Diethyl phthalate

Endpoint summary

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:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Experimental data published in peer reviewed journal

Qualifier:

no guideline available

Principles of method if other than guideline:

Study not designed to meet a particular guideline.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Ltd., Margate, Kent UK
- Age at study initiation: Not specified
- Weight at study initiation: Not specified
- Fasting period before study: N/A
- Housing: Not specified for standard short term study; singly housed for pair feeding study
- Diet (e.g. ad libitum): yes
- Water (e.g. ad libitum): yes
- Acclimation period: Not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22
- Humidity (%): 50-60%
- Air changes (per hr): Not Specified
- Photoperiod (hrs dark / hrs light): Not specified

Route of administration:

oral: feed

Vehicle:

other: Spratts laboratory diet No.1

Details on oral exposure:

DIET PREPARATION
- Rate of preparation of diet (frequency): Not specified
- Mixing appropriate amounts with (Type of food): Not specified
- Storage temperature of food: Not specified

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

N/A

Duration of treatment / exposure:

Two, 6 and 16 weeks for standard study
16 weeks for pair feeding study

Frequency of treatment:

continuously in the diet for 2, 6 and 16 weeks

Remarks:

Doses / Concentrations:
0 (control), 0.2, 1.0 and 5.0 % for standard study and 0 (control) and 5% for pair feeding study a
Basis:
nominal in diet

No. of animals per sex per dose:

5 males and 5 females for 2 and 6 week phases
15 males and 15 females for 16 week phase
6 males and 6 females for pair feeding study

Control animals:

yes, plain diet

Details on study design:

Standard study: Groups of 15 rats of each sex were given diets containing 0 (control), 0.2, 1.0 or 5.0% DEP for 16 weeks.Additional groups of 5 rats of each sex were fed similar diets for 2 or 6 weeks. Body weight, food and water consumption consumption were measured at intervals. On completion of the designated treatment period the rats were deprived of food overnight and killed by exsanguination from the aorta under barbiturate anaesthesia. Blood samples were collected from the aorta for haematological and serum (at 16 weeks only) examination.
An autopsy was performed and macroscopic lesions were noted and selected organs weighed, sampled and the samples preserved in 10% buffered formalin. These tissues were processed to paraffin wax blocks, sectioned and stained with haematoxylin and eosin for histological examination.

Pair feeding study:
Groups of 6 rats of each sex, individually housed and fed untreated diet (controls) or diet containing 5% DEP for 16 weeks. Each control animal was from the same litter as one of the treated rats of the same sex. The treated rats were fed ad libitum and the weight consumed by each one was recorded daily. Each control rat was given a weight equal to that consumed by its paired litter mate in the previous 24 h period.Body weights were recorded at intervals during the treatment period.

Positive control:

N/A

Observations and examinations performed and frequency:

Standard short term study:
Body weight, food and water intake at weekly intervals.
Blood samples for haematological and serum (after 16 weeks only) investigation and were taken at necropsy.
Urine samples were collected for examination during weeks 2, 6 and 13.

Pair feeding study:
Food consumed daily
Body weights weekly

Sacrifice and pathology:

The rats were killed by exanguination from the aorta under barbiturate anaesthesia. Macroscopic lesions were noted and the brain, pituitary, thyroid, heart, liver, kidney, adrenal glands, spleen, gonads, stomach, small intestine and caecum (with and without it's contents) were weighed. Samples of these organs and of salivary glands, trachea, lung, aorta, lymph nodes, yhymus, urinary bladder, oesophagus, colon, rectum, pancreas, uterus or prostate and seminal vesivcles, skeletal muscle, eye, hardarian gland and sciatic nerve were preserved in 10% buffered formalin. Parafin wax sections of the tissues were stained with haematoxylin and eosin for histological examination.

Other examinations:

Heamatology parameters examined after 2, 6 or 16 weeks included: haemoglobin concentration, packed cell volume, red blood cell and total white cell counts. Differential leucocyte counts were evaluated in control and 5.0% rats on blood fims made after 2, 6 and 16 weeks of treatment. In addition marrow smears were prepared and stained but not examined as there were no effects of treatment on the other haematological parameters examined.
The serum collected at week 16 was examined for effects on SGPT, SGOT and lactic dehydrogenase.
The urine collected during weeks 2, 6 and 16 of treatment was examined for the presence of cells and other microscopic constituents and semi quantitative tests were carried out for protein, glucose, ketones, bile and blood.
A concentration test was performed using the volume and SG of urine collected over a 6 h period of water deprivation.and in a 4h period commencing after 16 h without water.
In weeks 6 and 13 a dilution test was performed by bmaking the same measurements on urine produced in a 2 h period following a 25 ml/kg water load.

Statistics:

Student's t test for haematology, urine analysis, relative organ weights
Wilcoxon Rank Test for body weight and food consumption

Clinical signs:

no effects observed

Description (incidence and severity):

Mortality not specifically mentioned

Mortality:

no mortality observed

Description (incidence):

Mortality not specifically mentioned

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Standard short term study: Throughout the treatment period both sexes given 5% DEP and female rats given 1% DEPin the diet gained significantly less weight than the controls. Transient lower body weight gains were seen in males given 1% DEP.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Overall food consumption was significantly lower than that of controls in rats of both sexes given 5% and females given 1%.

Food efficiency:

not specified

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

Slight changes, some of which attained statistical but not biological significance.

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Description (incidence and severity):

Slight changes, some of which attained statistical but not biological significance.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Increases in the absolute and relative weights of stomach and small intestine in rats of both sexes and in female rats given 0.2 and 1% DEP in the diet.

Gross pathological findings:

no effects observed

Description (incidence and severity):

Abnormalities seen in testis of 1 male rat in 0.2 mgkg/day group.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

only abnormalities commonly seen in this strain of rat

Histopathological findings: neoplastic:

not examined

Details on results:

BODY WEIGHT AND WEIGHT GAIN
Throughout the treatment period both sexes given 5% DEP and female rats given 1% DEP in the diet gained significantly less weight than the controls. Transient lower body weight gains were seen in males given 1% DEP.

FOOD CONSUMPTION AND COMPOUND INTAKE
Overall food consumption was significantly lower than that of controls in rats of both sexes given 5% and females given 1%. Total group mean intakes of DEP were 150, 770 & 3160 and 150, 750 & 3170 mg/kg/day in treated males and females respectively.

WATER CONSUMPTION AND COMPOUND INTAKE
No effects
HAEMATOLOGY
After 6 weeks of treatment the erthrocyte count in male rats given 5% DEP in the diet was significantly higher than in their control counterparts. This change was associated with a non significant increase in haemoglobin levels when compared with the relevant controls.

CLINICAL CHEMISTRY
No effects

URINALYSIS
Male rats given 5% DEP excreted significantly fewer cells than controls in week 13. After a 6 hour water deprivation period in Weeks 2 & 6 female& male rats given 5% DEP respectively produced more urine of a slightly higher SG than the controls, though this effect was not seen after the 20 hour period of deprivation.
In the 2 hour dilution test in week 6 male & female rats given 5% DEP produced significantly larger volumes of more dilute urine & smaller volumes of less dilute urine than controls. In week 13 the urine of male rats given 5% DEP had a significantly higher SG.

ORGAN WEIGHTS
In rats of both sexes given 5% DEP in the diet for 16 weeks the absolute weights of the brain, heart, spleen & kidneys were statistically significantly lower than controls. There were also reductions in the absolute weights of the gonads (females) & heart and the spleen & kidneys of males given 5% DEP in the diet after 2/6 weeks of treatment. The weights of stomach of rats given DEP at 5% in the diet increased at times during the study but attained statistical significance with respect to controls after 2 (males) and 2 & 16 (females) weeks of treatment. The weight of the full caecum was also increased in females given 5% DEP in the diet for 16 weeks.
In the 1% DEP dietary group after 2 weeks of treatment, increased kidney weights were seen in males & lower pituitary weights in females. Increased gonad weights were also seen in females after 6 weeks of treatment at the 1% dietary level.
The relative weights of the brain, kidney (week 16 only) liver, stomach, small intestine and full caecum were increased in rats of both sexes & of testes of males given 5% DEP in the diet with respect to the controls. In the rats given 0.2 or 1.0% there were similar increases in the relative weights of the liver, stomach & small intestine.

GROSS PATHOLOGY
Abnormalities seen in testis of 1 male rat in 0.2 mgkg/day group but no histological changes were seen.

HISTOPATHOLOGY: NON-NEOPLASTIC
Some fatty degeneration and slight vacuolation of the liver, pyleonephritis & lymphocytic infiltration of the kidney were observed. Incidence not dose related and all common findings of this strain of rat.

OTHER FINDINGS
None reported


Pair feeding study
CLINICAL SIGNS AND MORTALITY
Not reported
BODY WEIGHT AND WEIGHT GAIN
Rats given 5% DEP in the diet lost more weight than their respective controlsover the 1st day of treatment. Weight gain in the 5% group was also lower than in controls there after. The difference attained statistical significance in week 16.
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
The total food consumed by the rats given 5% DEP in the diet was greater than that consumed by their respective controls.
FOOD EFFICIENCY
Not reported
WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
Not reported

Dose descriptor:

NOAEL

Effect level:

150 mg/kg diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Effects on body weight and organ weight in 1.0 (750 mg/kg) and 5.0% (3160 mg/kg) dose groups

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

150 mg/kg bw/day

Study duration:

subchronic

Species:

rat

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

Dietary administration to rats for a total of 16 weeks resulted in reduced body weights in both sexes given 5% and female rats given 1% in the diet. Overall food consumption was significantly lower in rats of both sexes given 5% and females given 1%. On necropsy the absolute weights of the brain, heart, spleen and kidneys were statistically significantly lower than controls in both sexes given 5% in the diet for 16 weeks. Histopathology revealed some fatty degeneration and slight vacuolation of the liver, pyleonephritis and lymphocytic infiltration of the kidney. The incidence was not dose related and all are common findings in the strain of rat used. The NOAEL for the study was 0.2% in the diet (equivalent to 150 mg/kg bw/day) based on the observed changes in body weight/food consumption and organ weights.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Best documented study of those available

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:
Information from sub-acute studies in the rat and mouse have been reported but the level of detail erported is insufficient to meet current test guidelines.

Justification for classification or non-classification

Non-classification justified on the basis of lack of significant toxicity in a subchronic repeat dose study