Fatty acids, C16-18 (even numbered), ammonium salts

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1980

Materials and methods

Principles of method if other than guideline:

Groups of 20 male and 20 female six week old rats were fed diets containing 5, 10 or 20 % magnesium stearate. The diets were semi synthetic in which sodium caseinate replaced casein. The animals were weighed once weekly and food utilization and weight gain was calculated for each sex of all groups of rats. Blood samples were taken from 8 males and 8 females from each group prior to dosing and at 8 and 12 weeks. At the termination of the study, the rats were sacrificed and organs were weighed. Microscopic examination of tissues were performed on high dose and control animals.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Magnesium distearate

EC Number:

209-150-3

EC Name:

Magnesium distearate

Cas Number:

557-04-0

IUPAC Name:

magnesium dioctadecanoate

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 6 weeks old.
- Diet (e.g. ad libitum): See below "Details on oral exposure".
- Water (e.g. ad libitum): Acidified water (pH 3.5), ad libitum

Administration / exposure

Route of administration:

oral: feed

Vehicle:

not specified

Details on oral exposure:

The diets were semi synthetic in which sodium caseinate replaced casein. The carbohydrates of the diet were substituted by magnesium stearate as follows: 0 (control), 5, 10, 20 % in diet (magnesium stearate); 67.3, 62.3, 57.3 and 47.8 % in diet (carbohydrate)
The diets fed were considered isocaloric, as stearate has a calorific value of about 9, and a pilot study demonstrated that 35-40% of the stearate is absorbed at a 10% level in the diet.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

3 months

Frequency of treatment:

Daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

5 other: %

Remarks:

nominal in diet

Doses / concentrations 2

Dose / conc.:

10 other: %

Remarks:

nominal in diet

Doses / concentrations 3

Dose / conc.:

20 other: %

Remarks:

nominal in diet

No. of animals per sex per dose:

20 animals per sex and per dose.

Control animals:

yes, concurrent no treatment

Examinations

Observations and examinations performed and frequency:

BODY WEIGHT: Yes
- Time schedule for examinations: Once weekly.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food utilization was calculated for each sex of all groups of rats.

HAEMATOLOGY: Yes
- Blood samples were taken from 8 males and 8 females from each group prior to dosing and at 8 and 12 weeks.
- Parameters checked: Hemoglobin, packed cell volume (PCV), red cell count, total white cell count reticulocyte count, differential white cell count.

CLINICAL CHEMISTRY: Yes
- Blood samples were taken from 8 males and 8 females from each group prior to dosing and at 8 and 12 weeks.
- Parameters checked: Glucose, urea, aspartate amino transferase, alkaline phosphatase

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
At the termination of the study, the rats were sacrificed and the following organs were weighed: thymus, liver, kidneys, adrenals, testes/ovaries, heart, lungs, brain and pituitary.

HISTOPATHOLOGY: Yes
Samples of the organs listed above and the following tissues were taken for light microscopy: urinary bladder, stomach, duodenum, pancreas, jejunum, cecum, colon, thyroid, parathyroid, triceps, brachial muscle, ischiadic nerve, axillar lymph node, uterus, sternum, eye, Harderian gland, skin and submandibular gland. Microscopic examination was undertaken on the high dose and control animals only .

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Males at 20% group were quiet with slow and unsteady movements. Four males at 20% group died within the first 2 months and all had stone formation in the lower urinary pathways and the deaths were considered to be related to this finding. One other male in this group was incontinent. In the remaining males, the symptoms receded during the following 4 weeks.
There were no clinical effects in females in any group.

Mortality:

mortality observed, treatment-related

Description (incidence):

Four males at 20% group died within the first 2 months and the deaths were considered to be related to this finding.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The weight gains of the 20% males were significantly less than the corresponding controls during the first 8 weeks of the study.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No effects were reported.

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A reduction in PCV (P<0.01) was found in the 20% males compared to controls. No other hematological differences were reported.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No effects were reported.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The relative liver and kidney weights were lower (p<0.001) (see below Table 1).

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

In addition to the findings reported in the males that died in the 20% group, changes were also found in the renal pelvis and in the lower urinary pathways (due to stone formation) at autopsy in 4 males and one female in the 20 % group.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Nephrocalcinosis was seen in all females and in 12/20 males in the control group. In 18 of the females nephrocalcinosis was regarded as severe. Slight to moderate nephrocalcinosis was observed in 19/20 of the females in the 20% group and 7/20 of the males were affected only slightly.
Deposition of iron was found in various amounts in kidney and in liver, the amount was increased in the liver of both sexes in the 20% group.
Liver glycogen showed a marked decrease in males in the 20% group and no difference was found in the females.

HISTORICAL CONTROL DATA:
According to the authors the occurrence of nephrocalcinosis is a common finding in animals fed semi-synthetic diets. The increased magnesium content of the diet could explain the reduction of nephrocalcinosis in the 20% animals. A high magnesium content of the diet has also been previously associated with a greater incidence of stone formation in the lower part of the urinary tract.

Histopathological findings: neoplastic:

not specified

Other effects:

no effects observed

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

5 other: % in diet (~2500 mg/kg bw)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Target system / organ toxicity

Key result

Critical effects observed:

no

Any other information on results incl. tables

Table 1: The relative liver and kidney weights:

Dietary (%)	Sex	Liver (g/100 g bw)	Kidney (g/100 g bw)
0 (control)	Male	3.25±0.21	633±48.6
5	Male	3.13±0.21*	614±51.5
10	Male	2.99±0.23***	599±40.6*
20	Male	2.82±0.18***	640±80.7
0 (control)	Female	3.30±0.24	768±103
5	Female	3.33±0.18	661±86.5***
10	Female	3.31±0.31	667±54.0***
20	Female	3.16±0.23*	646±55.8***

 

* P< 0.05

*** P<0.001

 

Applicant's summary and conclusion

Conclusions:

The NOAEL-90 days for repeated dose toxicity by feed of Magnesium stearate was determined to be 5% in diet (~2500 mg/kg bw)(basis for effect: liver weight).

Executive summary:

A repeated dose toxicity study was performed on Magnesium stearate. Groups of 20 male and 20 female six week old rats were fed diets containing 5, 10 or 20 % magnesium stearate. The diets were semi synthetic in which sodium caseinate replaced casein. The animals were weighed once weekly and food utilization and weight gain was calculated for each sex of all groups of rats. Blood samples were taken from 8 males and 8 females from each group prior to dosing and at 8 and 12 weeks. At the termination of the study, the rats were sacrificed and organs were weighed. Microscopic examinations of tissues were performed on high dose and control animals. The weight gains of the 20% males were significantly less than he corresponding controls during the first 8 weeks of the study. Moreover, four males in this group died within the first 2 months and all had stone formation in the lower urinary pathways. Nephrocalcinosis was seen in both control and 20% dose groups in males and females. Deposition of iron was found in various amounts in kidney and in liver in both sexes in the 20% dose groups and liver glycogen showed a marked decrease but only in males. According to the authors the occurrence of nephrocalcinosis is a common finding in animals fed semi-synthetic diets. The increased magnesium content of the diet could explain the reduction of nephrocalcinosis in the 20% animals. A high magnesium content of the diet has also been previously associated with a greater incidence of stone formation in the lower part of the urinary tract. The authors concluded that when liver weight was used as a measure of adverse effect, the no effect level was estimated to be 5% magnesium stearate in the diet, corresponding to 2500 mg/kg body weight.