Dibutyl phosphate

リン酸ジブチル

CAS No. 107-66-4

Dibutyl hydrogen phosphate / Phosphoric acid dibutyl ester

リン酸ジブチルエステル

Molecular formula: C8H19O4P Molecular weight: 210.24

ABSTRACT

The single dose oral toxicity test resulted in an LD50 of more than 2000 mg/kg for both sexes.

With regard to repeat dose toxicity, histopathological examination showed epithelial hyperplasia accompanied by degeneration and ulceration in the urinary bladder mucosa of males and females that received 100 mg/kg or more. Epithelial hyperplasia and hyperkeratosis of the forestomach were also noted in both sexes that received 300 mg/kg or more. Some animals demonstrated erosion or ulceration in the gastric mucosa involving both glandular and nonglandular portions. Additional signs of toxicity, such as increases in absolute and relative weights of the liver, hepatocellular swelling evident histopathologically, and a depression of weight gain were observed in both sexes that received 1000 mg/kg, as well as fatalities in males. The NOEL for repeat dose toxicity is considered to be 30 mg/kg/day in both sexes. In terms of reproductive/developmental toxicity, the number of live pups and the viability index on day 4 of lactation decreased with 1000 mg/kg. NOELs for reproductive performance are considered to be 1000 mg/kg/day for both sexes, and 300 mg/kg/day for offspring development.

Dibutylphosphate was not mutagenic in Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2 uvrA. Neither structural nor numerical chromosomal aberrations were induced in CHL/IU cells up to the concentration going 50% cell growth inhibition, in the absence or presence of an exogenous metabolic activation system.

SUMMARIZED DATA FROM THE STUDIES

1. Single Dose Oral Toxicity 1)

Purity	:	62.6% (other contents : monoester, 18.3% ; triester and others,19.1%)
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	OECD Guideline 401
Dosage	:	2000 mg/kg
Number of animals	:	Male, 5 ; female, 5/group
GLP	:	Yes

　Test results:

During the course of the study, a decrease in locomotor activity, deep and slow respiration, blepharoptosis and blotted fur with urine on the lower abdomen were observed in males and females, and lacrimation and red urine were additionally observed in some rats. Body weight gain was slightly suppressed on the following day of treatment in many rats. However, no deaths occurred, and no macroscopic abnormalities were seen in pathological examination for both male and female groups.

LD50: Male and female, >2000 mg/kg

2. Repeat Dose and Reproductive/Developmental Toxicity 1)

Purity	:	62.6% (other contents : monoester, 18.3% ; triester and others,19.1%)
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	OECD Combined Repeat Dose and Reproductive/Developmental Toxicity Screening Test
Route	:	Oral (gavage)
Dosage	:	0 (vehicle), 30, 100, 300 and 1000 mg/kg/day
Number of animals	:	Male, 10; female, 10/group
Vehicle	:	Sesame oil
Administration period	:	Male, 44 days Female, from 14 days before mating to day 3 of lactation
Terminal kill	:	Male, day 45 Female, day 4 of lactation
GLP	:	Yes

　Test results:

<Repeat dose toxicity>

Transient red urine and a decrease in food consumption were observed during the early stage of administration in males that received 100 mg/kg or more. Body weight gain decreased in males, and three males and two females receiving 1000 mg/kg died. There were no observed effects of the test substance on urinary, hematological and blood chemical findings for the treated males. Histopathological examination showed epithelial hyperplasia accompanied by degeneration and ulceration of the urinary bladder mucosa of males and females that received 100 mg/kg or more. Epithelial hyperplasia and hyperkeratosis of the forestomach were also noted in both sexes that received 300 mg/kg or more. Some animals demonstrated erosion or ulceration in the gastric mucosa, involving glandular and nonglandular portions. Increases in absolute and relative weights of the liver were observed in females receiving 1000 mg/kg that showed hepatocellular swelling histopathologically.

The NOEL is considered to be 30 mg/kg/day for both sexes.

<Reproductive and developmental toxicity>

The parental animals exhibited no significant effects on reproductive parameters including copulation index, fertility index, numbers of corpora lutea and implantation sites, gestation index and gestation length. The number of live pups and the viability index at a dose of 1000 mg/kg decreased, attributable to a high incidence of fatalities of pups in some litters at or after birth.

NOELs for reproductive performance are considered to be 1000 mg/kg/day for both sexes, and 300 mg/kg/day for offspring development.

3. Genetic Toxicity

3-1 Bacterial test 2)

Purity	:	62.6%
Test species/strains	:	S.typhimurium TA100, TA1535, TA98, TA1537, E. coli WP2 uvrA
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Procedures	:	Plate incorporation method
Solvent	:	Acetone
Positive controls	:	-S9, AF-2 (TA100, WP2, TA98), sodium azide (TA1535) and 9-aminoacridine (TA1537) +S9, 2-aminoanthracene (all strains)
Dosage	:	0, 4.882, 9.765, 19.53, 39.06, 78.12, 156.2 μg/plate
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	3
Number of replicates	:	2
GLP	:	Yes

　Test results:

Minimum concentration of test substance at which toxicity was observed:

Toxicity was observed at the concentration of 156.2 μg/plate, with or without metabolic activation.

Genetic effects:

S. typhimurium TA100, TA1535, TA 98, TA1537

	+	?	-
with metabolic activation	[ ]	[ ]	[*]
without metabolic activation	[ ]	[ ]	[*]

E. coli WP2 uvrA

with metabolic activation	[ ]	[ ]	[*]
without metabolic activation	[ ]	[ ]	[*]

3-2. Non-bacterial in vitro test (chromosomal aberration test) 2)

Purity	:	62.6%
Type of cell used	:	Chinese hamster CHL/IU cells
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Solvent	:	Acetone
Positive controls	:	-S9, Mitomycin C +S9, Cyclophosphamide
Doses	:	-S9 (continuous treatment): 0, 0.06, 0.12, 0.24 mg/ml -S9 (short-term treatment): 0, 0.10, 0.21, 0.41 mg/ml +S9 (short-term treatment): 0, 0.14, 0.27, 0.54 mg/ml
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	2
GLP	:	Yes

　Test results:

Lowest concentration producing cytogenetic effects in vitro:

without metabolic activation (continuous treatment ): > 0.24 mg/ml

without metabolic activation (short-term treatment): > 0.41 mg/ml

with metabolic activation (short-term treatment): > 0.54 mg/ml

Genotoxic effects:

	clastogenicity			polyploidy
	+	?	-	+	?	-
with metabolic activation:	[ ]	[ ]	[*]	[ ]	[ ]	[*]
without metabolic activation:	[ ]	[ ]	[*]	[ ]	[ ]	[*]

1)	The tests were performed by the Research Institute for Animal Science in Biochemistry and Toxicology, 3-7-11, Hashimotodai, Sagamihara-shi, Kanagawa 229, Japan. Tel +81-427-62-2775 Fax +81-427-62-7979
2)	The tests were performed by the Hatano Research Institute, Food and Drug Safety Center, 729-5 Ochiai, Hadano-shi, Kanagawa 257, Japan. Tel +81-463-82-4751 Fax +81-463-82-9627