Sodium (S)-lactate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1986-07-01 to 1986-09-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 81-6 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

When the study was conducted in 1986 the Local Lymph Node Assay was not yet adopted by the OECD Guidelines.

Test material

Test material information

Constituent 1

Reference substance name:

L-(+)-lactic acid

EC Number:

201-196-2

EC Name:

L-(+)-lactic acid

Cas Number:

79-33-4

Molecular formula:

C3H6O3

IUPAC Name:

(2S)-2-hydroxypropanoic acid

Specific details on test material used for the study:

- Name of the test material: SY-83
- Appearance: liquid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

female

Details on test animals and environmental conditions:

Young adult, female, outbred, Hartley guinea pigs were obtained from Charles River Breeding Laboratories, Inc. Portage, MI facility). Animals were housed individually in galvanized steel, wire-bottomed cages that conformed to the size standards specified in DHEW Publication (NIH) 78.23. The cages on each rack were numbered in a standard manner and a list of random numbers was generated by computer program for the number of cage positions used on each rack. After receipt, each animal was removed from the shipping container, housed in the appropriate randomly selected cage, and assigned a sequential animal number unique within ABC. The sequential animal number was listed on a cage card affixed to the front of each animal1s cage.
The animals were quarantined for at least 7 days after receipt and observed daily during the quarantine period for mortality, morbidity, and abnormal signs. Animals were examined during quarantine and only those considered to be in good health were used in this study. The quarantine and study room was cleaned daily and the cages were cleaned and sanitized as specified in ABC Standard Operating Procedures. Urine and feces feil through the wire mesh floor onto animal caging board. The cage boards were changed daily during the quarantine and study periods.
The animal room was well ventilated and air-conditioned. The temperature and humidity were monitored daily in this room during the quarantine and study periods; there were no deviations
from temperature and humidity ranges of 73 +5°F and 30-70%, respectively, which were considered to have had an adverse effect on the study. The animal room was lighted from approximately 6:00 a.m. to 6:00 p.m. (12-hour light/dark cycle) using automatic timers. The test article applications were completed between 9:59 a.m. and 10:29 a.m. during all 3 phases of the study (range-finding, nduction, and challenge).
Purina Guinea Pig Chow 5025 was fed ad libitum to all animals. Filtered tap water was provided ad libitum through an automatic watering system.

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

3, 10, 30, or 100% test article

Challenge

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

3, 10, 30, or 100% test article

No. of animals per dose:

10

Details on study design:

The duration of testing was 2 days for range-finding and 35 days for the main study. Two female guinea pigs were used in preliminary range-finding trials. Ten female guinea pigs were used in each main study group (test and naive control).
Animals were randomly assigned to the study by sequential animal number. However, any animal deemed unsuitable was not used, and the next acceptable sequentially numbered animal was used. The hair on the back or left flank, (induction) and/or flank (range-finding and challenge) of each animal was closely clipped with Oster electric clippers equipped with a number 40 (surgical) blade prior to dermal application. The hair was reclipped as necessary for subsequent induction applications and for dermal evaluations.
A 0.5 milliliter sample of the test article (100 %) and 0.5 milliliter samples of 30, 10, or 3% suspensions of the test article in deionized water were placed on separate 4 × 4 centimeter Webril patches, attached to Blenderm tape, and each of these concentrations was applied to a prepared site on a range-finding animal (2 concentrations were evaluated per animal). The 100 % test article concentration was selected for induction and challenge applications since dermal reactions were minimally irritating at this range-finding test site. After two induction applications the concentration was reduced to 30% and the test site was changed to the left flank. During the induction phase, 10 guinea pigs assigned to the test group received two 0.5 milliliter applications of the test article (100 %) and seven 0.5 milliliter applications of the test article (30 %) on 4 × 4 centimeter Webril patches attached to Blenderm tape. The 10 guinea pigs assigned to the naive control group remained untreated during the test group induction phase.
The induction applications were made 3 times each week (Monday, Wednesday, and Friday) until all 9 induction applications had been applied. Two weeks after the ninth induction application, each animal of both the test group and the naive control group received a single 0.5 milliliter challenge application of the test article (100 %) on the right flank. Webril patches (4x4 centimeter) attached to Blenderm tape were also used at the challenge.
During the range-finding, induction, and challenge phases, the Webril patches containing the test article were applied to the prepared sites and the entire trunk of each animal was wrapped with an impervious binder consisting of plastic wrap, adhesive tape, and masking tape. After a 6 hour (± 30 minutes) exposure period, the binders and patches were removed. The sites on each animal were evaluated for erythema, edema, and other lesions 24 and 48 hours (± 2 hours at each interval) after the test article applications (range-finding, each induction, and the challenge). Dermal reaction scores were assigned using the grading system presented in Table l of this report. Other dermal reactions observed were also recorded. Individual body weight values were determined for range- finding animals prior to application and prior to sacrifice. Individual body weight values were determined for test animals and naive control animals on the day of the initial induction application (day 0) and on the day of the 48-hour challenge evaluations (day 35). All animals were observed for abnormal clinical signs and mortality at least once daily during testing. All range-finding and main study animals were euthanized by asphyxiation with carbon dioxide and discarded at termination of testing. observed for abnormal clinical signs and mortality at least once daily during testing. All range-finding and main study animals were euthanized by asphyxiation with carbon dioxide and discarded at termination of testing.

Positive control substance(s):

yes

Remarks:

dinitrochlorobenzene (historical data)

Results and discussion

Positive control results:

Erythema and edema according to Draize (1979) and for other dermal reactions at 24 and 48 hours following each induction and challenge application. Results are presented for testing on 3 groups of 10 guinea pigs. In the first 24 hrs of the challenge test, 8, 8 and 10 out of 10 animals showed positive sensitization reaction to the positive control (DNCB), and 48 hours after the beginning of the test, 8, 8 and 9 out of 10 animals still presented positive reaction to DNCB.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100% test material

No. with + reactions:

9

Total no. in group:

10

Clinical observations:

All effects observed were deemed irritation, not sensitization

Remarks on result:

no indication of skin sensitisation

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100% test material

No. with + reactions:

8

Total no. in group:

10

Clinical observations:

All effects observed were deemed irritation, not sensitization

Remarks on result:

no indication of skin sensitisation

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

100% test material

No. with + reactions:

9

Total no. in group:

10

Clinical observations:

All effects observed were deemed irritation.

Remarks on result:

no indication of skin sensitisation

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

100% test material

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

All effects observed were deemed irritation.

Remarks on result:

no indication of skin sensitisation

Results 5

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

0.5 mL 0.1% DCNB

No. with + reactions:

28

Total no. in group:

30

Remarks on result:

positive indication of skin sensitisation

Remarks:

Historical positive control data with similar study design used

Results 6

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

0.5 mL of 0.1% of DCNB

No. with + reactions:

25

Total no. in group:

30

Remarks on result:

positive indication of skin sensitisation

Applicant's summary and conclusion

Interpretation of results:

other: CLP criteria not met

Conclusions:

Based on the result the test item is not considered to be sensitising to the skin. Therefore, classification for skin sensitisation according to the CLP Regulation 1272/2008 is not warranted.

Executive summary:

This study was conducted to evaluate the contact dermal sensitization potential of L(+)-lactic acid using a method described in the EPA Guidelines, 1982 (modification of the Buehler Closed Patch Technique) as described in American Biogenics Corporation (ABC) protocol A330. No mortalities occurred and all animals gained body weight. The test article (100%) produced very slight erythema at 3 sites and very slight edema at 1 site after the 1st induction. Erythema grades increased in severity after the 2nd induction application. One site was graded as severe erythema, however, this grade was given a 4 due to pinpoint pitting of the skin and scab formation, not for redness. Due to the increase of severity of the reactions, the concentration of the test article was reduced to 30% and the induction site was changed to the left flank. Very slight erythema was noted after the 5th induction application. Grades ranging from very slight to severe erythema were noted from the 7th to the 9th induction applications. Again, the severe (grade 4) reactions were given this grade due to pinpoint pitting of the skin and the eschar formation, not for redness.

After the challenge application, the test article (100%) produced grade 4 erythema in up to 6 test animals. These gradings were very similar in character as those seen during the induction applications, that is, pinpoint pitting of the skin and eschar formation, very little redness. These reactions were considered to be irritation reactions, not sensitization reactions. Other reactions noted at challenge for the test animals were very slight to moderate erythema, and very slight to moderate edema. The test article (100%) produced grade 4 erythema in up to 8 naive control animals. These gradings were also pinpoint pitting of skin and eschar formation with very little redness. These reactions were considered to be irritation reactions, not sensitization reactions. Other reactions noted for the naive control animals were very slight to moderate erythema and very slight to moderate edema. The reactions seen in the naive control animals at the challenge application were similar to the reactions seen for the test group animals and L(+)-lactic acid was not considered to be a contact dermal sensitizer.