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Acute Toxicity: oral

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acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
EPA OPP 81-1 (Acute Oral Toxicity)
GLP compliance:
Test type:
standard acute method
Limit test:

Test material

Constituent 1
Reference substance name:
L-(+)-lactic acid
EC Number:
EC Name:
L-(+)-lactic acid
Cas Number:
2-hydroxypropanoic acid
Details on test material:

Test animals

other: albino
Details on test animals or test system and environmental conditions:
- Source: Charles River Breeding Laboratories, Inc., Wilmington, MA, USA
- Age at study initiation: young
- Weight at study initiation: 200 g (m) and 219 g (f)
- Fasting period before study: overnight
- Housing: individually in stainless steel, wire-bottomed cages that conformed to the size standards specified in DHEW Publication (NIH) 78.23.
- Diet (e.g. ad libitum): Purina Certified Rodent Chow 5002 was fed to the aniraals ad libitum during the quarantine and study periods except for fasting prior to dosing.
- Water (e.g. ad libitum): Filtered tap water was provided ad libitum through an automatic watering system
- Acclimation period: The animals were quarantined for at least 7 days after receipt.

The animal rooms were well ventilated and air-conditioned, and the temperature and humidity were monitored daily in these rooms during the quarantine and study periods. The temperature ranged from 68 to 74°F and the relative humidity to 68 percent in all 3 housing rooms with the following exceptions: relative humidity values were recorded as 29 percent on 3 days, 26 percent on one day, and 72 percent on one other day in room 247; and temperatures of 66°F or 67°F were recorded on 3 other days in room 247.
The animal room was lighted from approximately 6:00 a.m. to 6:00 p.m. (12-hour light/12-hour dark cycle) using automatic timers.

IN-LIFE DATES: The study was performed at ToxiGenics, Inc., 1800 East Pershing Road, Decatur, IL 62526 from November 3, 1983 to December 12, 1983.

Administration / exposure

Route of administration:
oral: gavage
Details on oral exposure:
In the morning of the days of dosing, body weights were recorded, doses were calculated, and a measured volume of the appropriate test article suspension was delivered to each animal by oral gavage in a single dose. Diet was returned to each surviving animal approximately 4 hours after test article administration.
3162, 3548, 3981, 4467, 5012, 5623, 6310 mg/kg bw
No. of animals per sex per dose:
Control animals:
Details on study design:
The duration of testing was 14 days for range-finding and 14 days or less for each main study dose level.
Animals were observed for mortality and abnormal clinical signs once each hour after dosing on day 0 (to the 4 to 5 hour interval). Observations for mortality and abnormal clinical signs were done twice daily thereafter for the duration of range-finding or main study testing. These twice daily obser- vations were done in the early morning and late afternoon of days l to 13 and in the morning of day 14. Body weights of all range-finding and main study animals were recorded prior to test article administration on the days of dosing (day 0). Body weights were also .recorded on days 7 and 14 for surviving range-finding and main study animals, and at the time found dead for other animals. All surviving range-finding animals were euthanized with carbon dioxide on day 14 and discarded. Range-finding animals found dead were also discarded. Range-finding animals were not examined at necropsy. All surviving main study animals were rendered unconscious with carbon dioxide and exsanguinated prior to necropsy on day 14. All external surfaces, orifices, and organs; cranial cavity; carcass; external and cut surfaces of the brain; abdominal, thoracic, and pelvic cavities and their viscera; and cervical tissues and organs of each main study animal (found dead or sacrificed on day 14) were examined at necropsy and all abnormal findings were recorded. Necropsies were conducted under the supervision of a qualified pathologist.
The oral LD50 value, the 95 percent confidence interval, the slope of the dose-response curve, and correction factors for 0 and 100 percent observed responses were calculated for each sex by computer program using a method adapted from Litchfield and Wilcoxon . Dose-response curves were prepared by computer program using the calculated LD50 data.
The mean, standard deviation, and Standard error were calculated for the main study body weight and test article administration data (milliliters of suspension administered and calculated milligram values).

Results and discussion

Effect levelsopen allclose all
Dose descriptor:
Effect level:
3 543 mg/kg bw
95% CL:
Remarks on result:
other: %
Dose descriptor:
Effect level:
4 936 mg/kg bw
95% CL:
Remarks on result:
other: %
All main study mortalties and range-finding mortalities (6,310 mg/kg) occurred after dosing on day 0 or in the morning of day l except for one main study female dosed at 3,162 mg/kg that was found dead in the morning of day 2. Range-finding animals dosed at 1,000, 1,585, 2,512, and 3,981 mg/kg and surviving main study animals were sacrificed after 14-day observation periods.
Clinical signs:
Lethargy, ataxia, prostration, irregular breathing, piloerection, squinting, lacrimation, salivation, crusty eyes and muzzle, loose stools, damp or yellow/brown stained fur, and moribund were abnormal clinical signs observed for main study animals as early as 0 to l hour after dosing and as late as day 2. Some of these abnormal signs were also observed for range-finding animals on the day of dosing. No other abnormal clinical signs were observed during the study.
Body weight:
Consistent body weight gains were observed on days 7 and 14 for all surviving range-finding and main study animals.
Gross pathology:
Abnormal necropsy findings were observed for all found dead main study animals, and for the 4 surviving main study females dosed at 3,162 mg/kg. Abnormalities observed during necropsy of found dead animals included: discolored lungs; firm texture of lungs; green foci on one lung; erosion of stomachs; dark, black, brown, and/or fluid contents of stomachs; black and/or brown discolored stomachs; a distended stomach with white mucosa; mucosal sloughing, ulceration, and hemorrhage of stomachs; discolored livers; white foei on livers; pale capsular areas, superficial erosion, or mottled livers; a discolored diaphragm; green-black or brown-black discolored kidneys; and red-brown exudate in the nasal and/or oral regions. Mottled lungs were observed during necropsy of 3 surviving animals dosed at 3,162 mg/kg, and thickened stomachs were also observed during necropsy of 2 surviving animals of the same group. No other abnormalities were observed during necropsy of all main study animals.

Applicant's summary and conclusion

Interpretation of results:
practically nontoxic
Migrated information Criteria used for interpretation of results: EU
The acute oral toxicity of lactic acid is clearly less than the limit for classification as harmful
Executive summary:

Lactic acid was administered to rats by oral gavage. The LD50 is higher than the upper limit for classification (2000 mg/kg bw).