Post on 16-Dec-2015
June 2010 LANDSIEDEL 1
Chemical Industries Role in Tomorrows Toxicity Testing
Robert Landsiedel, Susanne Kolle, Tzutzuy Ramirez, Hennicke Kamp and Ben van Ravenzwaay
The Future of Chemical Toxicity Testing in the United States and Beyond
June 21st 2010
National Press Club, Washington DC Holeman Lounge, 13th Floor
Endocrine
Disruption
fog
Organ Toxicity
sand bar
Genotoxicity
fog
Developmental
Toxicity
shoal
Neurotoxicit
y sand bar
June 2010 LANDSIEDEL 3
Animal Welfare
TestingAcceptance
Validity
Time
Coststest substance
use
Producer’sResponsibility
REACH
CosmeticsDirective
C&L
non-EUlegislation
Alternative Methods Optimizing Toxicity Testing
June 2010 LANDSIEDEL 4
Acute Oral ToxicityCytotoxicity vs. Rat Acute Oral Toxicity
Assay:
Balb/c 3T3 mouse cell line
Viability assay using Neutral Red Uptake
Prediction model based on correlation of acute oral rat LD50 and cytotoxicity IC50
Data set:
203 pairs of cytotoxicity data and acute oral data (screening or OECD 423)
agrochemical active ingredients, agrochemical formulations, chemicals
June 2010 LANDSIEDEL 5
300 - 2000 mg/kg(cat. 4)
Acute Oral ToxicityCytotoxicity vs. Rat Acute Oral Toxicity
LD50 (acute oral rat) vs. EC50 Balb/c NRU, interpol. LD50
50300
2000
LD50 (GHS classification)
EC
50 I
nte
rpo
l. L
D5
0 [
mg
/kg
]
> 2000 mg/kg (cat. 5)
> 50 - 300 mg/kg(cat. 3)
≤ 50 mg/kg(cat. 2)
Overall concordance: 35 %Periodically assess the performance of methodsin routine testing.
June 2010 LANDSIEDEL 6
CPRG
CPRyeast ß-gal
ß-gal
estrogenic activity antiestrogenic activity
Yeast Estrogen/ Androgen Screening Assays (YES/YAS)
Recombinant yeast strains (human receptors and reporter gene)
Agonistic and antagonistic effects measureable
Determination of effect by reporter assay
Incubation of yeast cells with test substances
Measurement of hormonal activity and cytotoxicity
Reproductive Toxicity Endocrine Disruption
June 2010 LANDSIEDEL 7
YES/YASnegative
further development
positive
alternative structures
positivefurther development, but
develop alternative structures
focus in vivo testing
extended 28 day study Hershberger assay Uterotrophic assay early Reprotox testing
Reproductive ToxicityScreening Strategy
negative
June 2010 LANDSIEDEL 8
Mode of ActionMetabolomics
Test substance 28 day Rat studies Metabolite profile in
plasma
MetaMap®TOX
identification of relevant metabolites correlation analysis against
reference profiles comparison against specific patterns
for toxicity
Identification of target organs modes of action substance classes
June 2010 LANDSIEDEL 9
Three patterns of liver effects:rats (females left and males right) treated with liver enzyme inducers, liver toxic compounds and peroxisome proliferatorsrelative to untreated controls
Metabolomics MoA Identification
June 2010 LANDSIEDEL 10
Metabolomics Example: 2- and 4-Acetylaminofluorene
2-Acetylaminofluorene
- strong liver enzyme inducer- liver carcinogen
- immune suppressant- bladder carcinogen
4-Acetylaminofluorene
- slight liver enzyme inducer- no liver carcinogen
- lipid accumulation in liver- immune suppressant
NH
ONH
O
June 2010 LANDSIEDEL 11
Metabolite profile compared to other liver enzyme inducers2-AAF 4-AAF
Metabolomics Example: 2- and 4-Acetylaminofluorene
Extract more informationfrom (regulatory) studies,
to provide a sound scientific basis for grouping and read across of chemicals:
from QSAR to QBAR
June 2010 LANDSIEDEL 12
Acute dermal toxicity:
Total number of selective (relevant) classificationsbased on LD50 dermal in ECB data base: < 1%
Mouse cancer bioassay:
The mouse does not add significantly to conclusionson cancer risk assessment (compared to rat study)
90 day and 12 month dog studies:
LOEL in 90 day dog is lower than that in rats for ~50% of compounds
LOEL in 90 day dog study is more than 3-fold compared to 12 month study for about 90% of compounds
Redundancy in Animal Testing of Chemicals
HESI ACSA Task Force
June 2010 LANDSIEDEL 13
New paradigmCurrent paradigmAnimals
7681272Total
4872Dogs
0520Mice
720680Rats
Potential reduction in Animal Testing for Systemic Toxicity
HESI ACSA Task Force
Periodically assess the regulatory impact of studies,
and delete those that are not used.