Registration Dossier

Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No OECD guideline or GLP defined.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1997

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
other: Developmental toxicity study in rats.
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test substance Phthalic Acid (PA) (99.5% pure, Aldrich, Milwaukee, WI).

Test animals

Species:
rat
Strain:
Wistar Kyoto (WKY)

Administration / exposure

Route of administration:
oral: feed
Vehicle:
other: diet
Details on exposure:
The pregnant rats were fed a diet containing PA (99.5% pure, Aldrich, Miwaukee, WI) at a dose of 1.25, 2.5, or 5.0% ad libitum on day 7 through to day 16 of pregnancy.
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
Virgin female rats , about 12 weeks old, were mated overnight with male rats. The day when sperm were detected in the vaginal smear was considered to be day 0 of pregnancy. The pregnant rats were distributed on a random basis into four groups of 11 pregnant rats each housed individually.
Duration of treatment / exposure:
The pregnant rats were fed a diet ad libitum on day 7 through to day 16 of pregnancy.
Frequency of treatment:
daily
Duration of test:
The pregnant rats were sacrified on day 20 of pregnancy.
Doses / concentrations
Remarks:
Doses / Concentrations:
1.25, 2.5, 5.0% PA. The average daily intake of the test substance was 1021, 1763, or 2981 mg/kg/day
Basis:

No. of animals per sex per dose:
11
Control animals:
yes

Results and discussion

Results: maternal animals

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Remarks:
MTD
Effect level:
ca. 1 021 mg/kg bw/day (nominal)
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
ca. 1 763 mg/kg bw/day (nominal)
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Maternal findings in rats given dietary PA on days 7 -16 of pregnancy:

            PA (%)
   0 (control)  1.25  2.5  5.0
 No. of pregnant rats  11  11  11  11
 No. of dead pregnant rats  0  0  0  0
 Initial body weight (g)  242+10 243+16   243+12  244+16
 Body weight gain during pregnancya)        
 Days 0 -7  24+6  26+10  31+6  27+7
 Days 7 -16  49+8  54+8  40+5*  20+12**
 Days 16 -20  41+9  40+8  47+11  57+16**
 adjusted weight gainb)  50+11  47+10  42+10  30+12**
 Food consumption during pregnancy (g)a)        
 Days 0 -7  138+8  140+15  145+13  138+8
 Days 7 -16  198+11  197+10  173+17**  145+13**
 Days 16 -20  88+10  98+4**  101+6**  120+7**
 Daily intake of PA (mg/kg)a,c)  0  1021+52  1763+163  2981+270

a)Values are given as mean+S.D:

b)Adjusted weight gain refers to maternal weight gain excluding the gravid uterus.

c)[Food consumotion on days 7 -16/9)x%PA]/body weight on day 7.

*,**Significantly different from the control, P<0.05 and P<0.0.1, respectively.

Reproductive findings in rats given dietary PA on days 7 -16 of pregnancy:

            PA (%)
   0 (control)  1.25 2.5  5.0
 No. of litters  11  11  11  11
 No. of corpora lutea per littera)  14.3 +1.3  15.3 +1.6  15.7 +2.3  15.7 +1.5
 No. of implantations per littera)  13.1 +2.1  14.0 +1.7  14.3 +3.3  13.8 +3.4
 No. of litters totally resorbed  0  0  0  0
 No. of resorbtions and dead fetuses per littera)  1.6 +1.6 1.3 +1.1   0.9 +1.0  1.3 +1.4
 % Postimplantation loss per litterb)  14.2  9.3  5.8  8.7
 No. of live fetuses per littera)  11.5 +3.0  12.7 +2.2  13.4 +3.0  12.5 +3.4
 Sex ratio of live fetuses (male/female)  60/66  61/79  83/64  62/76
 Body weight of live fetuses (g)a)        
 Male  4.19 +0.13  4.15 +0.07  4.20 +0.18  4.03 +0.18*
 Female  3.92 +0.16  3.95 +0.13  3.92 +0.15  3.82 +0.14

a) values are given as mean + S.D.

b) (No. of resorbtions and dead fetuses/no. of implantations)x100.

* Significantly different from the control, P<0.05.

Morphological findings in fetuses of rats given dietary PA on days 7 -16 of pregnancy:

            PA (%)
   0 (control)  1.25  2.5  5.0
 external examination      
  No. of fetuses (litters) examined  126 (11) 140 (11)  147 (11)  138 (11)
  No. of fetuses (litters) with malformations  0  0  0  0
 Skeletal examination        
    No. of fetuses (litters) examined  84 (11)  94 (11)  97 (11)  92 (11)
    No. of fetuses (litters) with malformations  0  0  0
    No. of fetuses (litters) with variations  4 (3)  5 (4)  4 (3)  10 (6)
    No. of fetuses (litters) with:        
  Splitting of thoracic vertebral bodies  1 (1)  0  0  0
  Asymetric of sternebrae  3 (3)  4 (3)  4 (3)  7 (6)
  Splitting of sternebrae  0  1 (1)  0 5 (3) 
  Degree of ossification        
  No. of ossification centers of caudal vertebraea)  5.5 +0.3  5.3 +0.3  5.4 +0.3  5.1 +0.2*
  No. of sternebraea)  5.9 +0.1  6.0 +0  6.0 +0.1  5.9 +0.1
 Internal examination        
  No. of fetuses (litters) examined  42 (11)  46 (11)  50 (11)  46 (11)
    No. of fetuses (litters) with malformations  0  0  0  0

a) Values are given as mean +S.D.

* Significantly different from the control, P<0.01.

Applicant's summary and conclusion

Executive summary:

The developmental toxicity of phthalic acid was investigated in a developmental toxicity study. Groups of eleven pregnant Wistar rats were fed a diet containing phthalic acid at a dose of 0, 1.25, 2.5, or 5.0 % ad libitum on GD 7 - GD 16 ( 0, 1021, 1763, 2981 mg/kg bw/day). The administration in the feed was selected because of only slight solubility of phthalic acid in water and oil. The pregnant rats were observed daily for evidence of clinical signs of toxicity, maternal body weight and food consumption. Average daily intake of phthalic acid was calculated. The pregnant rats were sacrificed on day 20 of pregnancy. The peritoneal cavity and uterus were opened and the numbers of live and dead fetuses and resorptions were counted. The gravid uterus was removed and the rats weighed again. The adjusted weight gain, i.e. maternal weight gain throughout pregnancy corrected for gravid uterine weight, was calculated. The live fetuses removed from the uterus were sexed, weighed and inspected for external malformations and malformations within the oral cavity. Approximately two-thirds of live fetuses in each litter, randomly selected, were stained with alizarin red S and examined for skeletal malformations. The remaining live fetuses in each litter were fixed in Bouin¿s solution and examined for internal malformations. Maternal toxicity occurred in the 2.5 and 5.0 % groups as demonstrated by decreases in the adjusted maternal bodyweight gain (maternal bw gain excluding the gravid uterus; 30, 42, or 50 g for the 5, 2.5, or control group, respectively) during the administration period. No significant changes in maternal parameters were found in the 1.25 % group (adjusted body weight gain 47 g). No deaths or clinical signs of toxicity were noted in any group. No significant changes induced by phthalic acid were detected in the incidence of postimplantation loss, number and sex ratio of live fetuses. Significant decreases in the weight of male fetuses and decreased numbers of ossified centers of the caudal vertebrae were found only in the 5.0 % group, where significant maternal toxicity also was observed. Morphological examinations of fetuses revealed no evidence of developmental toxicity (NOAEL, maternal toxicity: 1.25 % in feed = 1021 mg/kg bw/day; NOAEL, developmental toxicity: 2.5 % in feed = 1763 mg/kg bw/day).