Zinc di(acetate)

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No specific test guideline was reported; however, the study is performed in similar way as described in OECD 408 guideline.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

(Only female rats were used)

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

5970-45-6

Cas Number:

5970-45-6

IUPAC Name:

5970-45-6

Constituent 2

Reference substance name:

Acetic acid, zinc salt, hydrate (2:1:2)

IUPAC Name:

Acetic acid, zinc salt, hydrate (2:1:2)

Details on test material:

- Name of test material (as cited in study report): Zinc acetate dihydrate
- Molecular formula (if other than submission substance): C4-H6-O4.Zn.2H2-O
- Molecular weight (if other than submission substance): 219.48
- Substance type: discrete
- Physical state: solid

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Interfauna Iberica, Barcelona, Spain
- Weight at study initiation: 70-90 g
- Housing: Animals were placed in individual metabolism cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

VEHICLE
The vehicle is water, but sugar was added to reduce the aversive effect of the zinc in the water.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

The solutions were prepared weekly.

Duration of treatment / exposure:

A period of three months.

Frequency of treatment:

The rats were exposed to test substance continously.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
160 mg/kg body weight/day
Basis:
nominal in water

Doses / concentrations 2

Remarks:

Doses / Concentrations:
320 mg/kg body weight/day
Basis:
nominal in water

Doses / concentrations 3

Remarks:

Doses / Concentrations:
640 mg/kg body weight/day
Basis:
nominal in water

No. of animals per sex per dose:

10 female animals per each dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: 1/5, 1/2.5, and 1/1.25 of acute oral dose.

Positive control:

No positive controls were used.

Examinations

Observations and examinations performed and frequency:

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were recorded prior to treatment and weekly throughout the study.
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: daily
HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of experiment
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: Forty
- Parameters checked in table were examined.

NEUROBEHAVIOURAL EXAMINATION: No

OTHER: The zinc concentration in organs and tissues was determined.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Other examinations:

Determination of zinc concentration in organs and tissues.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

effects observed, treatment-related

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

effects observed, treatment-related

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

not specified

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not specified

Details on results:

During the total 3-month treatment period same outstanding changes were found as regards to appearance, mortality and behaviour between the rats receiving the higher doses of zinc acetate (640 mg/kg bw/day) and the controls, Treated rats showed a tendency towards apathy and two animals in this group died throughout the study. Food consumption as well as the amount of feces excreted were about equal in all groups. There was no effect on weight gain caused by treatment.
With regard to the nutricional parameters measured, the drinking water ingested and the volume of urine excreted were always significantly lower for the 640 mg/kg bw/day group. Nevertheless, the animals receiving 160 and 320 mg/kg bw/day did not show significant differences in any of the nutritional parameters studied.

Effect levels

Dose descriptor:

NOEL

Effect level:

133.77 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: overall effects (Estimated results for Zinc Acetate anhydrous)

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

No treatment-related effects on organ weights or organ/body weight ratios were observed during the study (Table 1, P>0,05),

Table 1:        Fresh weights of organs from rats receiving zinc acetate in their drinking water for three months

		Dose (mg/kg/day)
	0	160	320	640
Brain	1,88± 0,11	1,83± 0,12	1,74± 0,15	1,72± 0,24
Heart	0,86± 0,10	0,76± 0,13	0,84± 0,09	0,66± 0,17
Lungs	1,44± 0,29	1,51± 0,37	1,39± 0,20	1,03± 0,14
Spleen	0,48± 0,24	0,46± 0,11	0,51± 0,15	0,29± 0,24
Liver	8,56± 0,75	8,33± 1,32	7,50± 1,29	5,02± 1,97
Kidneys	1,81± 0,17	1,71± 0,11	1,73± 0,21	1,61± 0,46

Results are presented as arithmetic means, No significant differences could be de detected by the Student's t test,

The Table 2 summarizes the hematological and plasma analyses carried out in the treatment and control animals after three months of treatment. The concentrations of urea and creatinina and plasma were significantly higher for the animals receiving 640 mg/kg/day zinc acetate than the control rats.

Table 2: Hematological and clinical chemical parameters* in rats dosed with zinc acetate for three months.

Dose (mg/kg/day)

	0	160	320	640
Hematocrit	(%) 46,7± 4,9	41,0± 12,7	43,5± 3,5	39,0± 11,8
Hemoglobin
(g/100 ml)	12,2± 0,7	14,5± 1,0	14,1± 2,7	10,3± 1,9
Glucose
(mg/10O ml)	163,5± 9,9	142,3± 29,1	156,3± 29,1	142,3± 8,5
GOT (U/l)	118,9± 22,1	96,6± 47,5	113,2± 25,5	141,6± 8,1
G.PT (U/l)	40,1± 10,9	50,4± 15,1	51,9± 7,0	42,1± 6,1
ALP (U/l)	136,9± 37,9	227,0± 19,8	228,4± 23,5	236,7± 38,7
Urea
(mg/100 ml)	39,5± 5,2	40,5± 11,4	35,5± 3,1	59,2± 4,2**
Creatinine
(mg/100 ml)	0,7± 0,21	1,7± 1,22	0,6± 0,24	4,4± 0,70**

The concentration of zinc in the tissues of rats are shown in Table 3. The highest concentrations were found in bone, liver and kidneys as well as in blood. A significant relationship between dose received and tissue concentrations can be seen. The most several histological lesions were observed in kidneys.

Table 3: Zinc concentrations* in organs and tissues of rats receiving zinc acetate for three months.

Dose (mg/kg/day)

	0	160	320	640
Brain	9.5 ± 1.9	9,4± 3,2	13,5± 1,8	15,4± 2,8
Liver	20,3±5,3	24,7± 5,7	47,6± 8,4*	59,9± 7,0**
Kidneys	15,0± 11,09	20,6± 4,9	41,1± 4,9**	38,3± 3,2**
Spleen	15,6± 12.05	15,9± 3,4	22,0± 3,6	36,4± 6,0*
Heart	10,5± 11,7	11,3± 1.8	16,8± 1,1*	21,9± 2,5**
Lungs	12,7± 12,4	14,2± 3,6	20,2± 1,3	20.7± 2,8
Bone	92,3± 121,3	127,3± 39,7	326,3± 47,6**	330,6± 58,6**
Muscle	14.5± 13,2	13,9± 1,6	18,0 ± 1.3	30,0± 9,1
Blood	3.4± 12,0	4,2± 1,7	16,3 ± 2,3**	21,1± 3,0***

 ^aZinc concentrations are expresed as µg/fresh weight, *P>0.05, **P<0.01, ***P<0.001 by the Student's t test 

Applicant's summary and conclusion

Conclusions:

The results of the assay have demostrated for zinc acetate anhydrous a toxicological no observable-effect level (NOEL) of 133.77 mg/kg bw/day in female rats.

Executive summary:

The repeated dose of zinc acetate 90-days oral toxicity study in rodents was carried out using 40 females Sprague-Dawley rats which were exposed to dihydrated zinc acetate in drinking water at concentrations of 0, 160, 320, and 640 mg/kg bw/day continuously during 3 months.

For animals receiving 640 mg/kg bw/day of zinc acetate the volume of urine excreted and the drinking water taken in were always lower than in the other groups. Concentrations of urea and creatinina in plasma were significantly higher for the animals of this group. The highest concentration of zinc was found in the bone, liver, and kidneys as well as in blood.

The results of the assay have demonstrated a toxicological no observable-effect level (NOEL) for zinc acetate anhydrous of 133.77 mg/kg bw/day in female rats.