Fatty acids, linseed-oil, reaction products with bisphenol A-epichlorohydrin polymer and glycidyl neodecanoate

Endpoint summary

Description of key information

There were no studies available in which the toxicokinetic properties of test substance were investigated. However, as per REACH guidance document R7. C (2014), information on absorption, distribution, metabolism and excretion may be deduced from the physicochemical properties. Based on the physicochemical properties, QSAR predictions/modelling as well as the available toxicological data, the test substance is expected to have higher absorption potential via the oral and inhalation route compared to the dermal route. It is likely to be metabolised predominantly via either oxidation at the site with OH group or ester hydrolysis. Overall, given its high lipophilicity and high MW the substance is expected to have low bioaccumulation potential.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

100

Additional information

Oral absorption

Based on physicochemical properties:

According to REACH guidance document R7.C (May 2014), oral absorption is maximal for substances with molecular weight below 500. Water-soluble substances will readily dissolve into the gastrointestinal fluids; however, absorption of hydrophilic substances via passive diffusion may be limited by the rate at which the substance partitions out of the gastrointestinal fluid. Further, absorption by passive diffusion is higher at moderate log Kow values (between -1 and 4). If signs of systemic toxicity are seen after oral administration (other than those indicative of discomfort or lack of palatability of the test substance), then absorption has occurred.

 

The test substance is a UVCB, having a relatively high molecular weight ranging from 506 to 904 g/mol. It is a liquid with low water solubility ranging from 22 to 112.7 mg/L. Volatility was determined to be low (0.0018 Pa at 25 or 0.011 Pa at 60°C) and has a very high lipophilicity with estimated log Kow of the major components exceeding >10 (using EPISuite v.4.1).

Based on the R7.C indicative criteria, oral uptake of the constituents of the test substance is assessed to be less absorbed, given their high molecular weights exceeding 500, low water solubility and high log Kow (>10) of the major constituents.

 

Based on QSAR prediction:

Human intestinal absorption (HIA) can also be predicted for the constituents of the test substance using the Multicase model v.3.45 of the OECD QSAR Toolbox v.3.4. HIA is expressed as a percentage of the oral dose absorbed from the gastrointestinal tract. Substances with HIA values of 80% are considered as well absorbed and with 90% values are extensively and almost completely absorbed. For those compounds for which the absorption was reported as being poor, the value is 5%. The estimated HIA values for the major constituents of the test substance were as follows:

-         Neodecanoic acid oxiranylmethyl ester + 1 linseed oil:90.9%

-         BADGE + 2 linseed oil and derivatives: 65.7%

Based on the above data, the individual constituents of the test substance are expected to be absorbed through the oral route.

 

Conclusion: Overall, based on all the available weight of evidence, the test substance can be overall expected to have low to moderate absorption through the oral route. Therefore, a default value of 50% has been considered for the risk assessment.

Dermal absorption

Based on physicochemical properties:

According to REACH guidance document R7.C (May 2014), dermal absorption is maximal for substances with molecular weight below 500 and log Kow values ranging between 1 and 2. The major constituents of test substance have molecular weights ranging from 506 to904 g/mol and an estimated log Kow exceeding 10. This suggests that the substance may not penetrate very easily through skin.

 

Based on QSAR prediction:

The above conclusion is supported by the predictions performed using the DERMWIN v2.01 application of EPISuite v4.1.

The calculated dermal permeability coefficient (Kp[1]) corresponded to:

-      Neodecanoic acid, oxiranylmethyl ester + 1 linseed oil:14.4 cm/h

-      BADGE + 2 linseed oil and derivatives: 6810 cm/h

 

However, it has been observed that the predicted Kp data from the usual QSAR programs are not suitable for lipophilic substances (CONCAWE, 2010). Therefore, the maximum flux (Jmax) or a dermal absorbed dose per event (DAD-event; mg/cm2), which provide better estimates for dermal penetration, have been used for predicting the dermal absorption potential for the substances in the current assessment. Jmax is the theoretically achieved dose, based on Fick’s first law of diffusion, when a material is maintained in a saturated solution or at steady state equilibrium whose flux describes the amount of permeant per unit time and area (i.e., μg/cm2/h).

 

In the absence of experimental data, it can be calculated by multiplying the water solubility with the predicted Kp values from DERMWIN model.

-      Neodecanoic acid oxiranylmethyl ester + 1 linseed oil: 5.42E-5μg/cm2/h

-      BADGE + 2 linseed oil and derivatives: 1.12E-11 μg/cm2/h

 

It has been suggested that ifJmax ≤0.1 μg/cm2/h, low skin penetration may be assigned with default skin absorption <10% (Shen et al. 2014[2]). Based on these calculations, the substance is predicted to be absorbed slowly, with no significant systemic uptake via the dermal exposure route.

 

Conclusion: Physico-chemical properties and QSAR predictions suggest that the test substance will not be absorbed significantly via skin. However, the test substance is a skin sensitizer which suggests some amount of dermal absorption. Therefore, a value of 10% has been considered for the risk assessment.

 

Inhalation absorption

Based on physico-chemical properties:

According to REACH guidance document R7.C (May 2014), inhalation absorption is maximal for substances with VP >25 KPa, particle size (<100 μm), low water solubility and moderate log Kow values (between -1 and 4). Very hydrophilic substances may be retained within the mucus and not available for absorption.

The test substance, because of its relatively low vapour pressure of 0.0018 at 25°C and 0.011 Pa at 60°C, will not be available as vapours for inhalation underambient or high temperature working conditions.As the substance is only used in the manufacturing of polyurethane dispersions in closed reactors, the pure substance will neither be available for inhalation as vapours nor as aerosols. Further, if at all there is any inhalation exposure, considering its physico-chemical properties (such as >10 log Kow, low water solubility and >500 MW of the most volatile component), no solubilisation in mucus is expected. Hence, the substance will most likely reach the lower respiratory tract after which the absorption fate of the deposited material will be similar to the oral route/gastrointestinal tract.

Conclusion: Overall, based on all the available weight of evidence, the test substance can be overall expected to have low to moderate absorption through the inhalation route. Nevertheless, a default value of 100% has been considered for the risk assessment.

 

Metabolism

The predicted metabolism of the test substance was evaluated using thein vivorat metabolism and rat liver S9 metabolism simulators of the OECD QSAR Toolbox v.3.4. According to thein vivorat metabolism simulator, the two major constituents are predicted to undergo epoxidation at the sites of unsaturation in the linseed oil fatty acid group. While as per the rat liver S9 metabolism simulator, both the constituents are predicted to primarily undergo oxidation at the site with OH group or ester hydrolysis. However, unlike BADGE + 2 linseed oil and because of the presence of two ester groups in the constituent, neodecanoic acid, oxiranylmethyl ester E10P + 1 linseed oil, the ester bond within the neodecanoic acid, oxiranylmethyl ester group is predicted to be more likely to be hydrolysed than the ester bond between the linseed oil fatty acid. (see table in CSR).

Bioaccumulation

Based on the physico-chemical information (i.e., >10 log Kow and low water solubility and high MW exceeding 500), it is concluded that the potential for bioaccumulation is low.

 

Excretion

Based on the high MW and low water solubility, the test substance as such is not expected to be excreted via urine. Nevertheless, there will be some urinary elimination following the formation of water soluble conjugates via Phase II metabolic reactions.

[1]Log Kp = -2.80 + 0.66 log kow – 0.0056 MW

[2]http://fragrancematerialsafetyresource.elsevier.com/sites/default/files/Shen-An_0.pdf