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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 Study Plan Review_03062014 FINAL.pdf

John, 

As we discussed last Friday, the PCBTF Testing Consortium is working with Harlan Laboratories to re-conduct 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 submitted by the PCBTF Testing Consortium, all of the Agency’s 

substantive comments were related to the test material’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 concentrations 

would be prepared individually (in different vessels) 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 dilutions of a stock 

solution. EPA, on the other hand, referenced the OECD guidance document, Aquatic Toxicity Testing of Difficult 

Substances and Mixtures, which states that the concentrations should be individually prepared. OECD Series on Testing 

and Assessment Number 23 at p. 27. 

Harlan Laboratories continues to recommend the serial dilution method because preparing individual stock solutions 

does not allow for, and likely will not achieve, proper spacing of the five concentrations. Preparing five individual 

concentrations, as proposed by EPA, would likely result in obtaining five different concentrations without any 

reasonable spacing between the concentrations. For example, you could theoretically could get five solutions all with 

the same concentration of PCBTF. In order to prepare any solution of PCBTF, you must add an excess and force it into a 

saturated solution. The lab recommends diluting this saturated solution so that there is at least some measure of control 

over the concentration. (Alternatively, adding a lesser amount (i.e., non-saturated solution) and attempting to prepare 

concentrations individually does not ensure that the material is even getting into solution and reduces the lab’s ability to 

effectively control the test concentrations.) 

In short, you stand a much better chance of having reasonably spaced concentrations by the serial dilution method 

proposed by the lab in order to attain the target concentrations. In using either method, the lab will still measure the 

amount of test material that goes in the test vessel. 

The PCBTF Testing Consortium requests concurrence and approval from EPA on the use of dilution of a stock solution 

(i.e., serial dilutions) as set forth in the study plan. 

Issue-2 

Issue-1 above raises the broader issue of whether conducting the algae test is even practical and makes sense from a 

risk assessment perspective. Specifically, if PCBTF is expected to volatilize from water so rapidly because of its 

insolubility and high vapor pressure, then what practical purpose can be derived from performing this test? Indeed, the 

same OECD guidance states that “Algal tests with very volatile substances are technically very difficult to perform 

satisfactorily and may as a consequence yield results that are difficult to interpret and of limited relevance 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 predicted Henry’s Law 

Constant of 0.0347 atm-m3

/mole (3,520 Pa-m3/mole). The combination of these two physical properties has made 
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testing of the compound technically very challenging. Indeed, the OECD guidance states that: “As an approximation, 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 may become significant for substances with Henry’s law constants of 1-

10 Pa.m3/mol under vigorous mixing conditions where the opportunity for water/air exchange is high.” Id. at p. 26. 

Under these conditions, it becomes very difficult to quantify the results or at the very least have reliability in those 

results. 

It is also noted that every substantive comment in EPA’s March 6, 2014 response pertains to the volatility/water 

insolubility issue. Undertaking such long list of significant efforts to perform this test – as enumerated in those 

comments – in and of itself calls into question whether 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 consideration 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