and high vapor pressure, then what pra ctical purpose can be derived from performing this test? Indeed, the same OECD guidance states that “Algal tests with ve ry volatile substances are technically very difficu lt to perform satisfactorily and may as a consequence yield resul ts that are difficult to interpret and of limited r elevance to real-world conditions.” Id. at p. 27.

Because of the compound’s very high volatility and very low water solubility, PCBTF has a high predict ed Henry’s Law
Constant of 0.0347 atm-m 3 /mole (3,520 Pa-m 3 /mole). The combination of these two physical prope rties has made2 testing of the compound technically very challengin g. Indeed, the OECD guidance states that: “As an ap proximation, if H is greater than 100 Pa.m3/mol, more than 50% of the substance could be lost from the water phase in 3- 4 hours (Mackay, 1992)...The losses due to volatilisation m ay become significant for substances with Henry’s l aw constants of 1- 10 Pa.m3/mol under vigorous mixing conditions where the opportunity for water/air exchange is high.” I d. at p. 26. Under these conditions, it becomes very difficult t o quantify the results or at the very least have re liability in those
results.

It is also noted that every substantive comment in EPA’s March 6, 2014 response pertains to the volati lity/water insolubility issue. Undertaking such long list of s ignificant efforts to perform this test – as enumer ated in those comments – in and of itself calls into question whe ther this study should even be performed as part of the TSCA Section 4 test set for PCBTF. Therefore, the PCBTF Testing Consortium requests that EPA give every considerati on to eliminating this test from the required tests.

Thank you.

John

_______________________________
John V. Massingale Greenwich Chemical Consulting, Inc. 3300 PGA Boulevard, Suite 635 Palm Beach Gardens, FL 33410
T 561.578.8110
F 561.578.8120 E john@grcci.com www.grcci.com