Oxalic acid

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 06, 2016 to March 13, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Oxalic acid dihydrate

Cas Number:

6153-56-6

Molecular formula:

C2O4H2.2H2O

IUPAC Name:

Oxalic acid dihydrate

Test material form:

solid: crystalline

Specific details on test material used for the study:

Identification Acido oxalico - STD
Appearance Fine White Crystal
Chemical Name Oxalic Acid Dihydrated
Batch Number 15000900
CAS No. 6153-56-6
Manufactured by OXAQUIM S.A
Supplied by OXAQUIM S.A
Purity (%) 99.6%
Molecular Weight 126.07 g/mol
Molecular Formula C2O4H2.2H2O
Manufacture Date May 21, 2015
Expiry Date May 20, 2017
Stability of the test item 1 year
Storage Conditions Room Temperature (20 to 30 oC)

Test animals

Species:

rat

Strain:

Wistar

Details on species / strain selection:

Rat is chosen as the test system because this species is commonly used for repeated dietary toxicity testing and it meets the regulatory requirement of most of the regulatory agencies

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Laboratories India Private Limited
- Females (if applicable) nulliparous and non-pregnant: [yes]
- Age at study initiation: 7 - 9 Weeks
- Weight at study initiation: Males - 211.6 to 258.2 g, Females - 155.2 to 194.1 g
- Housing: In groups of two animals of same sex in Polycarbonate cages (Approximate internal dimensions of 365 mm x 202 mm x 180 mm height) with corncob bedding
- Diet (e.g. ad libitum): Teklad Certified Global 14% Protein Rodent Maintenance Diet (Lot No. 2014C-061716MA) from Envigo was provided ad libitum
- Water (e.g. ad libitum): Aquaguard filtered tap water was provided ad libitum
- Acclimation period: 7 days for Step I, 10 days for Step II and 14 days for Step III animals of Allocation A and B under laboratory conditions, after veterinary examination

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.1 to 22.1°C
- Humidity (%): 54 to 64%
- Air changes (per hr): air-conditioned with adequate (above 10) air changes per hour
- Photoperiod (hrs dark / hrs light): light cycle of 12 hours light and 12 hours dark

IN-LIFE DATES: From: March 14, 2016 To: January 31, 2017 (Last Necropsy)

Administration / exposure

Route of administration:

oral: feed

Details on route of administration:

Dietary route is the intended route of administration in humans

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): Weekly twice
- Diet preparation: Dietary admixtures were prepared using the powdered feed and the same was used for bolus preparation.

Test item was triturated and weighed into a tared glass beaker using a sartorius weighing balance and mixed with powdered feed to prepare the pre-mix. Pre-mix was then used to prepare the low, intermediate and high dose concentrations. Required amount of pre-mix and powdered feed was mixed to achieve different dose concentrations in feed. An appropriate amount of water was added to aid bolus. The prepared bolus was provided to the animals. Feed for the control animals was prepared similarly without addition of test item

- Storage temperature of food: Room temperature

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The analytical method was validated and the linearity response was found to be linear (r2 = 1.000) in the range of 10 to 500.1 mg.
The recovered content was found homogeneously distributed in the feed for main study at concentrations 250 mg/L, 500 mg/L and 1000 mg/L for the test item respectively. (i.e. % coefficient of variation (RSD) ranged in between 0.00 to 6.11) and for Dose range finding study at concentrations 1000 mg/L, 5000 mg/L and 10000 mg/L for the test item respectively. (i.e. % coefficient of variation (RSD) ranged in between 0.52 to 3.00).
The recovered content obtained in all the dose groups was in agreement with the target concentration (i.e. ranged between 91.42 % to 104.48 % for main study and 93.95 % to 97.19 % for dose range finding study)

Duration of treatment / exposure:

Duration of treatment 90 days
Duration of recovery 28 days

Frequency of treatment:

Daily with feed

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

250 ppm

Remarks:

low dose

Doses / concentrations 2

Dose / conc.:

500 ppm

Remarks:

medium dose

Doses / concentrations 3

Dose / conc.:

1 000 ppm

Remarks:

High dose. The calculated mean intake of test item at the doses of 0, 250, 500 and 1000 PPM were equivalent to 0, 16, 31 and 63 mg/kg body weight/day respectively. This was selected since in the dose range finding study at 10000 and 5000 PPM, lesions in the kidney were noted.

In 28-d dose range finder “Histopathology reveals mineralization of test item in kidneys. Considering these observations at 10 000 and 5000 PPM, the dose of 1000 PPM was selected as high dose for the 90 day study.

No. of animals per sex per dose:

10 per sex and dose

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: Dose range finding was carried out to confirm the high dose level of test item for main study. Six groups, each consists of 4 male and 4 female animals were used. Test item was administered through diet for 28 days at doses of 1000, 5000 and 10000 PPM and followed by 14 days reversal period. Based on the results of dose range finding study, 250, 500 and 1000 PPM doses are selected for main study

In 28-d dose range finder, histopatology reveals mineralization of test item in kidneys. Considering these observations at 10000 and 5000 ppm, the dose of 1000 ppm was selected as high dose for the 90 day study.


- Rationale for animal assignment: Animals were selected and grouped based on stratified randomization by using body weights. Computerized statistical analysis was used for randomization (Excel programme)
- Post-exposure recovery period in satellite groups: 28 days

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once during acclimatization, week 1, week 6, week 13 and week 17

BODY WEIGHT: Yes
- Time schedule for examinations: Once Weekly

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

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Once during acclimatization, during week 13 in all animals of groups 1 (control) and 4 (high dose)

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Week 13 - Group 1 to 4 (Allocation A) and Week 17 - Group 1R and 4R (Allocation B)
- Anaesthetic used for blood collection: Yes (identity)
- Animals fasted: Yes
- How many animals: 120 animals (60 males + 60 females)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Week 13 - Group 1 to 4 (Allocation A) and Week 17 - Group 1R and 4R (Allocation B)
- Anaesthetic used for blood collection: Yes (identity)
- Animals fasted: Yes
- How many animals: 120 animals (60 males + 60 females)

URINALYSIS: Yes
- Time schedule for collection of urine: Week 13 - Group 1 to 4 (Allocation A) and Week 17 - Group 1R and 4R (Allocation B)
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: end of last week of treatment
- Dose groups that were examined: all groups
- Battery of functions tested: sensory activity / grip strength / motor activity: all

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

The following statistical methods were used to analyze the body weight, feed consumption, functional observation battery, organ weights as well as clinical pathology data.
•Data are summarized in tabular form. Statistical analysis was performed using “Statplus” program.
•All the data were checked for normality with Shapiro-Wilk W test
•All the data were checked for homogeneity with Bartlett’s Chi-square test
•For comparing more than 2 groups, If data passed Normality & Homogeneity then ANOVA was done, Otherwise Kruskal Wallis Test was done followed by appropriate Post-hoc tests when p < 0.05
•For comparing 2 groups, when data passed Normality & Homogeneity then Student T-test was done, Otherwise Mann-Whitney U Test was done. If p < 0.05 the compared groups are said to be significantly different
•Values are summarized as mean ± standard deviation (SD)

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

No clinical signs were observed in any of the animals treated with test item at the doses of 250 (low dose), 500 (intermediate dose) and 1000 PPM (high dose) throughout the treatment period. No clinical signs were observed in any of the animals during recovery period

Mortality:

no mortality observed

Description (incidence):

No mortality was observed in any of the animal treated with test item at dose levels of 250, 500 and 1000 PPM, throughout the experimental and recovery periods

Body weight and weight changes:

no effects observed

Description (incidence and severity):

During the 90 consecutive days of treatment period, the body weight (g) and body weight gain (%) in animals across all the dose groups was found to be non significant when compared with control animals. No significant difference were observed in high dose recovery group when compared with control recovery group.
The body weight of all the animals was within the normal range of variability commonly recorded for this species, strain and age

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

During the 90 consecutive days of dosing period, the quantity of feed consumed by animals across different dose groups was found to be non significant and comparable with the control animals. There was significant increase in feed consumption in male recovery (G4R) animals at weeks 3, 4 and 8 and significant decrease at weeks 15 and 16 when compared with control recovery group (G1R). In female recovery (G4R) animals, there was significant decrease at week 16 when compared with control recovery group (G1R)

OXALIC ACID was administered to Wistar rats at the doses of 0, 250, 500 and 1000 PPM in the diet for 90 days. The calculated mean intake of test item at the doses of 0, 250, 500 and 1000 PPM were equivalent to 0, 16, 31 and 63 mg/kg body weight/day respectively. This was selected since in the dose range finding study at 10000 and 5000 PPM, lesions in the kidney were noted.

Ophthalmological findings:

no effects observed

Description (incidence and severity):

Opthalmological examiniation did not reveal any abnormalities during acclimatization and in the control and high dose treated animals, at the end of treatment period

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Hematology parameters viz Erythrocyte count (RBC), Hemoglobin (Hb), Hematocrit (PCV), Mean corpuscular volume (MCV), Mean corpuscular hemoglobin (MCH), Mean corpuscular hemoglobin concentration (MCHC) and Differential leukocyte count (DC) did not show any toxicologically relevent findings in both the sexes. In males, there was significant decrease in platelet (thrombocyte) count (PLT) (G3) and white blood cell count (WBC) (G2 and G4) as compared with control group (G1). In females, there was significant decrease in white blood cell count (WBC) (G4) as compared with intermediate dose group (G3). Significant increase in neutrophils (G4) as compared with low dose group (G2). Significant decrease in lymphocytes (G4) as compared with low dose group (G2). Significant increase in basophils (G4) as compared with intermediate dose group (G3). Significant decrease in prothrombin time (PT) (G4) as compared with control (G1) and low dose group (G2) and there was significant increase in activated partial thromboplastin time (APTT) (G3) as compared with control group (G1) at the end of week 13. In recovery males, there was significant decrease in white blood cell count (WBC) (G4R) as compared with control recovery (G1R) at the end of week 17. The changes observed in the hematological parameters are marginal and could not be attributed to the test item administartion as these values were within biological variation

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Clinical biochemistry parameters viz Glucose (GLU), Urea, BUN, Calcium, Cholesterol (CHOL), Triglycerides (TRIGL), Alanine aminotransferase (ALT), Bilirubin (BIL), Sodium (Na+), Total protein (TPO) and Globulin (GLB) did not show any toxicologically releavant findings in both the sexes in treatment and recovery groups. In males, there was significant decrease in chloride (Cl-) (G2) as compared with control group at the end of week 13. in females, there was significant increase in alkaline phosphatase (ALP) (G4) when compare with control (G1), low (G2) and intermediate (G3) dose groups and significant decrease in chloride (Cl-) (G2) as compared with control group at the end of week 13. In recovery males, there was significant decrease in aspartate aminotransferase (AST) and phosphorous (PHOS) (G4R) when compared with control recovery (G1R) group. Significant increase in albumin (ALB) and albumin/globulin ratio (A/G) (G4R) when compared with control recovery (G1R) group. In recovery females, significant increase in potassium (K+) and creatinine (CREA) (G4R) when compared with control recovery (G1R) group at th end of week 17. The changes observed in the clinical biochemistry parameters are marginal and could not be attributed to the test item administartion as these values were within biological variation

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

Urine analysis parameters (volume, specific gravity, colour, clarity, pH, Erythrocytes, urobillinogen, bilirubin, proteins and glucose and microscopic examination) did not reveal any test item related changes in both the sexes during treatment and recovery periods. In males, there was significant increase in crystals (G3) when compared with control group (G1) at the end of week 13. In recovery males, there was significant increase in ketone bodies, leukocytes, pus cells and crystals (G4R) when compared with control recovery group (G1R) at the end of week 17

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

Functional observation battery parameters viz grip strength (Forelimbs and Hind limbs), Rotarod, Urine pools, Rearing, Fecal bolus, Hind limb foot splay and IR Actimeter did not show any toxicological significant changes in all the treated groups when compared with control group. In treatment males, there was significant decrease in forelimbs of grip strength (G3) when compared with control group (G1). In treatment females, there was significant increase in rearing (G3) when compared with control group (G1). In recovery males, there was significant increase in Rotarod, urine pools and IR Actimeter (G4R) when compared with control recovery group (G1R) at the end of week 13

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

No test item related statistical significance was observed in absolute and relative organ weights of male animals during treatment and recovery period. In treatment groups, significantly higher absolute and relative weight of adrenals was observed in male animals of intermediate dose (G3) group compared to control (G1) group. No significant difference was observed in absolute and relative weight of female animals. In recovery groups, significantly lower absolute and relative weight of thymus was observed in male animals of high dose recovery (G4R) group compared to control recovery (G1R) group. In female animals, significantly lower absolute and relative weight of adrenals was observed in high dose recovery (G4R) group compared to control recovery (G1R) group and significantly lower absolute weight of brain in high dose recovery (G4R) group compared to control recovery (G1R) group. Despite these differences, microscopically no test item-related change was observed in these organs evaluated in treatment group. Hence, the changes observed in organ weight were considered to be due to changes in body weight or as biological variation

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Necropsy performed at the end of the treatment and recovery period, no test item related findings were observed macroscopically in all treated male and female animals. No gross abnormality was observed in control group animals. Macroscopically, small sized testes, epididymides, prostate, seminal vesicles with coagulating glands were observed in one male animal of intermediate dose (G3) group. Distended uterus with watery content was observed in five female animals each of control (G1) and of intermediate dose (G3) groups, six female animals of low dose (G2) and seven female animals of high dose (G4) group. In recovery groups, distended uterus with watery content was observed in six female animals of control recovery (G1R) and two female animals of high dose recovery (G4R) group. In addition, hydronephrosis was observed in one female animal of control recovery (G1R) group. These findings were considered as incidental and to be gender, congenital and/or physiology related

Histopathological findings: non-neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

Microscopic examination revealed no abnormality attributable to the test item OXALIC ACID in high dose (1000 PPM) group. Most of the tissues evaluated were within normal histological limits. The histopathological findings observed in various tissues during evaluation of test item group animals were comparable with control group and were considered incidental. These changes observed can usually be considered to be species, age, gender, physiological or mode of death related and are covered in background historical data of pathology

Details on results:

No Observed Adverse Effect Level (NOAEL) – 1000 PPM

Applying the formula:

RFC = AFC/7 + [bw start of week 1 + bw gain during week/2]

Is obtained an Average test item consumed during the 90 day study of = 63 mg/kg bw day

Since no adverse effects were observed at highest tested dose i.e., 1000 PPM, the same was selected as NOAEL. The 1000 PPM is equivalent to 63 mg/kg body weight (actual test item consumed by the animals).
Test item (Oxalic acid dehydrate) as is basis = 63 mg/kg

Effect levels

1

Key result

Dose descriptor:

NOAEL

Effect level:

>= 1 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

behaviour (functional findings)

body weight and weight gain

clinical biochemistry

clinical signs

food consumption and compound intake

gross pathology

haematology

histopathology: non-neoplastic

mortality

ophthalmological examination

organ weights and organ / body weight ratios

urinalysis

2

Key result

Dose descriptor:

NOAEL

Effect level:

ca. 63 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Remarks on result:

other: No Observed Adverse Effect Level (NOAEL) – 1000 ppm. This value corresponds to 63 mg/kg bw/d, according to calculations accordig the formula: RFC (Relative Feed Consumption) = AFC/7 + [bw start of week 1 + bw gain during week/2]

Target system / organ toxicity

Key result

Critical effects observed:

no

Any other information on results incl. tables

 Toxic response/effects by sex and dose level

 

Toxic response/effects	Dose Level	Sex
		Male	Female
Mortality/Viability	250 PPM   500 PPM   1000 PPM	No mortality	No mortality
Clinical Signs		No clinical signs	No clinical signs
Ophthalmoscopy		No abnormalities	No abnormalities
Body Weight		No Significance observed	No Significance observed
Body Weight Changes		No Significance observed	No Significance observed
Feed Consumption		Significance observed, but not treatment related	Significance observed, but not treatment related
Hematology		Significance observed, but not treatment related	Significance observed, but not treatment related
Biochemistry		Significance observed, but not treatment related	Significance observed, but not treatment related
Urinalysis		Significance observed, but not treatment related	No Significance observed
FOB		Significance observed, but not treatment related	No Significance observed
Organ Weights		Significance observed, but not treatment related	Significance observed, but not treatment related
Histopathology		Incidental changes, but not treatment related	Incidental changes, but not treatment related

Applicant's summary and conclusion

Conclusions:

Repeated Dose 90 Days Dietary Toxicity Study with OXALIC ACID in Wistar Rats
This study was conducted based on the OECD Guidelines for the Testing of Chemicals, Section 4, Health Effects, Number 408, September 21, 1998.
The purpose of this study was to assess the toxicity of OXALIC ACID when administered to Wistar rats through diet for a period of 90 days. The reversibility of treatment related changes was assessed after a treatment free 28 day recovery period
Dose levels for main study are selected based on Dose Range Finding observation and results. Dose levels for main study were 250 PPM (low dose), 500 PPM (intermediate dose) and 1000 PPM (high dose). The test item was mixed with diet and administered to wistar rats. Each group consisting of ten males and ten females were used for the main study.
The following observations were performed: Mortality/viability, clinical signs, Ophthalmoscopy, body weights, feed consumption, dose formulation analysis, functional observation battery, clinical pathology, macroscopic and microscopic examination, organ weights and histopathology of the preserved tissues.
Statistical analysis was performed using Stat plus software to compare the significant difference between treatment and control group of animals (t-test/ANOVA).
Results:
No mortality was observed in any of the animal treated with test item at dose levels of 250, 500 and 1000 PPM, throughout the experimental and recovery periods.
No clinical signs were observed in any of the animals treated with test item at the doses of 250 (low dose), 500 (intermediate dose) and 1000 PPM (high dose) throughout the treatment period. No clinical signs were observed in any of the animals during recovery period.
Opthalmological examiniation did not reveal any abnormalities during acclimatization and in the control and high dose treated animals, at the end of treatment period.
During the 90 consecutive days of dosing period, the quantity of feed consumed by animals across different dose groups was found to be non significant and comparable with the control animals. There was significant increase in feed consumption in male recovery (G4R) animals at weeks 3, 4 and 8 and significant decrease at weeks 15 and 16 when compared with control recovery group (G1R). In female recovery (G4R) animals, there was significant decrease at week 16 when compared with control recovery group (G1R).
During the 90 consecutive days of treatment period, the body weight (g) and body weight gain (%) in animals across all the dose groups was found to be non significant when compared with control animals. No significant difference were observed in high dose recovery group when compared with control recovery group. The body weight of all the animals was within the normal range of variability commonly recorded for this species, strain and age.
Functional observation battery parameters viz grip strength (Forelimbs and Hind limbs), Rotarod, Urine pools, Rearing, Fecal bolus, Hind limb foot splay and IR Actimeter did not show any treatment related significant changes in all the treated groups when compared with control group. In treatment males, there was significant decrease in forelimbs of grip strength (G3) when compared with control group (G1). In treatment females, there was significant increase in rearing (G3) when compared with control group (G1). In recovery males, there was significant increase in Rotarod, urine pools and IR Actimeter (G4R) when compared with control recovery group (G1R) at the end of week 13.
Hematology parameters viz Erythrocyte count (RBC), Hemoglobin (Hb), Hematocrit (PCV), Mean corpuscular volume (MCV), Mean corpuscular hemoglobin (MCH), Mean corpuscular hemoglobin concentration (MCHC) and Differential leukocyte count (DC) did not show any toxicologically relevent findings in both the sexes. In males, there was significant decrease in platelet (thrombocyte) count (PLT) (G3) and white blood cell count (WBC) (G2 and G4) as compared with control group (G1). In females, there was significant decrease in white blood cell count (WBC) (G4) as compared with intermediate dose group (G3). Significant increase in neutrophils (G4) as compared with low dose group (G2). Significant decrease in lymphocytes (G4) as compared with low dose group (G2). Significant increase in basophils (G4) as compared with intermediate dose group (G3). Significant decrease in prothrombin time (PT) (G4) as compared with control (G1) and low dose group (G2) and there was significant increase in activated partial thromboplastin time (APTT) (G3) as compared with control group (G1) at the end of week 13. In recovery males, there was significant decrease in white blood cell count (WBC) (G4R) as compared with control recovery (G1R) at the end of week 17. The changes observed in the hematological parameters are marginal and could not be attributed to the test item administartion as these values were within biological variation.
Clinical biochemistry parameters viz Glucose (GLU), Urea, Cholesterol (CHOL), Triglycerides (TRIGL), Alanine aminotransferase (ALT), Bilirubin (BIL), Sodium (Na+), Total protein (TPO) and Globulin (GLB) did not show any toxicologically releavant findings in both the sexes in treatment and recovery groups. In males, there was significant decrease in chloride (Cl-) (G2) as compared with control group at the end of week 13. in females, there was significant increase in alkaline phosphatase (ALP) (G4) when compare with control (G1), low (G2) and intermediate (G3) dose groups and significant decrease in chloride (Cl-) (G2) as compared with control group at the end of week 13. In recovery males, there was significant decrease in aspartate aminotransferase (AST) and phosphorous (PHOS) (G4R) when compared with control recovery (G1R) group. Significant increase in albumin (ALB) and albumin/globulin ratio (A/G) (G4R) when compared with control recovery (G1R) group. In recovery females, significant increase in potassium (K+) and creatinine (CREA) (G4R) when compared with control recovery (G1R) group at th end of week 17. The changes observed in the clinical biochemistry parameters are marginal and could not be attributed to the test item administartion as these values were within biological variation.
Urine analysis parameters (volume, specific gravity, colour, clarity, pH, Erythrocytes, urobillinogen, bilirubin, proteins and glucose and microscopic examination) did not reveal any test item related changes in both the sexes during treatment and recovery periods. In males, there was significant increase in crystals (G3) when compared with control group (G1) at the end of week 13. In recovery males, there was significant increase in ketone bodies, leukocytes, pus cells and crystals (G4R) when compared with control recovery group (G1R) at the end of week 17.
No test item related statistical significance was observed in absolute and relative organ weights of male animals during treatment and recovery period. In treatment groups, significantly higher absolute and relative weight of adrenals was observed in male animals of intermediate dose (G3) group compared to control (G1) group. No significant difference was observed in absolute and relative weight of female animals. In recovery groups, significantly lower absolute and relative weight of thymus was observed in male animals of high dose recovery (G4R) group compared to control recovery (G1R) group. In female animals, significantly lower absolute and relative weight of adrenals was observed in high dose recovery (G4R) group compared to control recovery (G1R) group and significantly lower absolute weight of brain in high dose recovery (G4R) group compared to control recovery (G1R) group. Despite these differences, microscopically no test item-related change was observed in these organs evaluated in treatment group. Hence, the changes observed in organ weight were considered to be due to changes in body weight or as biological variation.
Necropsy performed at the end of the treatment and recovery period, no test item related findings were observed macroscopically in all treated male and female animals. No gross abnormality was observed in control group animals. Macroscopically, small sized testes, epididymides, prostate, seminal vesicles with coagulating glands were observed in one male animal of intermediate dose (G3) group. Distended uterus with watery content was observed in five female animals each of control (G1) and of intermediate dose (G3) groups, six female animals of low dose (G2) and seven female animals of high dose (G4) group. In recovery groups, distended uterus with watery content was observed in six female animals of control recovery (G1R) and two female animals of high dose recovery (G4R) group. In addition, hydronephrosis was observed in one female animal of control recovery (G1R) group. These findings were considered as incidental and to be gender, congenital and/or physiology related.
Microscopic examination revealed no abnormality attributable to the test item OXALIC ACID in high dose (1000 PPM) group. Most of the tissues evaluated were within normal histological limits. The histopathological findings observed in various tissues during evaluation of test item group animals were comparable with control group and were considered incidental. These changes observed can usually be considered to be species, age, gender, physiological or mode of death related and are covered in background historical data of pathology.
The analytical method was validated and the linearity response was found to be linear (r2 = 1.000) in the range of 10 to 500.1 mg.
The recovered content was found homogeneously distributed in the feed for main study at concentrations 250 mg/L, 500 mg/L and 1000 mg/L for the test item respectively. (i.e. % coefficient of variation (RSD) ranged in between 0.00 to 6.11) and for Dose range finding study at concentrations 1000 mg/L, 5000 mg/L and 10000 mg/L for the test item respectively. (i.e. % coefficient of variation (RSD) ranged in between 0.52 to 3.00).
The recovered content obtained in all the dose groups was in agreement with the target concentration (i.e. ranged between 91.42 % to 104.48 % for main study and 93.95 % to 97.19 % for dose range finding study).


CONCLUSION
OXALIC ACID was mixed with diet and administered to wistar rats for a period of 90 days at doses of 250, 500 and 1000 PPM. No test item related changes in the body weights, feed consumption, haematology, clinical biochemistry, urine parameters and organ weights were noted. Macroscopic and microscopic examination revealed no abnormality attributable to the treatment at the highest dose (1000 PPM). Hence, under the conditions of the experiment and based on the findings of the present study entitled “Repeated Dose 90 Days Oral Toxicity Study with OXALIC ACID in Wistar Rats” the NOAEL (No Observed Adverse Effect Level) was found to be the highest dose level employed i.e., 1000 PPM.

No treatment related effects were observed (e.g. functional observation battery, hematology, clinical biochemistry, adrenals, and thymus). The effects observed were due to species, strain, age, biological variation, incidental, congenital and/or physiology relatedNo treatment related effects were observed (e.g. functional observation battery, hematology, clinical biochemistry, adrenals, and thymus). The effects observed were due to species, strain, age, biological variation, incidental, congenital and/or physiology related.

No Observed Adverse Effect Level (NOAEL) – 1000 ppm. This value corresponds to 63 mg/kg bw/d, according to calculations accordig the formula: RFC (Relative Feed Consumption) = AFC/7 + [bw start of week 1 + bw gain during week/2]

1000 ppm corresponds to 50 mg/kg if you apply 0.05 factor. However this is applicable for more than 13 weeks study not for the below or up to 13 week study.
63 mg/kg of test item calculate using the above formula based on the actual amount feed consumed and bodyweight gain of animals. Hence there will be difference while calculating with factor and actual values obtained in the study.