The Toxicologist - Society of Toxicology

vitro with this potentially insect-selective pesticide showed that exposure to 6 micromolar
concentrations for 1 hr caused 99% inhibition of the AChE in greenbug
aphids (shizaphus graminum) but less than 2% inhibition of the human RBC
AChE. Although AMTS18 is not yet potent enough for field use we decided to determine
whether methanethio-sulfonates in general should be expected to exhibit
unacceptable non-specific toxicity in mammals. For the purpose of this acute toxicity
study, male ICR CD1 mice were gavaged with a dose of 33mg/kg, 100mg/kg or
300mg/kg AMTS18 in corn oil and, 3 hr later, blood samples were collected to test
plasma AChE activity. At the same point a functional observational battery test
(FOB) was carried out to evaluate neurological and behavioral effects. Exactly 24hr
later, the FOB test was repeated, and terminal blood samples were collected for assays
designed to detect toxicity in liver (alanine aminotransferase, alkaline phosphatase,
and gamma-glutamyl transpeptidase, kidney (plasma urea nitrogen or
BUN and creatinine), and heart (creatine kinase-MB). Plasma levels of glutathione
(known to react with methanethiosulfonates) and AChE activities were also assayed.
The results of this study showed no mortality any of AMTS18 groups, hence
LD50 could not be determined, and none of the sentinel markers exhibited statistically
significant changes (as evaluated by one way analysis of variance). Our FOB
studies likewise failed to show any significant effects. On the basis of these findings
AMTS18 exerts no detectable toxicity even at the high dose of 300mg/kg delivered
by the gavage route. We conclude that it is worth exploring equally selective but
more potent methanethiosulfonates as insect-targeting pesticides with reduced risk
to mammals.
1550 SKIN BIOCOMPATIBILITY TESTING OF A
POLYISOPRENE ELASTOMER.
N. Pechacek, T. Brunshidle and L. Eichinger. 3M, St. Paul, MN.
Elastomer materials (elastomers) have numerous commercial applications due to
their extensibility, stretchability, and durability. Sources of these materials can be
natural, synthetic, or a hybrid of natural and synthetic. Elastomers frequently have
applications that involve significant skin contact. Historical use experience by industry
has shown that various elastomers can pose notable skin hazards (e.g., allergic
contact dermatitis, primary and/or cumulative skin irritation). Subsequently,
uses of elastomers in products that result in significant skin contact necessitate a
thorough assessment of their skin biocompatibility prior to commercialization. To
conduct such an assessment, ISO Standard 10993, Biological Evaluation of
Medical Devices, Part I for surface devices with skin contact; served as guidance for
evaluating a polyisoprene elastomer proposed for use in a 3M product with significant
skin contact. The skin biocompatibility assessment consisted of three assays:
an in-vitro cytotoxicity: L929 agar overlay test (cytotoxicity assay); an acute dermal
irritation test in rabbits (dermal irritation assay); and a local lymph node assay in
mice (LLNA). The cytotoxicity assay provided an assessment of the potential cytotoxicity
of leachable materials from the elastomer. The dermal irritation assay was
an in vivo primary dermal irritation assay modified to incorporate repeat skin contact
for 7 hours/day for 5 consecutive days to assess both primary and cumulative
irritation of the neat elastomer. Lastly, the LLNA was conducted to provide an evaluation
of the dermal sensitization potential of extractables from the elastomer.
Under the study conditions, no appreciable cytotoxicity, irritation, or sensitization
was observed. Subsequently, it is concluded that the polyisoprene elastomer is unlikely
to have appreciable skin hazards.
1551 CONSIDERATIONS FOR DEMONSTRATING THE
INTER-LABORATORY RELIABILITY OF
CHORIOALLANTOIC MEMBRANE VASCULAR ASSAY
(CAMVA) AND THE BOVINE CORNEAL OPACITY AND
PERMEABILITY ASSAY (BCOP).
G. Mun 2 , N. Wilt 2 , D. A. Donahue 1 , J. Avalos 1 , K. Norman 2 , A. Hilberer 2 , F.
A. Simion 1 and H. Raabe 2 . 1 Research and Development, Kao Brands Company,
Cincinnati, OH and 2 Institute for in vitro Sciences, Inc., Gaithersburg, MD.
In vitro assays evaluating ocular irritation potential are routinely used by personal
care companies. Two of these in vitro assays are the Chorioallantoic Membrane
Vascular Assay (CAMVA) and the Bovine Corneal Opacity and Permeability Assay
(BCOP). These assays do not require the use of live animals, provide reliable predictive
data and are rapid to conduct. The BCOP uses excised bovine corneas to
predict ocular irritation. The CAMVA uses vascular network of fertilized chicken
eggs as a conjunctival model to predict ocular irritation. Both BCOP and CAMVA
have been used for over fifteen years for product development, workplace safety,
and safety claims substantiation. This poster describes procedures and considerations
for demonstrating the inter-laboratory reliability of the BCOP and CAMVA.
For Kao Brands Company, a large BCOP and CAMVA historical database exists
that covers multiple consumer product categories such as hair shampoos, skin
cleansers, and hair styling sprays (containing ethanol). Therefore, a proper audit of
candidate contract laboratories is important for seamlessly generating consistent results.
First, candidate contract laboratories were audited for technical capabilities
and GLP compliance. Next, reference materials with known BCOP and CAMVA
data were tested at each new laboratory for verification of proper assay performance.
After qualifying a contract laboratory, assay data generated from additional
samples have been examined (results should be within the historical ranges of similar
products) for additional assurance. The consistency of new data indicates that a
detailed qualification process of new contract laboratories is important in generating
accurate data and maintaining a high quality database.
1552 SAFETY EVALUATION OF β-HYDROXY
CYCLODEXTRIN IN WISTAR RATS.
R. Nirogi, V. Goyal, R. Vedamurthy, M. A. Mulla, S. Pandey, S. Jana and A.
Gothi. Toxicology, Suven Life Sciences Limited, Hyderabad, Andhra Pradesh, India.
Sponsor: V. Reddy.
n preclinical safety assessment of potential new drugs, it is required that the material
of interest must be suitably formulated in a manner that allow adequate administration
of the test substance with little or no effects in test animals that is attributable
to the vehicles used in preparing such formulations. There are many vehicles
that have been used in preclinical formulation. Β-Hydroxy Cyclodextrin (BCD) is
one of the most commonly used vehicles to solubilize and stabilize the test substance
for formulation preparation in preclinical studies. The present study was
planned to evaluate the oral toxicity of BCD in Wistar rats. Three groups of Wistar
rats (4/sex/group) were dosed orally at 500, 2000 and 4000 mg/kg/day of BCD and
one control group was dosed with distilled water for 14 consecutive days. No treatment-related
clinical signs were noticed up to 4000 mg/kg although loose feces
were observed during fasting before terminal sacrifice on day 15 at 2000 and 4000
mg/kg/day. Body weight and feed consumption were slightly decreased in male rats
at 2000 and 4000 mg/kg/day but these changes did not reach statistical significance.
No changes were observed in any hematological, biochemical or urine parameters
after 14 days of treatment except minimal increase in ALP level in female
rats at 2000 and 4000 mg/kg. No abnormalities were found at necropsy that could
be attributed to the treatment. On microscopic examination, no treatment-related
alterations were observed in examined organs and tissues. In conclusion, transient
diarrhea and slight reduction in body weight and feed consumption were the only
treatment-related effects. These changes are well-known physiological responses to
the presence of high amounts of non-digested, fermentable carbohydrates in the
lower gut. Based on these results, it is inferred that BCD can be administered up to
4000 mg/kg/day without any apparent effect on health of animals.
1553 ICCVAM RECOMMENDATIONS ON THE USEFULNESS
AND LIMITATIONS OF THE CYTOSENSOR
MICROPHYSIOMETER® (CM) TEST METHOD FOR
OCULAR SAFETY TESTING.
J. Merrill 1 , D. Lowther 1 , A. Layton 2 , J. Redden 3 , M. Wind 4 and W. Stokes 5 .
1 U.S. FDA, Silver Spring, MD, 2 U.S. CPSC, Bethesda, MD, 3 U.S. EPA,
Washington, DC, 4 U.S. CPSC (Retired), Bethesda, MD and 5 NICEATM, NIEHS,
Research Triangle Park, NC .
ICCVAM recently evaluated several in vitro test methods as potential replacements
for the rabbit eye test for identifying potential ocular hazards. None of the methods
were considered adequate as complete replacements. However, ICCVAM concluded
that test substances within a defined limited applicability domain (water soluble
surfactants, surfactant-containing formulations and nonsurfactants) that are
positive for severe effects in the CM can be classified as ocular corrosives/severe irritants
(EPA Category I, EU R41, GHS Category 1). False positive rates ranged from
0% (0/17, 0/18) to 10% (3/29) and false negative rates from 9% (2/23) to 50%
(6/12) depending on the hazard classification system used. ICCVAM also concluded
that test substances within an even more restricted applicability domain
(water soluble surfactant chemicals and certain types of surfactant-containing formulations)
can be considered as not classified for ocular hazards (EPA Category IV,
EU Not Labeled, FHSA Not Labeled) without any further testing if they are negative
in the CM. Although false positive rates were high (50% [3/6] to 69%
[18/26]), false negative rates ranged from 0% (0/27, 0/28, or 0/40) to 2% (1/42 or
1/47) depending on the hazard classification system used. A chemical that produces
a response in CM between these two extremes would require additional testing (in
vitro and/or in vivo) to establish a definitive classification. The CM test method is
not considered adequately valid for identification of mild or moderate ocular irritants
(GHS Categories 2A/2B; EU R36; EPA Categories II/III). ICCVAM also recommended
a standardized CM protocol and future studies to expand the applicability
domain of the CM. These recommendations have been forwarded to Federal
agencies and if accepted, the CM will be the first in vitro test method available in
the U.S. for identifying substances that do not require ocular hazard labeling.
SOT 2011 ANNUAL MEETING 333