Page 1 of 4 December 1, 2014

Fred Jenkins, Jr., Ph.D. Designated Federal Official FIFRA Scientific Advisory Panel Staff USEPA/OSCP (7201M) Environmental Protection Agency 1200 Pennsylvania Ave., N.W. Washington, DC 20460–0001

Dear Dr. Jenkins:

RE: FIFRA SAP Meeting, Integrated Bioactivity and Exposure Ranking – A Computational Approach for the Prioritiza tion and Screening of Chemicals in the Endocrine Disruptor Screening Progr am; Docket ID EPA–HQ–OPP–2014–0614.

These comments are submitted on behalf of People for the Ethical Treatment of Animals, the Physicians Committee for Responsib le Medicine, and the Humane Society of the United States – national animal protection and scientific advocac y organizations with a combined constituency

of more than 13 million Americans who share the common goal of promoting reliable and relevant regulatory testing met hods and strategies that protect human health and the environment while reducing, and ultimately eliminating, the use of animals.

We appreciate the opportunity to comment on the wh ite paper that is the subject of this FIFRA Science Advisory Panel (SAP) meeting, i.e., th e Integrated Bioactiv ity and Exposure Ranking computational approach for use in prioritization and screening of in the Endocrine Disruptor Screening Program (EDSP).

General Comments

Our organizations are very impressed with and a ppreciative of the amount of work that the EPA has performed in developing and implementi ng computational and high throughput screening (HTS) tools to predict both chemical activity in the estrogen receptor (E R) and androgen receptor (AR) pathways and environmental exposure. We are excited about the progress that has been made and the strong likelihood that these tools ma y soon be ready to replace the uterotrophic and Hershberger EDSP Tier 1 in vivo assays, as well as the ER and AR receptor binding assays that,

while considered to be in vitro assays, rely on the collection and use of animal tissues.

There are two important improvements over th e current EDSP encapsulated by the proposed approach: the evaluation and pr esentation of chemical activi ties as probabilities, and the inclusion of exposure estimates in prioritiza tion (i.e. Integrated Bioactivity and Exposure Ranking (IBER). Such approaches to prioritizi ng and screening the unive rse of EDSP chemicals will lead to a better understanding of the potentia l endocrine activity of the broad spectrum of

chemicals in the EDSP chemical universe as well as to a more efficient and more humane way to rapidly identify those substances that have the greatest potential of causing adverse effects inPage 2 of 4 human and wildlife populations, and ultimately resu lt in the use of far fewer animals in testing

under the EDSP.

The ability of HTS screening to replace the mechanistic in vivo Tier 1 assays (i.e. the uterotrophic assay) is promising. The EPA shoul d consider additional ways the information

could be used to avoid in vivo testing. For example, as described in the white paper, the utility of

the in vivo Tier 1 uterotrophic and Hershberger assa ys appears to be related to chemical

activation and detoxification. Ther efore, it may be possible in the near-term to skip Tier 1 altogether and move on to further evaluation if it can be shown th at detoxification is unlikely to play a role in high-IBER scoring chemicals. In addition, as the HTS assays improve and expand coverage and the IBER approach evolves, the true utility of other Tier 1 assays must continue to

be reassessed.

While we understand that the focus of the EDSP SAP meetings is on the adequacy and appropriateness of the science, there is often an accompanying lack of clarity with regards to policy – in this case a description of exactly how IBER results will be used to inform decisionmaking for purposes other than prioritization, such as informing additiona l Tier 1 and Tier 2 testing. Because of the large animal numbers invo lved, particularly in Tier 2, consideration of how these methodologies will be used to inform fu ture testing decisions is integral to this ongoing discussion. For example, does the EPA inte nd to require Tier 2 testing for high-ranking IBER chemicals, or would another level of interm ediate testing be considered to further exclude chemical substances? Suggestions have been ma de for more nuanced tiering or integrated strategies, including addition of a “Tier 1.5” 1 or use of a strategy based on the OECD Conceptual Framework, 2 which could provide a basis for appl ying IBER information, along with Other Scientifically Relevant Information (OSRI) to inform potential further testing. Can the EPA envision situations in which regu latory decisions could be made with IBER and Tier 1 assays, avoiding Tier 2 altogether? We urge the Agency to consider, and share with the public, how screening results from these met hodologies could inform a more in tegrated approach to testing

and assessment.

Specific Comments

1. Consideration of receptor-specific activity vs. potential “pseudo-receptor” activity (Table 2.3 and 2.4, discussion on page 37) as well as representation of chemical activity as a probability (e.g. of agonist or antagonist ac tivity) is particularly helpful in providing additional information regarding uncertainty and/or specificity of chemical behavior and provides a clear advantage of the HT S approach vs. conventional testing.

1 Juberg,	D.R.,	Borghoff,	S.J.,	Be cker,	R.A.,	Casey,	W.,	Hartung ,	T.,	Holsapple,	M.P.,	Mart y,	M.S.,	Mihaich,	E.M.,	Van Der	Kraak,	G.,	Wade,	M.G.,	Wille tt,	C.E.,	Andersen,	M.E.,	Borge rt,	C.J.,	Coady,	K.K.,	Dourson,	M.L.,	Fowle	III,	J.R., Gray,	L.E.,	Lamb,	J.C.,	Ortego, L.S.,	Schug,	T.T.,	Toole,	C.M., Zorrilla,	L.M.,	Kroner,	O.L.,	Pa tterson,	J.,	Rinckel,	L.A., and	Jones,	B.R.		(2014).		Lessons learned,	challenges	and	oppor tunities:		The	U.S.	Endocrine	Disruptor Screening	Program.	ALTEX		31,	63‐78.

2 Bishop,	P.L.	and	C.E.	Willett. (2013).	The	Use	and	Acceptance of	Other	Scientifically	Relevant	Information (OSRI)	in	the	U.S.	Environmental Protection	Agency	(EPA)	Endocr ine	Disruptor	Screening	Program.	Birth Defects	Res	B	Dev	Repr od	Toxicol.101(1):3‐22;	Juberg,	D.R.,	Geh en,	S.C.,	Coady,	K.K.,	LeBaron,	M.J.,	Kramer, V.J.,	Lu,	H.,	and	Marty,	M.S. (2013).	Chlorpyrifos:	Weight	of Evidence	Evaluation	of	Potential	Interaction	with the	Estrogen,	Androgen,	or	Thyroid	Pathway.		Regul.	Toxicol.	Ph armacol.		66,	249‐263.Page 3 of 4 2. With respect to the ER model’s concordance with results of reference chemicals run in the uterotrophic assay (p.50), the false negative and false positive rates of less than 10%

are excellent. The two chemicals that were not predicted correctly appear to be activated or de-activated by metabolic processes not available in the HTS assays used. This

underscores the need for more work on reliable methods that incorporate metabolism into the testing system. We urge the EPA to continue its investigation in this area and to make it a priority for future work.

3. On page 52, there is mention of a concor dant mathematical relationship between in vitro

AUC values and the level of in vivo potency in the uterotroph ic assay. We suggest that the EPA further investigate whether this relationship is maintained between the ER pathway model and higher-tier tests in order to facilitate avoidance of Tier 2 testing and move closer to using in vitro and in silico approaches for risk assessment. The development of metabolism and toxicokinetic mo dels as described la ter in the paper are an important part of this goal, but lack of su ch models need not be a barrier to using the ER pathway model for quantitative prediction in appropriate cases.

4. There appears to be a sma ll error on pp. 58-59 with refere nce to Figure 2.8. From the sequence of figures, the figure number should probably be 2.16.

5. We see real value in the prioritizing of chemicals for further testing by adding the exposure element to the model. On p. 59, 73 out of about 1,800 chemicals were predicted to have ER activity above the AUC cut-off designated for positive estrogen activity. This number was reduced to just six afte r applying IBER ranki ngs (Fig. 6.5, p.97), highlighting this approach’s utility in focusi ng attention on only those chemicals with the most potential for adverse effects.

6. Understanding that the work on the AR model is not as far along as that for the ER, we feel greater clarificat ion is needed for the statements on p. 75: “The AR pathway analyses are currently underway and at this time, we propose that adequate confidence has been demonstrated only for the first goal (prioritization). Additional resolution of performance of the AR models and potent ial utility for contributing to the weight of evidence determination of AR bioactivity will likel y be improved by adding additional reference chemicals.” As no timeframe is given in th e white paper for the completion of the AR work, we question why results of the AR appro ach could not be used in the short term as part of a WOE, particularly if OSRI is av ailable for a particular chemical that is

concordant with those results. It is possible the informati on on AR bioactivity gathered thus far could be used to help inform d ecisions about List 2 chemicals and we hope it could be utilized for that purpose.

7. We note the value of the current efforts in helping to identify and prioritize what additional exposure and biomonitoring data will be needed for better predictions of human exposure to chemicals (pp. 84-85). This will hopefully assist in directing and focusing monitoring efforts to provide more usef ul in the future. As the Agency is aware,Page 4 of 4 improved biomonitoring is a corner stone of the 2007 National Academies Toxicity Testing in the 21 st Century report.

8. With respect to the work being descri bed on the thyroid pathway (p. 99), we acknowledge the EPA as an international leader in attempts to model this pathway and develop useful assays but would also encour age Agency staff to stay engaged with the OECD and global efforts 3 in order to maximize and speed progress in this area and enhance development of the model.

9. We are pleased to see there are plans to model the various other pathways, e.g., steroidogenesis, cell stress, etc., and that th e EPA will initiate systematic reviews and curation of the pubertal, AMA, and fish repr oduction assays, and look forward to future presentations of these analyses at upcoming SAP meetings.

We are truly excited by the enormous strides th e EPA is making in developing and implementing

21 st century toxicology and risk as sessment methods and the eventu al effect this will have on both reducing the use of animals in regulatory te sting and increasing the efficiency and accuracy of identifying chemicals of concern.

Sincerely,

Patricia L. Bishop, MS

Research Scientist Regulatory Testing Division People for the Ethical Treatment of Animals

Kristie Sullivan, MPH Director, Regulatory Testing Issues Physicians Committee for Responsible Medicine

Catherine Willett, PhD Director, Regulatory Toxicology, Ri sk Assessment and Alternatives The Humane Society of the United States

3 Murk	AJ,	Rijntjes	E,	Blaauboer BJ,	Clewell	R,	Crofton	KM,	Ding emans	MM,	Furlow	JD,	Kavlock	R,	Köhrle	J, Opitz	R,	Traas	T,	Visser	TJ,	X ia	M,	Gutleb	AC.		(2013).	Mechani sm‐based	testing	strategy	using	in	vitro approaches	for	identification	of	thyroid	hormone	disrupting	che micals.		Toxicology	in	Vitro	27	(2013)1320–

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