Registration Dossier

Administrative data

Description of key information

Lactide (18:1 mixture of L-lactide and m-lactide) was tested in dogs in a 2 week dose range finding study and a subsequent 90d full study similar to OECD 408. The primary toxic effect was irritation of the gastrointestinal tract at 100 mg/kg/d in the 90d study.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Published study, meets generally accepted scientific standards and is described in sufficient detail. L-lactide is the enantiomer of D-lactide and therefore suitable as read-across partner.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 409 (Repeated Dose 90-Day Oral Toxicity in Non-Rodents)
Deviations:
not specified
Principles of method if other than guideline:
Doses for the 13-wk study were selected based on the results of a 2-week study. In the 13-wk study, four dogs per sex were assigned to each of four treatment groups (dosed with lactide at 0, 4, 20 and 100 mg/kg body weight/day). Each dog received daily oral doses of one to six gelatin capsules containing lactide. Doses were administered at approximately 1 hr after feed was withdrawn, and at approximately the same time each day for 13 weeks. Control dogs received the same number of empty capsules as dogs of the corresponding sex in the highest dose group. Doses were calculated based on the body weight of each dog during the previous week.
GLP compliance:
not specified
Limit test:
no
Species:
dog
Strain:
Beagle
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc ( Madison, WI, USA)
- Age at study initiation: ranged from 5 to 10 months
- Fasting period before study: 1 hour before dosing
- Housing: individual housed in stainless-stell cages on racks and were exercised at least twice weekly throughout the quarantine and study period
- Diet (e.g. ad libitum): dogs were fed Certified Canine Chow 5007 (PMI Feeds, Inc) for approximately 2 hours each day
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 26°C
- Humidity (%): 35 - 85%
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:
oral: capsule
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
Each dog received daily oral doses of one to six gelatin capsules containing lactide. Doses were administered at approximately 1 h after feed was withdrawn, and at approximately the same time each day for 13 weeks.
Control dogs received the same number of empty capsules as dogs of the corresponding sex in the highest dose group. Doses were calculated based on the body weight of each dog during the previous week.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
SIngle daily dose
Remarks:
Doses / Concentrations:
0, 4, 20, 100 mg/kg bw/d for 13 weeks.
Basis:
actual ingested
No. of animals per sex per dose:
4
Control animals:
yes, concurrent vehicle
Observations and examinations performed and frequency:
Observations:
- Dogs were observed twice daily for mortality or moribundity.
- Cageside observations were performed daily, approximately 1 h after dosing.
- Once a week, each dog was removed from its cage and examined closely for detailed clinical signs of toxicity.
- Throughout each study:
dogs were weighed weekly, and food consumption was measured once a week over a 2-hour period.

Clinical pathology:
- blood and urine samples were obtained from each dog for clinical pathology and urinalysis determinations during quarantine, during week 5 and 9, and within 3 days prior to terminal sacrifice

Dogs were fasted overnight prior to blood collection for haematologic, clinical chemistry and coagulation analyses

Haematologic analyses included:
total leucocyte count, erythrocyte count, haemaglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, platelet count and differential leucocyte count. Reticulocyte counts and red blood cell morphology were evaluated.

Clinical chemistry analysis included:
By using a Roche Cobas Fara clinical chemistry analyser: blood urea nitrogen, creatinine, serum glucose, serum aspartate aminotransferase, serum alanine aminotransferase, alkaline phosphatase, glutamyl transferase, sodium, potassium, chloride, calcium, inorganic phosphate, total protein, albumin, albumin/total protein ratio, total bilirubin and cholesterol.

Coagulation analyses included:
Prothrombin time and activated partial prothrombin time, fibrinogen

Urine analyses included:
Urine specific gravity, urine microscopic sediment, urine pH, ketones, protein, glucose, bilirubin and occult blood
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Statistics:
- Groups means and standard deviations for: body weights, food consumption, clinical pathology parameters, for terminal body weights and for absolute and relative organ weights
- Body weights, food consumption and clinical pathology parameters were evaluated by two-way repeated ANOVA, and if significant by Dunnett's test
- Mean body weights, mean organ weights and organ/body, organ:brain ratios for each treated group were compared to those of the control group by a two-tailed Student's t-test for each sex
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Emesis once in each of two female dogs (one in the 0 mg/kg and one in the 100 mg/kg group during week 9). Bloody diarrhoea was seen once during week 6 in one female dog of the 100 mg/kg group
Mortality:
mortality observed, treatment-related
Description (incidence):
Emesis once in each of two female dogs (one in the 0 mg/kg and one in the 100 mg/kg group during week 9). Bloody diarrhoea was seen once during week 6 in one female dog of the 100 mg/kg group
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
stomach foci in one male/female from the 100 mg/kg , and one female from the 4mg/kg dose group
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
moderately severe ulceration of the stomach mucosa seen in one female dog of the high dose group
Histopathological findings: neoplastic:
no effects observed
Dose descriptor:
NOAEL
Remarks:
(systemic)
Effect level:
100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Dose descriptor:
LOAEL
Remarks:
(local)
Effect level:
100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: gastrointestinal irritation
Dose descriptor:
NOAEL
Remarks:
(local)
Effect level:
20 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Critical effects observed:
not specified

Table 1: Incidence of gross lesions in dogs treated for 13 weeks with oral doses of lactide
             
Dose group 0 mg/kg 4 mg/kg 20 mg/kg 100 mg/kg
Males
Stomach focus 0 0 0 1
 
Females
Stomach focus 0 1 0 1

Incidence= number of dogs in a given dose group with a given lesion. n=4 for all dose groups

Conclusions:
Lactide acts primarily, if not only, as an irritant after oral administration. 13 week NOAEL is 100 mg/kg bw/d.
Executive summary:

In a subchronic toxicity study lactide (18:1 mixture of l-lactide and m-lactide) was administered to 4 beagle dogs/sex/dose by capsule at dose levels of 4, 20, 100 mg/kg bw/day for 13 weeks.

The only apparent toxic effect at 100 mg/kg/day was gastrointestinal irritation. Therefore, the local LOAEL is 100 mg/kg/d. No systemic effects were reported at 100 mg/kg/d. Thus, the systemic NOAEL for orally administered lactide under the conditions in this study was considered to be 100 mg/kg/day.

This subchronic study in dog is acceptable and satisfies the principle requirement for a subchronic oral study similar to OECD 409 in dog.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
100 mg/kg bw/day
Study duration:
subchronic
Species:
dog

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Lactide is rapidly hydrolysed to lactic acid in water and in-vivo (gastric acid). Lactic acid is a ubiquitous and essential molecule of life. Lactate is non-toxic, any (local) effects are due to pH effects only.

In addition, in an oral toxicity (dose range finding) study, the read across partner lactide (18:1 mixture of L-lactide and m-lactide) was administered to beagle dogs by capsule at dose levels of 10, 100, 400, 1.000 and 2.500 mg/kg bw/day for 2 weeks, and 0, 4, 20 and 100 mg/kg/d for 13 weeks. The primary toxic effect of lactide in dogs was irritation of the alimentary tract. As irritating effects occurred down to a daily dose of 400 mg/kg bw (for 2 wks), the sub-chronic study was run with a maximum dose of 100 mg/kg bw/d.

At 1.000 and 2.500 mg/kg/d effects on body weight, and absolute and relative organ weights were reported in the 14-day dose range finding study for thymus and spleen. These effects were considered secondary to the irritation of the alimentary tract. In addition, a mild to moderate renal tubular regeneration was reported in all animals of the 2.500 mg/kg/d dose. Regeneration of the renal tubular epithelium is frequently seen as a reparative or adaptive change following tubular epithelial necrosis, and is suggestive of prior damage to this tissue. Although the mechanism of this effect is unknown, lactide toxicity cannot be excluded. Based on the possible renal toxicity the (systemic) LOAEL is 2.500 mg/kg bw/day. That's well above the limit dose of 1.000 mg/kg/d for a sub-acute toxicity study.

No systemic adverse effects were reported at the highest dose tested in the 90 d study (100 mg/kg/d). Therefore, the (systemic) NOAEL for orally administered lactide in a 90-d study in the dog is considered to be 100 mg/kg/day. The primary toxic effect after oral dosing was irritation of the gastrointestinal tract at 100 mg/kg/d.


Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Meets generally accepted scientific standards and is described in sufficient detail

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: other

Justification for classification or non-classification

D-lactide is to be considered non-toxic; the only effect are due to local irritation in the gastointestinal tract as a consequence of the formation of lacate derivates including lactoyl lactic acid and monomeric lactic acid. Therefore, based on the available data from the read across partner lactide, an 18:1 mixture of L-lactide and m-lactide, D-lactide does not warrant classification for repeated dose toxicity.