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EC number: 202-908-4
CAS number: 101-02-0
In attempting to design appropriate studies to investigate the acute
ecotoxicity of TPP in algae, daphnids and fish, it was discovered that
the testing would be difficult to conduct in compliance with OECD
Guidance Document #23 entitled “Guidance Document on Aquatic Toxicity
Testing of Difficult Substances and Mixtures” (OECD 2000) because of the
inherent physical/chemical properties of the test substance (i.e.,
extremely poor water solubility and rapid hydrolysis at the calculated
limit of solubility). After consultation with experts, it was concluded
that, since direct measurements of the ecotoxicity of the parent test
substance would likely be very difficult the testing program should
focus on quantifying the toxicity of the combination of hydrolysis
by-products of "aged" TPP.
Measured and calculated aquatic toxicity values (EC50)
for the individual primary hydrolysis by-products of TPP (phenol and
phosphorous acid) were identified. With these data, estimates of the
acute ecotoxicity values (solution toxicity values) based on the sum of
the ratios of the maximum theoretical concentration of the individual
hydrolysis by-products (i.e., “aged” TPP) in solution (at the limit of
solubility) and their representative ecotoxicity values (EC50)
were found to be 2.2 x 10-3(algae), 2.7 x 10-2(daphnids)
and 3.1 x 10-2(fish). Since a derived solution toxicity
value of 1.0 is considered to be equivalent to anEC50for
the “aged” solutions, the further below a value is from 1 the lower the
inferred ecotoxicity hazard. On this basis, these findings indicate that
the mixture of hydrolysis by-products arising from a standard solution
of TPP would not be toxic to aquatic organisms.
It is possible to quantitatively predict the maximum theoretical
concentration of hydrolysis by-products and resulting toxicity of the
solution of these by-product based on the known toxicity of the
individual by-products, assuming additive toxicity.
On this basis, a detailed literature search was conducted to assess the
available database of information pertaining to the acute toxicity of
phenol and phosphorous acid to fish (rainbow trout), daphnids and algae.
Where sufficient data were unavailable in the scientific literature,
ECOSAR (US EPA 2001) was used to model the potential ecotoxicity of the
hydrolysis by-products of TPP. A summary of the acute
ecotoxicity data for these byproducts to these organisms is provided in
By this method, a solution toxicity value of 1.0 is considered
equivalent to an acute EC50value (i.e.,itwould
predict 50% acute mortality /growth inhibition in the test species,
based on the theoretical concentrations).
Based on the following stoichiometry:
one mole TPP (mw= 310.29 g/mole) yields three moles phenol (mw = 94.11
g/mole) and one mole phosphorous acid (mw= 82.00 g/mole);
At its aqueous solubility limit of 0.3 mg/L, TPP would hydrolyse to 2.9
x 10-6moles/L phenol and 9.7 x 10-7moles/L
phosphorous acid. These molar concentrations equate to mass
concentrations of 0.27 mg phenol/L and 0.079 mg phosphorous acid/L
The modeling results of the solution toxicity values for the mixture of
hydrolysis by-products of TPP at its aqueous solubility limit in fish,
daphnids and algae are summarized below.
The predicted solution toxicity values attributable to the mixture of
TPP hydrolysis by-products were calculated to be2.2 x 10-3(algae),
2.7 x 10-2(daphnids) and 3.1 x 10-2(fish).
These values are well below 1.0 indicating that the mixture of
hydrolysis by-products arising from a saturated solution of TPP would
essentially be not toxic to aquatic organisms. While a classification of
R50 -53 was established for TPP, there is no clear basis for this
classification and due to the rapid hydrolysis of TPP it is simply not
possible to test its aquatic toxicity reliability. The hydrolysis
products for TPP, phenol and phosphorous acid, are not classified as
dangerous to the environment, further supporting the conclusion that TPP
will not be toxic to aquatic organism.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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