Diisobutylphthalate (DIBP) (Feb 1997)
Anonymous
| HERO ID | 1312353 |
|---|---|
| Year | 1998 |
| Title | Diisobutylphthalate (DIBP) (Feb 1997) |
| Authors | Anonymous |
| Volume | BUA |
| Abstract | Degradability. DIBP released into the troposphere is photochemically-oxidatively degraded by OH-radicals with a half-life of cat 40 hours. An increase of the atmospheric half-life is expected through the presence of DIBP bound to particles. A direct photolysis is not expected in air and water. The hydrolytic degradation is practically of no importance under environmental conditions. According to existing laboratory studies, DIBP is characterized as being "readily biodegradable" under aerobic conditions. However, the degradation apparently stops at concentrations in an order of magnitude of cat 20-100 ng/l. Accumulation. On hand of the n-octanol/water partition coefficient (log Pow = 4.11) and the bioconcentration factor (BCF = 780) estimated from it, a definite tendency towards bioaccumulation is expected which, however, is not confirmed by recently completed experimental studies of H?ls AG. No information is available about geoaccumulation. However, a soil sorption coefficient value of Koc = 4,100 can be estimated from the n-octanol/water partition coefficient (log Pow = 4.11). According to Blume and Ahlsdorf there is a high tendency towards soil sorption, however, in field tests the potential for accumulation in soils with repeated deposition of sewage sludge was shown to be low. A transport with leachate into groundwater is expected through complex formation, e.g with humic acids. Ecotoxicology. Because a surface adsorption of DIBP in aquatic systems cannot be excluded, a differentiation between nominal and effective concentrations has been made below. In the oxygen consumption test, DIBP in concentrations (nominal) of up to 1.7 mg/l showed no inhibiting effect on microorganisms. In a cell-multiplication inhibition test with the green algae Scenedesmus subspicatus, ECso values (effective concentrations) of 1.0 mg/l (biomass) and 2.2 mg/1 (growth rate) were determined. The 24 h EC50 value for the water flea Daphnia magna and the 96 h EC50 value for the crustacean Nitocra spinipes were 7.4 and 3.0 mg/l, respectively (nominal concentrations). In a 21-day reproduction test with the water flea Daphnia magna, a NOEC of 1.0 mg/l (nominal concentration) was determined based on the mortality of the parent animals and the reproduction. Regarding the toxicity of DIBP in fish, a 96 h LC50 value of 0.9 mg/l (flowthrough test, effective concentration) and a 48 h LC50 value of 4.2 mg/l (static test, nominal concentration) were determined for the fathead minnow (Pimephales promelas) and the golden orfe (Leuciscus idus). At DIBP concentrations of 160-180 ng/l air, a definite toxic effect was found in certain plants (e.g. cruciferous plants), while others were less sensitive or not at all. Toxicological Aspects. Phthalates are readily taken up via all exposure routes and are quickly distributed throughout the organism. Excretion takes place in the urine and faeces, and there is no tendency towards accumulation. Phthalates are not acutely toxic. The lowest LD50 values for rats and mice are 15,000 and 13,000 mg DIBP/kg b.w., respectively. LD50 values for rats and mice following i.p. injection lie in the range of= 1,600 mg DIBP/kg b.w. The dermal LD50 value for guinea pigs is 10,000 mg DIBP/kg b.w. The inhalative exposure (8 hours) of rats to DlBP-saturated air did not cause any deaths. DIBP irritates neither the eyes nor skin of rabbits. No data are available on the skin sensitizing effect of DIBP. In a short-term oral toxicity study (14 days) with female rats, a NOEL of 50 mg DIBP/kg b.w. is specified on the basis of increased liver weights, altered clinical-chemical parameters (serum albumin, cholesterol- and triglyceride values) as well as peroxisome proliferation in hepatic tissue (increase of biochemical parameters). For rats, other NOELs in the range of 50-75 mg DIBP/kg b.w. are described afler oral administration (up to 4 months). Analogous to other phthalates (BUA Reports No. 4, 22, 114), DIBP acts hepatotoxic in the sense of a peroxisome proliferation. The projection of this rodent-specific mode of action to humans is questionable. In vitro mutagenicity studies with various S. typhimurium strains showed no indication of a genotoxic effect. The available studies on reproductive toxicity allow neither a clear evaluation of the fertility-impairing potential nor the specification of NOAELs. By considering the effect of structure-related phthalates (BUA Reports No. 4, 22, 114), a hazard potential, in the sense of fertility impairment or embryonal damage in a non-maternally toxic concentration range, cannot be excluded. Studies on carcinogenicity are not available. However, long-term studies with other phthalates show that they trigger tumors mainly via the mechanism of peroxisome proliferation. |
| Report Number | RISKLINE/1997090023 |
| Is Certified Translation | No |
| Dupe Override | No |
| Comments | Journal: Beratergremium fuer umweltrelevante Altstoffe ISSN: |
| Is Public | Yes |
| Language Text | eng |
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