United States
Environmental Protection
Agency
Health Effects Research
Laboratory „
Research Triangle Park NC 27711 ''x
Research and Development
EPA-600/S2-82-010 August 1982
Project Summary
Comparison of Ames
Salmonella typhimurium Plate
Incorporation Test Protocols
Stephanie Toney and Larry D. Claxton
This document is a companion
volume to the Compilation of Ames
Salmonella typhimurium Plate Incor-
poration Test Protocols. Its purpose is
to tabulate the differences between
the submitted protocols and to note the
modifications from the 1975 Ames
reference. The tables show the differ-
ences obtained between laboratories
in bacterial strain maintenance, meta-
bolic activation systems, chemical
controls, preparation of media and
solutions, and of the assay procedure
itself. The recommendations of de
Serres and Shelby and any revisions
by Ames are also included.
No attempt is made to evaluate any
laboratory or indicate a preferable
method for the test. Some laboratories
may have Standard Operating Proce-
dures (SOPs) that are more detailed
than the submitted protocols. Changes
or revisions that have taken place in a
protocol since submission are not
noted in this document. In addition,
laboratories that use Ames' reference
(1975) as their main protocol may
have only sent their modifications.
This Project Summary was devel-
oped by EPA's Health Effects Research
Laboratory, Research Triangle Park,
NC, to announce key findings of the
research project that is fully docu-
ed in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
In 1975, Ames et al., published a
detailed protocol that incorporated the
use of a mammalian metabolizing
system, thereby establishing the Ames
test as a routine screening system for
mutagenicity and potential carcinogeni-
city. Since then, many laboratories have
introduced a variety of changes and/or
additions.
The U.S. Environmental Protection
Agency (EPA) therefore decided to
conduct an informal survey of laboratories
that utilize the Ames test. A list of
laboratories routinely performing the
test was obtained from Dr. Mike Shelby
at the National Institute of Environmental
Health Sciences, Research Triangle
Park, NC. An initial letter was sent to the
46 laboratories, 33 of which responded.
These included six laboratories that no
longer performed the Ames test, one
laboratory that had closed and 25
laboratories that submitted protocols.
The other responding laboratory elected
to restrict usage of their protocol. A list
of names and addresses of participating
laboratories is found in Table 1. This
publication is a tabulated qualitative
summary and comparison of the submit-
ted protocols.
Bacterial Strains
Bacterial Strains Routinely
Used
The Ames reference (1975) suggested
using three standard strains for routine
testing (TA1535, TA1537, and TA1538)
to be used in combination with the
newer derivative strains (TA98.TA100).
The majority of the participating labor-
atories use all five tester strains
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Table 1. Names and Addresses of Participating Laboratories
Dr. Andrew Sivak
Arthur D. Little. Inc.
25 Acorn Park
Cambridge, MA 02140
Mr. James P. Crow/ey
Battelle Columbus Laboratories
505 King Avenue
Columbus, OH 43201
Dr. Douglas M. Hanson
Bioassay Systems Corporation
100 Inman Street
Cambridge, MA 02139
Mr. Clyde R. Goodheart
Biolabs, Inc.
2910 MacArthur Blvd.
Northbrook, IL 60062
Dr. Rae E. Drazin
Bio- Technics Laboratories, Inc.
1133 Crenshaw Boulevard
Los Angeles, CA 90019
Dr. William T. Speck
Case Western Reserve University
Department of Pediatrics
2103 Adalbert Road
Cleveland, OH 44106
Dr. Steve Ha worth
EG&G Mason Research Institute
1530 E. Jefferson Street
Rockville, MD 20852
Dr. Larry Claxton
Genetic Toxicology Division
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Dr. Vincent F. Simmon
Genex Corporation
6110 Executive Blvd.
Suite 1090
Rockville, MD 20852
Ms. Nancy E. McCarroll
Hazleton Laboratories America, Inc.
9200 Leesburg Turnpike
Vienna. VA 22ISO
Dr. George C. Lavelle
Hill Top Research, Inc.
Department of Toxicology
Miamiville, OH 45147
Mr. Peter W. Barbara
IIT Research Institute
Life Sciences Division
10 West 35th Street
Chicago, IL 60616
Ms. Shirley Louie
Jefferson Professional Services
P.O. Box 3397
Little Rock, AR 72203
Dr. Andrew M. Tometsko
Litron Laboratories. Ltd.
1351 Mt. Hope Avenue
Rochester, NY 14620
Dr. David Brusick
Litton Bionetics, Inc.
5516 Nicholson Lane
Kensington, MD 20795
Dr. Carol Richardson
Meloy Laboratories, Inc.
6715 Electronic Drive
Springfield, VA 22151
Mr. Andrew M. Losinkoff
Microbiological Associates
5221 River Road
Bethesda, MD 20016
Ms. JoAnne Gridley
Monsanto Research Corp.
1515 Nicholas Road
Dayton Laboratory
Dayton. OH 45407
Dr. John E. Preston
USEPA-NEIC
Bldg. 53
Box 25227
Denver, CO 80225
Dr. Bruce C. Casto
Northrop Services, Inc.
P.O. Box 12313
Research Triangle Park, NC 27709
Dr. Robert A. Finch
Raltech Scientific Services
A Division of Ralston Purina Co.
P.O. Box 7545
Madison, Wl 53707
Mr. Thomas J. Hughes
Research Triangle Institute
Box 12194
Research Triangle Park, NC 27709
Dr. Nathan Greene
Southwest Foundation for Res. & Ed.
P.O. Box 23147
San Antonio. TX 78284
Dr. David C.L Jones
SRI International
333 Ravenswood Avenue
/We/7/o Park, CA 94025
Ms. Melanie Baltezore
UNILAB Research
2800 7th Street
Berkeley, CA 94710
routinely. Two of the laboratories do n<
use TA1538 routinely. One uses onl
three strains: TA98, TA100, and TA153
Another does not say what strains
uses. One laboratory appears to subst
tute TA1575 for TA1535.
Storage of Strains
Ames is now employing master plate
for the temporary storage of strains. Hi
laboratory stores master plates in a coli
room, where all culturing is performed
The master plates are kept for one to twi
months. Their preparation involve!
making minimal glucose agar anc
spreading histidine and biotin. Ampicillir
is also spread on plates used for strain:
TA98 and TA100. The plates sit for one
or two days to allow the compounds tc
diffuse into the media. The six labora
tories that list a procedure report usinj
the same procedure as Ames. Perma-
nent storage is in a 2 ml sterile glass via
with rubber-lined screw tops. The
culture is stored at a concentration ol
0.8 ml of a 16-h nutrient broth culture tc
0.07 ml DMSO. It is kept at -80°C in a
Revco freezer. The laboratories that list
a procedure agree with the Ames
permanent test and revised temporary
storage procedures.
Histidine Requirement Test
Ames' recommendations for the
histidine requirement test specify
minimal media petri plates. The Salmo-
nella is streaked onto the plate, an
aliquot of 0.1 ml of a 0.1 M solution of L-
histidine is then spread. Biotin is also
used with strains that have the uvrB
deletion. An aliquot of 0.1 ml of a 0.5
mM solution is spread onto the plates.
Plates without histidine are used as a
negative control. Nine laboratories do
not mention the methods they employ to
monitor this requirement. Of the ones
who mentioned a procedure, five
laboratories say that they check this
requirement but give no description.
Nine laboratories repeat the Ames
procedure in their protocol. Two others
use an overlay rather than streak the
bacteria on the plate.
Determination of rfa
Character
Ames uses nutrient agar plates and a
16-h incubation of 10s concentration
Salmonella in nutrient broth culture. A
total of 0.1 ml of the tester strain is
added to an agar overlay and poured
on the nutrient agar plate. Ames gives
two possibilities for a sensitivity test
compound: an aliquot of 10/ulofa 1 mg/
ml solution of crystal violet or 2 mg
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sodium deoxycholate. The test com-
pound is applied to a sterile filter paper
disc which is then placed on the petri
plate. The plate is incubated for 12 h at
37°C and then interpreted. If the
mutation is still present there will be a
zone of inhibition around the disc. The
size of the zone is approximately 14 mm
for crystal violet and 13 mm for
deoxycholate. Six laboratories do not list
a method of determination, and four
mention that they do the procedure. Of
the remaining laboratories, nine repeat
Ames' procedure, and two use minimal
agar rather than nutrient agar. One
laboratory mentions the compound and
adds that it checks for this requirement.
One laboratory streaks the Salmonella
rather than using an overlay. Two
others use Mueller-Hinton plates in
combination with a swab-streak of
Salmonella.
Ampicillin Resistance
Ames (1975) recommends using nu-
trient agar plates for the ampicillin
resistance test. A total of 10 /ul of an 8
mg/ml ampicillin solution in 0.02 N
NaOH is streaked on the plate and
cross-streaked with Salmonella. After
12-24 h of incubation at 37°C, the
plates are evaluated. If the mutation is
present (TA98, TA100) there should be
no zone of inhibition around the streak.
De Serres and Shelby recommended
that the ampicillin be put on the plate in
a disc form and used in combination
with a top-agar overlay. Six laboratories
do not list a procedure. Six others say
they perform this test but give no in-
structions. Three follow the procedure
given in Ames, 1975. Four laboratories
follow the recommendation of de Serres
and Shelby. Two use a Mueller-Hinton
plate with an Ampicillin disc and a
swab-streak of Salmonella. Three
others spread the ampicillin over the
entire plate and score the mutation as
present with growth on the plate. One
laboratory does not check for this muta-
tion.
uvrB Deletion
Ames uses nutrient broth agar with a
streak of Salmonella for this test. Half
the plate is irradiated with a UV light for
6 seconds (8 seconds for TA98, TA100)
at a distance of 33 cm (i.e., plate to lamp
distance). The plate is then incubated
for 12-24 h at 37°C and scored. If the
mutation is present, no growth will
occur on the exposed side. Eight
laboratories perform this test as de-
scribed. Eight do not list a procedure.
and four say they perform the test. One
differs from Ames only in the use of
Mueller-Hinton plates. Two laboratories
use an overlay rather than a streak for
the Salmonella and also employ different
time intervals. One laboratory irradiates
sections of the plate from 10 sec to one
minute, and incubates for 48 h. One
laboratory does not list a procedure but
says it uses Ames' identically.
Compound Sensitivity
Verification
Ames recommends comparing TA98
and TA100 to its parent strains in a
standard assay with Aflatoxin 61 and
methyl methanesulfonate to show
increased mutagenesis by TA98 or
TA100. Only one laboratory mentions
this procedure.
Spontaneous Reversion Rate
Ames suggests that the spontaneous
reversion rate be checked in a standard
assay; an acceptable interpretation is
that plate counts fall within the standard
individual labortory's limits. Five labora-
tories check the reversion rate but give
no details. Eleven others follow the
Ames suggestion, and nine do not
mention the procedure.
Metabolic Activation System
Preparation of S-9 Fraction:
I. Induction of Animal
Ames uses the PCB mixture Aroclor
1254 for inducing male rats weighing
approximately 200 g, and suggested
using the Spraque-Dawley/Biol strain.
The method of induction is a single
intraperitoneal injection five days
before sacrificing the animal. The
dosage is 500 mg of Aroclor per kg of
body weight, and the concentration is
200 mg/ml suspended in corn oil. Food
and water are given adlibitrium until 12
h before sacrifice, at which time the
food is removed. Three laboratories do
not describe their induction method.
Five laboratories restrict their discus-
sion to the strain of rat and/or the
induction chemical used. Nine others
use essentially the same procedure
described by Ames. One laboratory
differs from Ames only in the strain of
rat used. Five laboratories differ from
Ames in the time rats are deprived of
food — 24 h rather than 12. One labora-
tory sacrifices the rats by gassing COz.
One laboratory uses Aroclor 1242
rather 1254 as an alternative to corn oil;
sesame oil is mentioned by one labora-
tory.
Preparation of S-9 Fraction:
II. Preparation of Fraction
Ames gives a detailed procedure for
the fraction preparation after sacrifice
of the rat. All work is done between 0
and 4°C using sterile materials and
solutions. The liver is removed and
washed twice with cold 0.15 M KCI. It is
then minced with sterile scissors and
homogenized using a Potter-Elvehjen
homogenizer with a Teflon pestle. After
homogenizing, a Sorvall RC2-B centri-
fuge with a SS-34 head is used for 10
min at 8700 rev/min (9000xg). The
decanted supernatant fraction is stored
in a 2 ml plastic liquid nitrogen storage
tube. It is quick-frozen on dry ice and
stored in a Revco freezer at -80°C. Five
laboratories make no mention of the
procedure. Five others list only the
centrifuge speed or organ used or
storage temperature. Eight laboratories
give essentially the same procedure as
the one described by Ames. Three
laboratories differ only in the amount of
fraction in a storage container. One
expands the Ames protocol to include a
detailed homogenizing procedure. One
laboratory used a Polytron J21C centri-
fuge instead of a Sorvall. Two use a
sucrose wash in combination with two
KCI washes. One laboratory that uses a
sucrose wash also centrifuges for 25
min rather than 10.
Preparation of S-9 Mix
Ames lists the following ingredients
and amounts for the S-9 mix:
S-9 - 0.04-0.1 ml/ml mix
MgCb - 8 ^mole/ml mix
KCI - 33 //mole/ml mix
G-6-P - 5 ^mole/ml mix
NADP- 4//mole/ml mix
sodium phosphate buffer - 100 ^mole/ml mix
He recommends keeping the mix on ice
for the assay procedure and only
retaining it for several hours. Most
laboratories use the quantities listed
above. One laboratory does not list
quantities. The only significant differ-
ence is that one laboratory I isted the use
of 100 //mole G-6-P/ml mix, 5 /umule
NADP/ml mix, and 4 jumole sodium
phosphate buffer/ml mix. One laboratory
omits KCI as a component in the mix.
Stock Solutions
Sodium Phosphate Buffer
Ames recommends using a 0.2 M
sodium phosphate buffer in the S-9 mix.
-------
The pH of the buffer is 7.4 and the
amount used per ml of mix is 100/umole.
One laboratory does not say what buffer
it uses, and two list the pH. Five
laboratories list the pH and amount of
buffer used. Two others list the pH and
the molarity as described by Ames.
Eight laboratories give essentially the
same description as Ames, and four
use different buffer molarities (0.125,
0.4, 0.1 or 1 M). The laboratory using 1
M buffer uses 0.1 ml buffer/ml mix.
One other uses an NADPH generating
system. One laboratory uses a mixture
of monobasic and dibasic sodium
phosphate.
Microsomal Salt Solution
Ames says that the microsomal salt
solution should consist of 0.4 M MgCI2
and 1.65 M KCI. The quantities per ml of
mix are 8 //mole MgClz and 33 //mole
KCI.
Twenty laboratories list the same
quantities and/or molarity as Ames.
One laboratory does not give any
• information for the microsomal salt
solution. One laboratory gives the
molarity as 0.4 M for both MgCI2 and
KCI. One laboratory reports 0.65 M
concentration for KCI. Another reports
standard molarities but gives gram
weights 10x higher than expected. One
laboratory uses an NADPH generating
system.
Glucose Stock Solution
Ames lists no directions for the
preparation of a glucose stock solution.
Five of the laboratories make no
mention of a glucose stock solution.
Sixteen laboratories say they use a 2%
solution. One laboratory uses a 0.8%
solution and two use a 1% solution. One
uses a stock solution of 20% but does
not give the quantity of this solution that
is used in the agar.
Histidine/Biotin Stock
Solution
Ames reports a molarity of 0.5 mM for
both the histidine and the biotin in the
His/Bio stock solution or quantities of
8.7136 mg/l histidine and 11.1045 g/l
biotin. He recommended using 10 ml of
the solution per 100 ml top agar.
Fourteen of the laboratories use these
amounts. Two do not give instructions
for this solution. One laboratory reports
using trace amounts of His/Bio. Four
use 0.05 mM solutions. One laboratory
uses 39 mg/l of histidine. One laboratory
uses 10 /ug/ml of histidine and 12
//g/ml of biotin in their stock solution.
One laboratory uses 0.0976 g biotin/l
and 0.0525 g histidine/l in the solution.
Another uses 61.0 mg biotin/500 ml
and 48.0 mg histidine/500 ml and 100
ml of the stock solution per liter of top
agar.
VBME Salt Solution
Ames does not give instructions for
the preparation of the VBME solution.
Vogel's reference gives the following
gram amounts per liter of solution:
MgS04-7H20 - 10g
Citric Acid • HaO - 100g
KZHP04-Anhydrous -500g
NaNH4-HP04-4H20 -175g
H20 -670ml
The pH is 7.0 and the solution is a 50x
concentration. Fourteen of the labora-
tories use these same instructions and
10 give none. One laboratory gives the
same gram amounts but lists the
concentration of the solutions at 25x.
Media
Top Agar Overlays
Ames recommends a solution of 0.6%
Difco agar and 0.5% NaCI for top agar.
Before using, the top agar is melted in a
steam bath and 10 ml of a His/Bio
solution is added to 100 ml of top agar.
The His/Bio solution consists of a 0.5
mM concentration of histidine and a 0.5
mM concentration of biotin. Aliquots of
2 ml are pipetted into culture tubes and
kept warm until use. Nine laboratories
prepare overlays by this procedure. Nine
others give the quantities of the
ingredients or the His/Bio concentration
but do not elaborate further. One
laboratory does not list information on
the overlays. Three use media other
than Difco, and three use concentrations
different from those recommended by
Ames.
Petri Plate Agar
Ames specifies Falcon plastic 100 x
15 mm petri plates, and 30 ml of a 1.5%
Bacto-Difco agar with 2% glucose and
VBME salt solution for the bottom agar.
Two laboratories do not discuss their
petri plate agar. For most, the amount of
agar in a plate ranges from 20 to 30 ml.
Three laboratories prefer nonethylene
oxide sterilized plates. Two laboratories
do not use Difco agar. Thirteen labora-
tories follow the recommendations of
Ames. One laboratory uses 16 g/l of
agar. Four laboratories do not indicate
the agar concentration.
Nutrient Broth
Ames originally used Difco Nutrien
Broth but has since recommendei
Oxoid #2 broth. Seven laboratories sa
they use Oxoid #2. Five laboratories usi
Difco; one uses Columbia Broth, am
one recommends Lab-Lemcopowder an<
peptone. The 11 remaining laboratories
do not indicate the type of broth used ii
this laboratory.
Chemical Controls
Control Mutagens/
Carcinogens Routinely Used
For activation assays Ames recom-
mends using 2-aminoflourene, aflatoxin
Bi, and benzo(a)pyrene. De Serres and
Shelby recommend using 2-aminoan-
thracene solely. Fourteen laboratories
use 2-aminoanthracene exclusively.
Two laboratories use 2-aminofluorene
exclusively. Two others use 2-amino-
anthracene and benzo(a)pyrene. One
laboratory uses 2-aminoflourene and
aflatoxin 61, and another uses benzo(a)-
pyrene, 2-aminoanthracene, and pro-
flavine. Five laboratories do not indicate
what chemical they use.
For nonactivation assays using strain
TA1535 Ames recommends N-methyl-
N-nitrosoguanidine (MNNG) and de
Serres and Shelby recommend methyl
methanesulfonate (MMS). Six labora-
tories use MNNG exclusively. Nine
laboratories use sodium azide solely.
Another uses 1,3-propanesultone. One
laboratory uses MNNG, MMS, and
sodium azide. Another uses sodium
azide and 4-fluoro-3-nitrophenyl azide.
Still another uses sodium nitrite, N-
hexyl-N-nitro-N-nitrosoguanidine. One
laboratory uses MNNG, MMS, and 4-
Nitroquinoline-N-oxide, and five do not
say what chemical they use.
When using TA1537 Ames and de
Serres both recommend using 9-
aminoacridine. Eighteen laboratories
follow this recommendation. Five labor-
atories do not say what chemical they
use. One laboratory uses 4-fluoro-3-
nitrophenyl azide, and another uses
MNNG and 9-aminoacridine.
For TA1538 Ames suggests 2-amino-
fluorene and de Serres recommends 4-
nitro-0-phenylene diamine, 2-nitro-
fluorene, and hycanthone methanesul-
fonate. Thirteen laboratories use 2-
nitrofluorene only. Seven do not list the
chemical they use. One laboratory uses
Daunomycin exclusively, and another
uses 2-aminofluorene exclusively. One
laboratory uses 2-nitrofluorene and 4-
nitro-0-phenylene diamine while one
-------
uses 2-nitrofluorene and 4-fluoro-3-
nitrophenyl azide. One laboratory uses
MNNG and 4-nitroquinoline-N-oxide.
When using TA98 Ames recommends
4-nitroquinoline-N-oxide, Oaunomycin,
2-aminofluorene, and aflatoxin Bi. De
Serres recommends using 4-nitro-O-
phenylene diamine, 2-nitrofluorene,
and hycanthone methanesulfonate.
Fourteen laboratories use 2-ntirofluor-
ene only. Six laboratories do not list a
chemical. One laboratory uses Dauno-
mycin only and one uses 4-nitroquino-
line-N-oxide only. One laboratory uses
2-nitrofhJorene and hycanthone meth-
anesulfonate. Another uses 2-nitro-
fluorene and 4-fluoro-3-nitrophenyl
azide. Still another uses Daunomycin,'
MMS, and 4-nitroquinoline-N-oxide.
For strain TA100 Ames suggests
MMS, MNNG, 2-aminofluorene, afla-
toxin Bi, and 4-nitroquinoline-N-oxide.
De Serres' recommendations are sodium
azide, MMS, and nitrofurantoin. Nine
laboratories use sodium azide only, and
three use MNNG only. One laboratory
uses 1,3-propane sultone, and one uses
MMS; another uses benzo(a)pyrene
only. Five laboratories do not list the
chemical they use. One laboratory uses
MMS and MNNG. One laboratory uses
MNNG, MMS, sodium azide, and nitro-
furantoin. One laboratory uses sodium
azide, 4-fluoro-3-nitrophenyl azide.
Another uses MMS and 2-nitrofluorene.
Still another uses MNNG, MMS, and 4-
nitroquinoline-N-oxide.
Preparation of Control
Mutagens/Carcinogens
Ames recommends the disposable
sterile polystyrene screw cap tube as the
container of use for carcinogens and
lists four possible solvents: H20, DMSO,
ethanol, or p-dioxane. Fourteen labora-
tories do not discuss their method of
preparation. Two laboratories follow
Ames' procedure. Five others list only
the solvent used. Four laboratories list
either their storage container or proce-
dure.
Assay Procedure
Ames recommends the following
procedure for the assay. An aliquot of
0.1 ml from a 108 culture of Salmonella
is added to a tube containing 2 ml
molten top agar at 45°C, followed by the
sample to be tested and 0.5 ml of S-9
mix. The tube is rotated between the
palms and, within 20 sec, poured onto a
petri plate. The plates are left to harden
for one hour and then incubated in the
dark for two days at 37°C. De Serres and
Shelby recommended a culture of 1 or 2
x 109 concentration of Salmonella and
an extension of the incubation time
from 48 h to 48-72 h. They suggested
duplicate plating as the minimum with
triplicate plating preferred, and used ali-
quots of 0.2 fjg to 5 mg of sample. They
recommended both that sterility con-
trols include the solvent and S-9 mix,
and that spot checked phenotype moni-
toring be performed.
The most variation among the labora-
tories comes in the order in which
constituents are added. Half the labora-
tories indicate a preference to the order
of addition: Salmonella, sample, and S-
9. The other laboratories use different
permutations or do not list an order.
Temperatures for top agar vary from 43
to 56°C. Incubation times range from 36
to 72 h. Duplicate or triplicate plating is
recommended. Five laboratories substi-
tute the volume taken up by S-9 by using
KCI, saline, or buffer in a nonactivation
assay. Three laboratories place their
plates in sealed bags for the incubation
time.
Ames has revised his mixing tech-
nique: he now uses a vortex at low
speed. Eight laboratories mention using
a vortex in their protocols.
Three laboratories indicate use of
only a preincubation technique with the
Salmonella and sample.
Discussion
As a first step in establishing Quality
Assurance/Quality Control (QA/QC)
procedures for in vitro bioassays, the
Ames Salmonella plate incorporation
bioassay protocols from 25 laboratories
were compared. At this stage, no
attempt was made to evaluate a protocol
or to designate a preferred method.
In general, most laboratories follow
most of the procedures as outlined by
Ames; however, it appears that each
laboratory deviates from this standard
protocol in some manner. There was
strong concordance with Ames on the
selection of tester strains, the prepara-
tion of the S-9 mix, and the preparation
of the microsomal salt solution.
Most laboratories differ from the
Ames, et al., 1975 protocol in the
selection of some control compound
and in the actual assay exposure
procedure. Only one laboratory pre-
scribed the routine verification of
compound sensitivity for strains TA98
and TA100. Most procedures and media
preparation instructions were left out of
one or more protocols; however, a
laboratory SOP may have included
these instructions.
Comparison of current protocols may
improve both individual experimental
procedures and the consistency of
results from different laboratories In
addition, this study may help identify
monitorable parameters within the test
procedures so that adequate QA/QC
procedures can be established.
Stephanie Toney is with Northrop Services, Inc., Research Triangle Park, NC
27709; the EPA author Larry D. Claxton (also the EPA Project Officer, see
below) is with the Health Effects Research Laboratory, Research Triangle
Park, NC 27711.
The complete report, entitled "Comparison of Ames Salmonella typhimurium
Plate Incorporation Test Protocols," (Order No. PB 82-234 253; Cost: $10. SO,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
•US OPO:1M2-599-
-------
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Environmental Protection
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Center for Environmental Research
Information
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Penalty for Private Use $300
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