Phthalic acid

Phthalic acid is used mainly in the form of the anhydride to produce other chemicals

such as dyes, perfumes, saccharin, phthalates and many others. According to the

Directive 67/548/EEC, this chemical is not classified. Nevertheless in one of the

available MSDS related to phthalic acid, irritant to the eyes, respiratory or skin

classification with the risk phrases (R36, R37 and R38) were found. Its PBT status is

unknown. An assessment of the PBT status of Phthalic acid using the algorithm

described in the toolbox is explained below step by step.

Step1: Substance identification

Identifiers on phthalic acid have been obtained from the most recent reliable sources

(www.chemfinder.com and chemID plus) which are listed in step1. The smiles

notation for phthalic acid was obtained from both chemspider and chemIDplus

sources. These identifiers are shown in Table1 below.

Identifier of Phthalic acid

EINECS or ELINCS number 201-873-2

CAS name and CAS number 88-99-3

Name(s) in the IUPAC nomenclature orother international chemical name(s)

1,2-Benzenedicarboxylic acid

Other names (usual name, trade name,abbreviation)

o-benzenedicarboxylic acid; o-Dicarboxybenzene; o-Phthalic Acid;benzene-1,2-dicarboxylic acid; Phthalic acid;sunftal 20

Information related to molecular andstructural formula of Phthalic acidMolecular Formula C8H6O4

Structural formula OHOO

OH

Smiles Notation O=C(O)c1ccccc1C(=O)O

Table1: Phthalic acid identification parameters.

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Step 2: Data needed for the assessment

These are divided into the followings:

Physical-chemical properties (water solubility, Partition coefficient n-

octanol/water, Soil Adsorption Coefficient (Koc/Kd), and Henry's Law

Constant)

Degradation, (biodegradation, half lives)

Accumulation (BCF)

Environmental Partitioning (MacKay)

Ecotoxicity data of the substance (LC50, NOEC)

Step3: Collecting the available information and identifying the data gap

1- Information on the physical-chemical properties for Phthalic acid

The following table provides a summary of the

1. Chemical and physical properties required for the assessment as explained in

the algorithm.

2. The available chemical and physical properties of Phthalic acid along with the

source for these data. As explained in the algorithm, in this step you have to

make sure that the data studies were conducted according to EU-approved

methods (e.g. those specified in Annexes V and VIII of Directive 67/548/EEC,

or REACH Annex X methods) and in compliance with the principles of GLP.

This only applies for degradation, accumulation and ecotoxicity studies not for

the physical-chemical one. No IUCLID found for phthalic acid.

3. The data gap which is highlighted as red in the table.

Required Property Value Source

Water solubility 7010 mg/l at 25°<0.1 g/100 mL at 20 C

ChemIDplus-Chemfinder

Partition coefficient n-octanol/water

Log Kow = 0.73 (EXP) ChemIDplus

Soil AdsorptionCoefficient (Koc/Kd)

The Koc values were determinedfor an acidic forest soil (Podzol,4.85% organic carbon, pH 2.8), anagricultural soil (Alfisol, 1.25%organic carbon, pH 6.7) and a

Von Oepen B et al;Chemosphere 22: 285-304(1991)

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sublimnic soil (sediment fromLake Constance, Germany, 1.58%organic carbon, pH 7.1) as 31, 2and 2, respectively. According toa classification scheme(2), theseKoc values suggest that phthalicacid is expected to have very highmobility in soil.

Henry's Law Constant No experimentally determinedHenry’s law constant informationis available only calculated.2.18E-12 atm m3/mol (EST)

Table2: Physical chemical data available for Phthalic acid.

2- Accumulation data of Phthalic acid

According to HSDB result (Hazardous substances data bank, this can be accessed via

Toxnet), bioaccumulation of phthalic acid was studied in crops. The study showed

that the potential of phthalic to accumulate in crops is rather low. In addition, an

estimated BCF of 3 was reported for phthalic acid in this report. These values are

considered to give sufficient evidence on a very low bioaccumulation of Phthalic acid.

3- Degradation data of Phthalic acid

The following table provides a summary of the

1. Degradation properties required for the assessment as explained in the

algorithm.

2. The available degradation data of Phthalic acid along with the source for these

data. As explained in the algorithm, the data should be reliable.

3. The data gap which is highlighted as red in the table.

Required Property Value Source

Biodegradation On the basis of the available data,Phthalic acid is considered to bereadily biodegradable under bothaerobic and anaerobic conditions.(study conducted according toOECD TG 301C guideline)

HSDB (references of thestudies are listed in thereport)

Half lives-t1/2

1-Hydrolysis as afunction of Ph

No experimental aquaticdegradation data are available forPhthalic acid.

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2-Photolysis(Atmospheric OH RateConstant)

No experimental data areavailable for Phthalic acid onlycalculated oneRate Cons = 1.24E-12cm3/molecule-secc

ChemIDplus andHSDB

Table3: Degradation data available for Phthalic acid.

4- Environmental Partitioning (MacKay)

No data found.

5- Aquatic toxicity information of Phthalic acid

The results of ecotoxicity tests carried out with Phthalic acid on fish and other

specious have been cited in the ECOTOX database:

http://cfpub.epa.gov/ecotox/quick_query.htm. The data are summarised below in

Table 4.

Required Property Value Source

FishAcute toxicity to fish (96hrs LC50)mg/l

LC50(48h) > 1000000 ug/L ECOTOX

Long term toxicity to fish (28daysNOEC) mg/l

No data available

DaphniaAcute toxicity to Daphnia (48hrsEC50) mg/l

No data available

Long term toxicity to Daphnia(21days NOEC) mg/l

No data available

AlgaeAcute toxicity to algae (72hrsEC50) mg/l

No data available

Table4: Aquatic toxicity data available for Phthalic acid.

Step 4: Filling the data gap by using QSAR

In this step the above endpoints (both the available and not) will be predicted using

QSARs tools and software listed in step 4 of the algorithm (EPIWIN, Danish(Q)SAR

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data base and PBT profiler). The reason for doing this is to compare the QSAR results

with the experimental one to identify the accuracy of the QSAR.

1- Results obtained by using EPIWIN

Table 5 provides the predicted values for the above endpoints using EPIWIN software

along with the name of the programme used. The output obtained by EPIWIN for

each end point is given. Also included are explanations which could be obtained by

clicking on a link to view.

Required Property EPI QSARProgramme

Predicted Value

Water solubility WSKOW(result output)

1.524*104 mg/l at 25 C

Partition coefficient n-octanol/water

KOWWIN Log Kow = 1.07

Bioconcentration Factor (BCF) BCFWIN LogBCF = 0.5 (BCF = 3.5)

Soil Adsorption Coefficient(Koc/Kd)

(PCKOCWIN) Koc = 73

Henry's Law Constant HENRYWIN 2.18 * 10-12atm-m3/mole

Half lives-t1/2

1-Hydrolysis as a function of pH HYDROWIN Can not be estimated

2-Photolysis (Atmospheric OHRate Constant)

AOPWIN Atmospheric Oxidation

Rate Constant = 1.24E-12 cm3/molecule-sec

Half-Life = 104 hrs

( Atmosph. Oxidation, Ozone) AOPWIN No Ozone Reaction Estimation

Biodegradability

BIOWIN1 BIOWIN 1.02 (Biodegrades fast)

BIOWIN2 BIOWIN 0.99 (biodegrades fast)

BIOWIN3 (Ultimatebiodegradation)

BIOWIN 3.01(weeks)

BIOWIN4 (PrimaryBiodegradation)

BIOWIN 3.62 (weeks)

BIOWIN5 BIOWIN 1.00 (Biodegrades fast)

BIOWIN6 BIOWIN 0.96(Biodegrades fast)

BIOWIN7 BIOWIN 0.99 (Biodegrades fast)

Ready Biodegradability Prediction:BIOWIN YES

Environmental Partitioning

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(MacKay) EPI V3.2(Results output)

Level III Fugacity Model:Mass Amount Half-Life

(percent) (hr)Air 9.9e-006 208Water 36.4 360Soil 63.5 720Sediment 0.07 3.24e+003

FishAcute toxicity to fish (96hrs LC50)mol/lLong term toxicity (28days NOEC)mol/l

ECOSAR LC50 (96hrs) = 9218.48mg/l (not reliable becauseChemical may not be soluble enough to measure this

predicted effect)LC50(14 days) = 14404mg/l (not reliable because Chemicalmay not be soluble enough to measure this predicted

effect)

ChV(30days)= 1022 mg/l, where CHV is chronic toxicityvalue

DaphniaAcute toxicity to Daphnia (48hrsEC50) mol/lLong term toxicity (21days NOEC)mol/l

ECOSAR LC50 (48hrs) = 9263.168 mg/l (not reliable becauseChemical may not be soluble enough to measure this

predicted effect)

EC50(16-day)= 316.271 mg/l

AlgaeAcute toxicity to Algae (72hrsEC50) mol/l

ECOSAR EC50 (96-hr) = 5489.205 mg/l

ChV(96hrs) = 320.686mg/l

Table5: EPIWIN predictions of the required endpoints

2- Results obtained from (Q)SAR database

Unfortunately, no data was found for Phthalic acid using the Danish(Q)SAR database.

The search revealed reports for similar compounds such as Phthalic ammonium salt

and phthalic acid diethyl ester. However other QSAR databases could be used such as

chemspider or PBT profiler. The PBT profiler report for Phthalic acid is shown below

(Figures 1 and 2) with some comments. This output contains predictions for some

physical-chemical and environmental endpoints which are highlighted in yellow in the

report. These values have been predicted in the PBT profiler using the EPIWIN suite

and therefore we can check whether the results obtained directly with the EPIWIN

suite agree (Table 6).

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Figure1: PBT profiler data entry output for Phthalic acid.

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Figure2: PBT profiler data entry output for phthalic acid.

Before proceeding to step 5, it is useful to compare the predicted values obtained from

EPIWIN and the PBT profiler with the experimental data (see Table 6). As well as

checking the accuracy of the methodology, the reproducibility of EPIWIN predictions

can be tested as explained previously.

From Table 6 we could see that the available QSAR-prediction is in line with the

experimental result. For example the calculated log Kow is 1.07 while the measured

one is 0.73. Moreover, the predictions from the EPIWIN suite are consistent with the

one obtained from the PBT profiler (Log Kow, Log Koc and Henry's Law Constant, see

Table 6).

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Required Property Predicted Value using PBTprofiler

Predicted Value using EPIWIN Experimental orfound Value

Water solubility 15000mg/l 1.524*104 mg/l at 25 C 7010 mg/l at 25°

Partition coefficient n-octanol/water

log Kow = 0.73 (EXP) Log Kow = 1.07 Log Kow = 0.73(EXP)

Bioconcentration Factor(BCF)

BCF = 3.2 LogBCF = 0.5 (BCF = 3.5) 3

Soil AdsorptionCoefficient (Koc/Kd)

log Koc = 3.846 Koc = 73 31, 2 and 2,

Henry's Law Constant 2.18 * 10-12atm-m3/mole 2.18 * 10-12atm-m3/mole 2.18E-12 atmm3/mol

Half lives-t1/2

1-Hydrolysis as a functionof Ph

N/A Can not be estimated No measured dataare available.

2-Photolysis (AtmosphericOH Rate Constant)

Rate Constant = 1.24E-12cm3/molecule-sec

Atmospheric Oxidation

Rate Constant = 1.24E-12cm3/molecule-sec

Half-Life = 104 hrs

= 1.24E-12cm3/molecule-secc

( Atmosph.Oxidation, Ozone)

N/A No Ozone Reaction Estimation No measured dataare available.

Biodegradability

BIOWIN1 1.02 (Biodegrades fast)

BIOWIN2 0.99 (biodegrades fast)

BIOWIN3 (Ultimatebiodegradation)

3.01(weeks) 3.01(weeks)

BIOWIN4 (PrimaryBiodegradation)

3.62 (weeks)

BIOWIN5 1.00 (Biodegrades fast)

BIOWIN6 0.96(Biodegrades fast)

BIOWIN (ReadyBiodegradabilityPrediction)

YES Biodegrades fast

EnvironmentalPartitioning

(MacKay, (III)) Mass Amount Half-Life(percent) (hr)

Air 0 208Water 36 360Soil 64 720Sediment 0

3.24e+003

Level III Fugacity Model:Mass Amount Half-Life

(percent) (hr)Air 9.9e-006 208Water 36.4 360Soil 63.5 720Sediment 0.07

3.24e+003

No measured dataare available.

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FishAcute toxicity to fish(96hrs LC50) mol/lLong term toxicity (28daysNOEC) mol/l

ChV(30days) = 1000mg/l LC50 (96hrs) = 9218.48mg/l (notreliable because Chemical may notbe soluble enough to measure this

predicted effect)LC50(14 days) = 14404mg/l (notreliable because Chemical may notbe soluble enough to measure this

predicted effect)

ChV(30days)= 1022 mg/l, whereCHV is chronic toxicity value

LC50(48h) >1000000 ug/L.

DaphniaAcute toxicity to Daphnia(48hrs EC50) mol/lLong term toxicity (21daysNOEC) mol/l

LC50 (48hrs) = 9263.168 mg/l (notreliable because Chemical may notbe soluble enough to measure this

predicted effect)

EC50(16-day)= 316.271 mg/l

No measured dataare available.

AlgaeAcute toxicity to Daphnia(72hrs EC50) mol/l

EC50 (96-hr) = 5489.205 mg/l

ChV(96hrs) = 320.686mg/l

No measured dataare available.

Table6: Comparison between the results obtained from EPIWIN, PBT profiler andthe experimental one.

Step 5: Assess your substance to identify whether it is PBT or vPvB

Is your substance persistent? (Degradation properties)

The assessment of persistence is based on the degradation (biotic and chemical) and

half life data. As seen above, no measured data are available on the rate of

degradation of Phthalic acid in the environment. Where no measured environmental

degradation data are available, the predicted one can be used as a screen to indicate

persistence.

The predicted rate constant and estimated half-life for the reaction of hydroxyl

radicals with Phthalic acid in the atmosphere indicated that when Phthalic acid is

released to the atmosphere is likely to be degraded (not persistence) by this fate

process. Moreover the PBT Profiler has estimated that Phthalic acid is expected to be

found predominantly in soil and its persistence estimate is based on its transformation

in this medium. Its half-life in soil, 30 days, does not exceed the EU criteria of 120

days). As expected, this result is similar to EPIWIN v3.2 estimate for Level III

Fugacity Model (since PBT profile uses EPIWINV3.2 for this). Therefore, Phthalic

acid is estimated not to be persistent in the environment.

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With regard to the biotic degradation assessment, the ready biodegradability result can

be used to determine if a substance meets the P criteria. Based on the

biodegradability screening tests available (HSDB), Phthalic acid is considered to be

readily biodegradable under both aerobic and anaerobic conditions. Moreover, the

BIOWIN v4.02 gives an overall prediction that the substance is readily

biodegradable.

As a conclusion, based on the degradation and half life data (measured or estimated

by PBT profile and EPIWIN), Phthalic acid is not considered to meet the screening

criteria for persistence.

Is your substance bioaccumlative?

No measured BCF data are available. The potential for bioaccumulation was therefore

assessed on the basis of a calculated BCF.

BCFWIN v2.17 predicts BCF of 5 (<2000) based on logKow of 0.73. Moreover, BCF

estimate from PBT profiler is also in consistent with BIOWIN.

Based on the above estimates, Phthalic acid is not expected to bioaccumulate in the

food chain and therefore is not considered to meet the screening criteria for

bioaccumulation.

Is your substance toxic to the environment organisms?

The ecotoxicity data cited in the ECOTOX database for Phthalic acid are clearly

above 0.1mg/l. Although is not clear if these studies were conducted according to EU-

approved methods but their values are considered to give sufficient evidence on a low

toxicity of Phthalic acid. Furthermore, QSARs predict acute L(E)C50 values for fish

and Daphnia (LC50(96h) of 9218.48 mg/l for fish and LC50(48hrs) of 9263.168 mg/l

for Daphnia). However, these acute toxicity predictions are not reliable as chemical

may not be soluble enough to measure this predicted effect. Only the chronic toxicity

data for Daphnia (EC50(16-day)= 316.271 mg/l, CHV(30days = 1022mg/l ) and acute

toxicity for Algea (EC50 (96-hr) = 320.686 mg/l ) can be considered. These values

are clearly far above 0.1mg/l. It is therefore considered reasonably to conclude that

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the EU criteria for toxicity are not met. This is in consistent with PBT profiler

ecotoxicity estimate for Phthalic acid.

In conclusion, in the absence of reliable toxicity data, Phthalic acid is not considered

fulfilling the T screening criterion based on the QSAR predictions.

Is your chemical classified as potential PBT?

Based on the predictions data, the substance has been shown to be readily

biodegradable and not persistent. In addition, both the estimated and measured BCF

for the substance in fish are far below 2000. Therefore the substance does not fulfil

the B-criterion. The estimated aquatic toxicity data for Phthalic acid are clearly above

0.1mg/l, therefore the substance does not fulfil the T-criterion.

Therefore on the basis of the predictions data the substance should not be considered

as a potential PBT substance.

What is the preferred environmental compartment of your chemical?

(Environmental Distribution )

Adsorption:

According to Mackay level III predictions the soil is the preferred environmental

compartment (64%) for Phthalic acid. As the substance has a low Koc value of 2 and

31 when it is released to soil, phthalic acid is expected to have very high mobility.

Moreover, if phthalic acid is released into water, it is not expected to adsorb to

suspended solids and sediment based upon the Kocs. Therefore the persistence of

Phthalic acid in soil is probably not so significant.

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