what information fulfills edsp screening requirements?
DESCRIPTION
What Information Fulfills EDSP Screening Requirements?. Steve Levine, Ph.D. Science Fellow Ecotoxicology & Risk Assessment Monsanto Company ISRTP Meeting September 9, 2009. Topics Covered. Background on the EDSP EDSTAC recommendations - PowerPoint PPT PresentationTRANSCRIPT
What Information Fulfills EDSP What Information Fulfills EDSP
Screening Requirements?Screening Requirements? Steve Levine, Ph.D.Steve Levine, Ph.D.
Science FellowScience FellowEcotoxicology & Risk AssessmentEcotoxicology & Risk Assessment
Monsanto CompanyMonsanto Company
ISRTP Meeting
September 9, 2009
2
Topics CoveredTopics Covered Background on the EDSPBackground on the EDSP
EDSTAC recommendationsEDSTAC recommendations
Functional equivalence and Other Scientifically Functional equivalence and Other Scientifically Relevant Information (OSRI)Relevant Information (OSRI)
International Regulatory Guideline StudiesInternational Regulatory Guideline Studies TOXTOX ECOTOXECOTOX
WoE approachesWoE approaches
3
The number of substances planned for Tier 1 The number of substances planned for Tier 1 screening is staggeringscreening is staggering
Pesticides Pesticides Commercial chemicals Commercial chemicals Cosmetic ingredients Cosmetic ingredients Food additives Food additives Nutritional supplements Nutritional supplements Certain mixturesCertain mixtures
Therefore, Therefore, screeningscreening must be efficient, robust, must be efficient, robust, and predictive at identifying potential EACsand predictive at identifying potential EACs
Tier 1 ScreeningTier 1 Screening
4
EDSTAC FrameworkEDSTAC Framework
Priority settingPriority setting Based on potential human exposureBased on potential human exposure
residues in food and drinking waterresidues in food and drinking water residentialresidential occupationaloccupational
Higher priority given to chemicals likely to have human Higher priority given to chemicals likely to have human exposure via multiple pathwaysexposure via multiple pathways
Tier 1 screeningTier 1 screening In vitroIn vitro and and in vivoin vivo assays assays Identify chemicals that can potentially interact with the Identify chemicals that can potentially interact with the
endocrine systemendocrine system
Tier 2 testingTier 2 testing Will establish the relationship between dose of an EAC and the Will establish the relationship between dose of an EAC and the
potential effects observed potential effects observed Assess risks humans and wildlifeAssess risks humans and wildlife
EDSTAC RecommendationsEDSTAC Recommendations
5
Recommended a minimal number of screens & tests to make sound decisions, thereby, reducing the time needed to make decisions
T1S screens should be MoA based to identify specific types of endocrine activity
Should be broadly predictive (sensitivity & specificity)
Should produce data that can be interpreted as either positive or negative (minimize Type I & II error rates)
Should be inexpensive and relatively quick and easy to perform
6
Tier 1 Screening BatteryTier 1 Screening Battery
In vitro Estrogen receptor binding
Estrogen receptor TA
Androgen receptor binding
Steroidogenesis (H295R)
Aromatase
In vivo Uterotrophic (rat)
Hershberger (rat)
Pubertal female (rat)
Pubertal male (rat)
Amphibian metamorphosis
Fish short-term reproduction
7
Alternative Means to MeetTier 1 Screening
EDSTAC recommended that it should be EDSTAC recommended that it should be permissible to meet T1S requirements by permissible to meet T1S requirements by submitting data that are “submitting data that are “functionally equivalentfunctionally equivalent” to ” to the data generated by the T1S batterythe data generated by the T1S battery
Functionally equivalent information could be Functionally equivalent information could be submitted for submitted for one or more one or more of the recommended of the recommended T1S assays or for the entire batteryT1S assays or for the entire battery
Pointed out that Pointed out that functionally equivalent functionally equivalent informationinformation exists for chemicals that have reproductive and exists for chemicals that have reproductive and developmental toxicity testingdevelopmental toxicity testing
Functional Equivalence & OSRIFunctional Equivalence & OSRI
8
Functional equivalence = data of a suitable nature and quality even if different methods were used i.e., provides the same essential predictive information as T1S
OSRI = information that informs the determination as to whether the substance may have a similar effect produced by a substance that interacts with EAT systems
OSRI may either be (1) functionally equivalent to information obtained from the Tier 1 assays or (2) data from assays that perform the same procedure / function as EDSP Tier 1 Screens
9
EPA’s Approach for Considering OSRI
Overview paper @ www.regulations.gov
Anyone may submit OSRI not just Test Order Recipients
Submitters should provide the information or cite previously submitted information
Information will receive different weights in a WoE - the quality of the information will weigh heavily
Factors will include sensitivity, specificity, confidence in the conclusions and applicability across taxa
Factors will also include route & duration/frequency of administration, dose levels, age at exposure, species, number of test units, variability, and whether the data provides a basis for conclusions for potential interaction with the endocrine system in mammalian and non-mammalian systems
OSRI for Tier 1 or Tier 2: metabolism, carcinogenicity, reproductive and developmental, and toxicogenomic
10
OSRI from OPPTS and OECD TestsOSRI from OPPTS and OECD Tests
TOXICOLOGYTOXICOLOGY Sub-chronic (OPPTS 870.3100)Sub-chronic (OPPTS 870.3100) Chronic (OPPTS 870.4100)Chronic (OPPTS 870.4100) Developmental/Teratology (OPPTS 870.3700)Developmental/Teratology (OPPTS 870.3700) 2-gen reproduction (OPPTS 870.3800)2-gen reproduction (OPPTS 870.3800)
ECOTOXICOLOGYECOTOXICOLOGY Avian reproduction Avian reproduction (OPPTS 850.2300)(OPPTS 850.2300) Chronic invert reproduction (OPPTS 850.1300/1350)Chronic invert reproduction (OPPTS 850.1300/1350) Early Life-stage (OPPTS 850.1400)Early Life-stage (OPPTS 850.1400) Fish full life-cycle Fish full life-cycle (OPPTS 850.1500)(OPPTS 850.1500)
OSRI Will IncludeOSRI Will Include
11
Toxicity tests following international regulatory guidelines Toxicity tests following international regulatory guidelines where full histopathology is carried out on:where full histopathology is carried out on: Endocrine tissues (pituitary, Endocrine tissues (pituitary, thyroidthyroid, parathyroid, pancreas , parathyroid, pancreas
adrenal, ovary and testis)adrenal, ovary and testis) Hormone sensitive male tissues (prostate, epididymides, Hormone sensitive male tissues (prostate, epididymides,
seminal vesicles)seminal vesicles) Hormone sensitive female tissues (mammary, uterus and Hormone sensitive female tissues (mammary, uterus and
reproductive tract)reproductive tract) And toxicity protocols that focus on reproduction, fertility And toxicity protocols that focus on reproduction, fertility
and development for mammalian species and other taxa and development for mammalian species and other taxa (birds, fish)(birds, fish)
These studies provide the strongest evidence of potential These studies provide the strongest evidence of potential endocrine effects and should be weighted above less endocrine effects and should be weighted above less comprehensive datacomprehensive data
12
Rat Multi-GenRat Multi-Gen
The 1996 USEPA guideline for a multiple generation The 1996 USEPA guideline for a multiple generation reproductive and developmental toxicity assay was reproductive and developmental toxicity assay was revised to include developmental benchmarks predictive revised to include developmental benchmarks predictive of ED potentialof ED potential
A diverse set of female endpoints (ovaries, uterus, A diverse set of female endpoints (ovaries, uterus, vagina, and mammary glands) vagina, and mammary glands)
Day of vaginal opening and first estrusDay of vaginal opening and first estrus Mating and fertility indicesMating and fertility indices
number of implantation sites, estrous cyclicitynumber of implantation sites, estrous cyclicity Male tissue weights and histopathology Male tissue weights and histopathology ((testes, testes,
epididymis, prostate, and seminal vesiclesepididymis, prostate, and seminal vesicles)) and other and other male parameters (sperm number and analyses)male parameters (sperm number and analyses)
13
Bridging OSRI to T1S AssaysBridging OSRI to T1S Assays
High High concordanceconcordance between the results of rat multi-gen and between the results of rat multi-gen and the rat Uterotrophic assaythe rat Uterotrophic assay
ConsistencyConsistency between MEDs for the Uterotrophic assay and between MEDs for the Uterotrophic assay and estrogen-related LOEL/LOAEL in estrogen-related LOEL/LOAEL in multi-generationmulti-generation testing testing
High High concordanceconcordance between the Uterotrophic assay and the between the Uterotrophic assay and the ER binding assay & the stably transfected TA for a large ER binding assay & the stably transfected TA for a large number of chemicalsnumber of chemicals
2-gen data should meet the requirement for the pubertal 2-gen data should meet the requirement for the pubertal assays: assays: Pubertal aPubertal assays largely have redundant endpoints with the ssays largely have redundant endpoints with the
2-gen study2-gen study
14
Avian reproduction studiesAvian reproduction studies Gold standard or highest tier of avian testingGold standard or highest tier of avian testing Bobwhite quail and mallard duckBobwhite quail and mallard duck Studies do not include exposure during all relevant stages of Studies do not include exposure during all relevant stages of
development or organ histopathologydevelopment or organ histopathology However, provides valuable information in a WoE context to assess However, provides valuable information in a WoE context to assess
potential effects of endocrine active substancespotential effects of endocrine active substances Sensitivity of 1-gen vs 2-gen Japanese quail?Sensitivity of 1-gen vs 2-gen Japanese quail?
Reproduction study designReproduction study design Dietary exposure for ~10 weeks prior egg-layingDietary exposure for ~10 weeks prior egg-laying Photoperiod change initiates egg-laying Photoperiod change initiates egg-laying Exposure continues for ≥8 weeks Exposure continues for ≥8 weeks Endpoints: eggs laid, eggs damaged, eggs set, egg shell thickness, Endpoints: eggs laid, eggs damaged, eggs set, egg shell thickness,
viable embryos, live embryos, hatchlings, 14-day survivors, eggs viable embryos, live embryos, hatchlings, 14-day survivors, eggs laid/female, eggs laid/female/day, 14-day survivors/femalelaid/female, eggs laid/female/day, 14-day survivors/female
OSRI to T1S Assays - ECOTOXOSRI to T1S Assays - ECOTOX
15
Fish full life cycle (FFLC) studyFish full life cycle (FFLC) study Gold standard for aquatic vertebrate ecotox testingGold standard for aquatic vertebrate ecotox testing Entire LC is exposed = most sensitive life-stage is testedEntire LC is exposed = most sensitive life-stage is tested ~260 to 300 days for FTHD minnows = T1S spp.~260 to 300 days for FTHD minnows = T1S spp.
FFLC study designFFLC study design ELS → growth & repro → ELSELS → growth & repro → ELS First gen: hatching success, time-to-hatch, survival, growth First gen: hatching success, time-to-hatch, survival, growth
and development, reproductive success (# of spawns, # of and development, reproductive success (# of spawns, # of eggs)eggs)
Second-gen: time-to-hatch, survival, growth and Second-gen: time-to-hatch, survival, growth and developmentdevelopment
OSRI to T1S Assays - ECOTOXOSRI to T1S Assays - ECOTOX
16
Principles for Evaluating Data in a WoEPrinciples for Evaluating Data in a WoE..
Consistent pattern of responses for a MoA (+ or -)Consistent pattern of responses for a MoA (+ or -)
The nature and range of the biological effects observedThe nature and range of the biological effects observed
The shape of DRCs curves when availableThe shape of DRCs curves when available
The severity and magnitude of the effectsThe severity and magnitude of the effects
Interpretation made in the context of biological significance & Interpretation made in the context of biological significance & biological plausibilitybiological plausibility
The presence or absence of responses in multiple taxaThe presence or absence of responses in multiple taxa
Evaluate results in the context of natural variability using control data Evaluate results in the context of natural variability using control data (historical and concurrent) (historical and concurrent)
17
Principles for Evaluating Data in a WoEPrinciples for Evaluating Data in a WoE
Results from apical assays (MTD dose) need to be Results from apical assays (MTD dose) need to be weighted appropriately when accompanied by decreases in weighted appropriately when accompanied by decreases in BW or other potential confoundersBW or other potential confounders
In vivoIn vivo results generally are considered to have more results generally are considered to have more weight than weight than in vitroin vitro results results
AvailableAvailable in vitro in vitro assays should not be used as yes/no assays should not be used as yes/no determinants to proceed to Tier 2 (ER binding example)determinants to proceed to Tier 2 (ER binding example)
SARs = critical step in the WoE processSARs = critical step in the WoE process
A WoE approach for OSRI must be developed along with A WoE approach for OSRI must be developed along with the WoE framework for the T1Sthe WoE framework for the T1S
18
Closing ThoughtsClosing Thoughts
SARs are OSRI and weighted appropriatelySARs are OSRI and weighted appropriately
There will be instances where OSRI will meet all There will be instances where OSRI will meet all or some of the T1S requirements, particularly for or some of the T1S requirements, particularly for food use pesticides.food use pesticides.
Development of a transparent WoE approach is Development of a transparent WoE approach is desperately needed not only in the interpretation desperately needed not only in the interpretation of OSRI but for the T1S data before testing is of OSRI but for the T1S data before testing is required.required.