Sodium N-methyl-N-(1-oxo-9-octadecenyl)aminoacetate

Endpoint summary

Additional information

Justification for grouping of substances and read-across

The Sarcosine category contains N-acyl derivatives of N-methylglycine that function as hair-conditioning agents and surfactant-cleansing agents in cosmetic formulations. Other uses in non-cosmetic areas are known and some sarcosines are used in the metal finishing and processing industries as anti-rust agents. Their salts are known generally as N-acyl sarcosinates, fatty acid sarcosinates, or sarcosinates.

Structural similarities of the category substances are reflected in similar physico-chemical properties and mode of action. They have a common structural formula (see attachment), where R may be either hydrogen or sodium; the N-acyl part is a fatty acid chain ranging in length between 12 to 18 carbon atoms (R’ = C11 to C17) and having up to three unsaturations.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met. In particular for human toxicity, environmental fate and eco-toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across)”. Therefore, the available experimental data were collected and evaluated according to Annex XI in regard to:

-      Test duration (only tests which cover the expected exposure duration were regarded as suitable)

-      Key parameters of the test (only tests that cover the key parameter were accepted as suitable)

-      Comparability of the test systems

-      The adequacy of the results for C&L

-      The documentation of the test procedures (only in case of good documentation data)

Only data that were judged to cover the requirements specified above were used as adequate data suitable for the category and its members. In this particular case the similarity of the Sarcosine category members is justified, in accordance with the specifications listed in Regulation (EC) No 1907/2006 Annex XI, 1.5. Grouping of substances and read across, on basis of scope of variability and overlapping of composition, representative molecular structure, physico-chemical properties, toxicological, ecotoxicological profiles and supported by various QSAR methods. There is no convincing evidence that any one of these respective chemicals might lie out of the overall profile of this category. The key points that the members share are:

(i) Common origin: produced from condensation of fatty acids and N-methyl glycine. Typically the fatty acid needs to be activated in the form of chloride.

(ii) Similar structural features: long hydrophobic chain connected to a polar head through an amide bond

(iii) Similar physico-chemical properties: recognizable trends in melting point, boiling point, water solubility and partition coefficient. Similar surface tension activity.

(iv) Common properties for environmental fate & eco-toxicological profile: readily biodegradable, no potential for bioaccumulation, low to moderate adsorption potential, clear trend of increasing toxicity in aquatic organisms correlating with increasing carbon chain length, being the C18 compounds the most toxic substances.

(v) Similar metabolic pathways: the substances within the Sarcosine category have similar toxicokinetic behaviour that consists in no hydrolysis before absorption and absorption of the intact substance followed by a rapid excretion.

(vi) Common levels and mode of human health related effects: the available data on toxicological properties show that the substances of the Sarcosine category have similar toxicokinetic behaviour, no hydrolysis of the ester bond before absorption, absorption of the intact substance followed by a rapid excretion. The substances within the category showed acute toxicity via the inhalation route due to their irritant properties (reflected by their self-warning characteristics), skin irritating effects and severe damaging effects on the eye. Despite these corrosive/irritating effects, the constant pattern in toxicological properties within all substances considered herein consists in a lack of change of potency of properties. Thus, the category members showed no acute oral or dermal toxicity, no skin sensitisation properties, are of low systemic toxicity after repeated oral exposure, are not mutagenic or clastogenic, have shown no indication for reproduction toxicity and have no effect on intrauterine development.

Similar metabolic pathways

Toxicokinetic, metabolism and distribution

There are few experimental studies in which the toxicokinetic behaviour of the members of the Sarcosine category has been investigated.

In accordance with Annex VIII, Column 1, Item 8.8.1. of Regulation (EC) 1907/2006 and with Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance (ECHA, 2012), assessment of the toxicokinetic behaviour of the substances of the Sarcosine category is conducted to the extent that can be derived from the relevant available information. This comprises a qualitative assessment of the available substance specific data on physico-chemical and toxicological properties according to Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance (ECHA, 2012) and taking into account further available information on the Sarcosine category.

Substances within the Sarcosine category meet the definition of a mono-constituent substance based on the analytical characterization except for Reaction products of oleoyl sarcosine with sodium hydroxide which meets the definition for a UVCB. Substances within the Sarcosine category are solid (except for (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8), which is a viscous liquid) and have molecular weights which range between 271-375 g/mol.

Acid members of the category show high log Pow values (> 4) while the salt member values range between low and moderate (all < 4).

The vapour pressure is calculated to be between 39.9 Pa and < 0.001 Pa).

Absorption

Absorption is a function of the potential for a substance to diffuse across biological membranes. The most useful parameters providing information on this potential are the molecular weight, the octanol/water partition coefficient (log Pow) value and the water solubility. The log Pow value provides information on the relative solubility of the substance in water and lipids (ECHA, 2012).

Oral

The smaller the molecule, the more easily it will be taken up. In general, molecular weights below 500 g/mol are favourable for oral absorption (ECHA, 2012). As the molecular weight of substances within the Sarcosine category ranges between 271-375 g/mol, absorption of the molecules in the gastrointestinal tract is in general anticipated. Absorption after oral administration is also expected when the “Lipinski Rule of Five” (Lipinski et al. (2001), Ghose et al. (1999)) is applied to the substances within the Sarcosine category, as all rules are fulfilled for the substances N-lauroylsarcsoine (CAS 97-78-9), Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3), and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8). For the substance N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3) all rules are fulfilled except for the log Pow, which is above the given range of -0.4 to 5.6.

With regard to the oral bioavailability it has been shown that after oral ingestion, Sodium N-lauroyl sarcosinate (CAS 137-16-6) was not hydrolysed by either gastric or intestinal enzymes in vitro (CIR, 2001).

There is a study on oral absorption of Sodium lauroyl sarcosinate (CAS 137-16-6) which was applied at a dose of 2.6 µg per animal to teeth, oral mucosa and tongue of 15 rats. Five rats each were examined at the time of application, and 4 and 24 h after application. Immediately after administration, the mean distribution of the [14]C was 1.2% in the teeth and 2.22% in the tongue. At 4 h, the mean distribution was 0.92% in the teeth, 0.95% in the oral mucosa, 0.57% in the tongue, 5.44% in the liver, 2.78% in the kidneys, 0.87% in the faeces and 33.5% in the urine. At 24 h the mean distribution was 0.079% in the teeth, 0.92% in the oral mucosa, 0.57% in the tongue, 1.6% in the liver, 0.8% in the kidney, 1.8% in the faeces and 42.2% in the urine. About 1% of the compound adhered to both the teeth and the oral mucosa, and 0.57% adhered to the tongue; this adherence was such that no radioactivity could be washed from those tissues by a physiological saline solution. The data indicated that Sodium N-lauroyl sarcosinate (CAS 137-16-6) was not absorbed by the tissues of the mouth, but was swallowed and absorbed into the blood (Allison 1994, CIR 2001).

The available data on acute and repeated dose toxicity via the oral route of the substances within the Sarcosine category are also considered for assessment of oral absorption. Acute oral studies conducted with category members Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) showed LD50 values > 5000 mg/kg bw and no systemic effects at the end of the observation period (Haynes, 1987 and Sarasin, 1980).

Data on repeated dose toxicity is available from a subchronic and a 2-year oral study with Sodium N-lauroylsarcosinate (CAS 137-16-6). No adverse systemic effects were observed in both studies, and NOAELs of ≥ 250 mg/kg bw/day (highest dose tested) and 1000 mg/kg bw/day were derived from the subchronic study and the chronic study, respectively.

The available studies show that different category members of the Sarcosine category reveal only a low potential for toxicity after acute and repeated exposure, but no assumptions can be made regarding the absorption potential based on the experimental data.

Overall, a systemic bioavailability after oral uptake of the substances within the Sarcosine category is considered likely.

Dermal

It is commonly accepted that smaller molecules are taken up through the skin more easily than bigger ones; the smaller the molecule, the more easily it may be taken up. In general a molecular weight below 100 g/mol favours dermal absorption, above 500 g/mol the molecule may be too large (ECHA, 2012).

As the molecular weight of substances within the Sarcosine category ranges between 271-375 g/mol, a dermal absorption of the molecules cannot be excluded.

If a substance is a skin irritant or corrosive, damage to the skin surface may enhance penetration. Furthermore, if a substance has been identified as skin sensitiser, then some uptake must have occurred previously, although it may only have been a small fraction of the applied dose (ECHA, 2012).

As the members of the Sarcosine category are considered as skin irritants in humans, an enhanced penetration of the substances due to local skin damage cannot be excluded. However, within the Sarcosine category, no skin sensitisation potential has been identified.

Based on QSAR-calculations the dermal absorption values of the substances of the Sarcosine category vary between 0.0010 and 0.00004 mg/cm²/event (low or very low dermal absorption).

According to these values, substances within the Sarcosine category have only a low potential for dermal absorption.

In general, the dermal uptake of substances with a high water solubility of > 10 g/L (and log Pow < 0) will be low, as those substances may be too hydrophilic to cross the stratum corneum.

Log Pow values between 1 and 4 favour dermal absorption (values between 2 and 3 are optimal), in particular if water solubility is high. In contrast, log Pow values < –1 suggest that a substance is not likely to be sufficiently lipophilic to cross the stratum corneum, therefore dermal absorption is likely to be low (ECHA, 2012). As Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3), and Reaction products of oleoyl sarcosine with sodium hydroxide have log Pow values between 0.37 and 3.92 and water solubilities between 300-400 g/L, dermal uptake is likely.

For substances with a log Pow above 4, the rate of dermal penetration is limited by the rate of transfer between the stratum corneum and the epidermis, but uptake into the stratum corneum will be high. For substances with a log Pow above 6, the rate of transfer between the stratum corneum and the epidermis will be slow and will limit absorption across the skin, and the uptake into the stratum corneum itself will also be slow. As the log Pow of the substances N-lauroylsarcosine (CAS 97-78-9), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) is > 4, dermal uptake is likely to be low.

The available data on dermal toxicity of the category member Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) are also considered for assessment of dermal absorption. An acute dermal study was available for Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3). At a concentration of up to 2000 mg/kg bw in rats no signs of systemic toxicity were seen (Bradshaw, 2013). An alternative possible explanation for the lack of systemic toxicity via the dermal route, apart from a low toxic potential, could be limited dermal absorption. However, based on the available data the reason for the lack of acute toxicity via the dermal route cannot be unequivocally decided.

Considering all available data on the members of the Sarcosine category a low dermal absorption is assumed for these substances.

Inhalation

Members of the Sarcosine category have a low vapour pressure of (between < 0.001 Pa and 39.9 Pa at 25 °C) thus being of low volatility. Therefore, under normal use and handling conditions, inhalation exposure and thus availability for respiratory absorption of the substances in the form of vapours, or gases, is not expected to be significant.

However, the substances may be available for respiratory absorption in the lung after inhalation of aerosols, if the substances are sprayed. In humans, particles with aerodynamic diameters below 100 μm have the potential to be inhaled. Particles with aerodynamic diameters below 50 μm may reach the thoracic region and those below 15 μm the alveolar region of the respiratory tract (ECHA, 2012).

Moderate log Pow values (between -1 and 4) are favourable for absorption directly across the respiratory tract epithelium by passive diffusion, while lipophilic compounds with a log Kow > 4, that are poorly soluble in water (1 mg/L or less), can be taken up by micellar solubilisation.

Inhalation studies conducted with Sodium N-laurolysarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) resulted in 0.5 mg/L < LC50 < 5 mg/L air. The most common clinical signs in all studies were shallow respiration, slow breathing and laboured respiration, slight staggering, bloody nose area, low motility, and areas with hair loss.

Overall, taken the physico-chemical parameters and the acute inhalation toxicity data into consideration, respiratory absorption for the substances in the Sarcosine category is assumed to be likely. However, absorption by the inhalative route under realistic conditions is not assumed to be higher than that via the oral route, as the effects observed in the inhalation studies are due to the local irritative effects (destruction of the fluid film of the broncheo-alveolar tract due to surface activity) of the substances, and the resulting self-warning effect due to respiratory irritation will prevent unintentional exposure. Therefore inhalation (and absorption) of adverse doses is unlikely under realistic conditions, and the anticipation of equal absorption for the oral and the inhalative route for risk assessment is considered to be sufficiently conservative.

Distribution/Accumulation

The distribution of the test substance was investigated in an oral absorption study where [14C] Sodium N-lauroylsarcosinate was applied to teeth, oral mucosa and tongue of 15 rats at a dose of 2.6 µg per animal. The distribution of the radioactivity in tissues at the time of treatment was 0.09 mg/g in the teeth, 0.1 mg/g in the oral mucosa, and 0.1 mg/g in the tongue. Four hours after treatment the distribution was 0.07 mg/g in the teeth, 0.05 mg/g in the oral mucosa, 0.02 mg/g in the tongue, 0.003 mg/g in the blood, 0.015 mg/g in the liver, 0.026 mg/g in the kidneys, 0.006 mg/g in the bones and 0.009 mg/g in the muscles. At 24 hours the distribution was 0.09 mg/g in the teeth, 0.05 mg/g in the oral mucosa, 0.02 mg/g in the tongue, 0.003 mg/g in the blood, 0.005 mg/g in the liver, 0.008 mg/g in the kidneys, 0.01 mg/g in the bones and 0.006 mg/g in the muscles (Allison 1994, CIR 2001).

In other studies the teeth of rats were brushed with dentifrice containing 2 x 10³ µg [14C] Sodium N-lauroylsarcosinate. The test substance was taken up from the dentifrice by the teeth, oral mucosa and tongue in a way that a certain amount could not be rinsed away with saline solution. However, frequent application did not cause accumulation of radioactivity in bone or muscle above the one mentioned earlier in this assessment (Allison 1994, CIR 2001).

Metabolism/Excretion

In the oral absorption study described above, where [14C] Sodium N-lauroylsarcosinate was applied to teeth, oral mucosa, and tongue of 15 rats at a dose of 2.6 µg per animal, approximately 34% of the activity of the test material was excreted in the urine over a period of 4 h after application, demonstrating rapid absorption and excretion. Some 42% of the activity was excreted during 24 h. The remainder of the activity could approximately be accounted for by estimating the total amount of activity in the blood, muscles, bone and other tissues of the body, indicating that very little, if any, of the compound was oxidized to form CO₂ (Allison 1994, CIR 2001).

In addition, further experimental data show that after oral administration of [14C] Sodium N-lauroylsarcosinate to rats 82 to 89% of a 50 mg/kg bw dose was excreted in the urine and faeces within 24 h. For the next 24 h, 1 to 2 % was excreted. Nearly all of the excreted material was found in the urine (CIR, 2001).

Finally, the fact that the major function of a group of substances structurally similar to Sarcosines and Sarcosinates, the N-Acylamino acids, would appear to be in the detoxification and excretion of xenobiotic carboxylates (Farrel, 2008) strengthens the hypothesis that the main excretion route for Sarcosines and Sarcosinates is by urinary excretion.

Similar mammalian toxicity profiles

The available data on toxicological properties show that the substances within the Sarcosine category have similar toxicokinetic behaviour, the ester bond is not hydrolysed before absorption, and absorption of the intact substance is followed by a rapid excretion. Substances within the Sarcosine category showed acute toxicity via the inhalation route due to their irritant properties (self-warning characteristics due to respiratory irritation), skin irritating effects at concentrations > 30%, and severe damaging effects on the eye. Despite these corrosive/irritating effects, the constant pattern in toxicological properties of all substances considered herein consists in a lack of change of potency. Thus, the category members showed no acute oral or dermal toxicity, no skin sensitisation properties, are of low systemic toxicity after repeated oral exposure, are not mutagenic or clastogenic, have shown no indication for reproduction toxicity and have no effect on intrauterine development.

Acute toxicity oral / inhalation / dermal

The available data indicate a low level of acute oral and dermal toxicity for the Sarcosine category members and thus no hazard for acute oral, dermal toxicity was identified.

The available data on inhalation indicate toxicity for the Sarcosine category members and thus a medium hazard was identified for acute inhalation

Acute oral toxicity

Acute oral toxicity studies of acceptable quality and reliability are available for Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine(CAS 110-25-8), showing no mortality at doses greater than 5000 mg/kg bw. No clinical signs of toxicity were observed for the category members Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8). Based on the identified common metabolic pathway, the available studies indicate a low level of acute oral toxicity for all members of the Sarcosine category.

Acute inhalation toxicity

Four acute inhalation toxicity studies are available for the category members Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8). For the substance Sodium N-lauroylsarcosinate (CAS 137-16-6) a first study with the neat, pulverised test substance was conducted. The LC50 for both males and females was 0.05-0.5 mg/L. During exposure to 1 mg/L of the test substance most animals showed laboured respiration. No clinical signs were noted during exposure at 5, 0.5 and 0.05 mg/L. The neat test material meets therefore the criteria to be classified for acute inhalation toxicity Cat. 2, H330 according to Regulation (EC) No 1272/2008 and Toxicity by inhalation (T, R23) according to Directive 67/548/EC.

The second available study for Sodium N-lauroylsarcosinate (CAS 137-16-6) was performed with an aqueous formulation at a concentration of approx. 35%. LC50 for both males and females for the 34.5% aqueous solution of the test substance was 1 - 5 mg/L. Clinical signs noted during exposure with 0.5 mg/L were shallow respiration in all animals. After exposure, the only clinical sign noted was the chromodacryorrhoea in one male on Day 2. At 1 mg/L, shallow respiration was noted in all animals during exposure. After exposure, hunched posture, slow breathing and/or piloerection was noted among all animals between Days 1 and 3. Slow breathing and laboured respiration were seen in all animals during treatment with 5 mg/L. After exposure, lethargy, hunched posture, slow breathing, laboured respiration and/or piloerection were observed in the animals that were sacrificed for humane reasons on the day of exposure.

The 34.5% aqueous solution of the test substance meets therefore the criteria to be classified for acute inhalation toxicity Cat. 4, H332 according to Regulation (EC) No 1272/2008 and as Harmful by inhalation (Xn, R20) according to Directive 67/548/EC. The second study performed with a 34.5% aqueous formulation of Sodium N-lauroylsarcosinate (CAS 137-16-6), which is the highest technically attainable concentration during the manufacturing process, more closely reflects the potential for acute inhalation toxicity under realistic conditions and at concentrations relevant for human exposure. The data obtained from this study is used to determine specific concentration limits and to derive a classification for the marketed product. This is in compliance with the conditions under which N-lauroylsarcosine (CAS 97-78-9), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) and N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3) are manufactured and marketed. Therefore, using the result of the acute inhalation toxicity study testing a 34.5% aqueous formulation of Sodium N-lauroylsarcosinate (CAS 137-16-6) for the hazard assessment of N-lauroylsarcosine (CAS 97-78-9), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) and N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3) is appropriate.

Two acute inhalation studies were conducted with the category member (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8). In the first study the LC50 was calculated to be 1.8 mg/L air for females and 1.05 mg/L air for males. The combined LC50 value for males and females is considered to be 1.37 mg/L air after 4 h exposure to the test material. Clinical signs of toxicity were observed in all surviving animals including flight attempts, gasping and noisy breathing, slight staggering, bloody nose area, low motility, hair loss in the head area and salivation in varying degrees.

In the second study the LC50 for male and female animals is calculated to be > 1.01 – 1.85 mg/L air after 1 h exposure. Except in the lowest dose group, the animals of all other groups had eye and nose exudate, eyelid closure, dyspnoea, staggering, cowering position and scrubby substance-clotted fur.

Thus, the test substance meets the criteria to be classified for acute inhalation toxicity Cat. 4, H332 according to Regulation (EC) No 1272/2008 and as Harmful by inhalation (Xn, R20) according to Directive 67/548/EC.

Following the category approach and applying the concept of interpolation the classification is adopted for all substances of the category.

Acute dermal toxicity

The available acute dermal toxicity data for the category member Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) consistently showed no treatment-related mortalities. Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) induced no clinical signs of toxicity up to the end of the 14-day observation period. However, based on the lack of treatment-related mortalities and absence of clinical signs of toxicity, an overall LD50 dermal > 2000 mg/kg bw was derived for the category members. Taken into account the generally low dermal absorption rate, a low level of acute dermal toxicity for all Sarcosine category members is expected.

Skin and Eye irritation / corrosion

Skin

There are in vivo and/or in vitro studies available for the category members Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) Reaction products of oleoyl sarcosine with sodium hydroxide and (Z)-N-methyl-N-(1-oxo-9-octydecenyl) glycine (CAS 110-25-8); no studies are available for N-lauroylsarcosine (CAS 97-78-9) and N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3), but due to the similarity to their corresponding sodium salts the available information on the salts is used for read across based on the category approach.

Since the available data on skin irritation indicated that effects on skin were depending on the concentration tested, a concentration of 30% was established as specific concentration limit for those category members with acyl chain lengths of 12 and 14 C-atoms. At the specific concentration limit of 30% and below, the category members N-lauroylsarcosine (CAS 97-78-9), Sodium N-lauroylsarcosinate (CAS 137-16-6), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3), and Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) are not classified as skin irritating.

However, in an in vivo study with the category member Reaction products of oleoyl sarcosine with sodium hydroxide well defined to moderate to severe erythema was observed in all animals at 1, 24, 48 and 72 h after application while slight to moderate oedema was observed in all animals at 24, 48 and 72 h after application .

The two in vivo studies available for the category member (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) indicate that the neat substance causes skin irritation, as well.

Thus, based on the data available for neat Reaction products of oleoyl sarcosine with sodium hydroxide and neat (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) both were classified as irritating to the skin, and no specific concentration limits were applied for these two substances.

Eye

There are in vivo and/or in vitro studies available for the category members Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3), Reaction products of oleoyl sarcosine with sodium hydroxide and (Z)-N-methyl-N-(1-oxo-9-octydecenyl) glycine (CAS 110-25-8); no studies are available for N-lauroylsarcosine (CAS 97-78-9) and N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3), but due to the similarity to their corresponding sodium salts the available information on their respective salts is used for read across based on the category approach.

Two in vivo eye irritation studies on the category member Sodium N-lauroylsarcosinate (CAS 137-16-6), conducted at concentrations of 10 and 30%, show that the substance has eye irritating properties at both concentrations; therefore, the induction of severe eye damage has to be anticipated for treatment with concentrations > 30% a.i., which is established as specific concentration limit, in a worst case assumption. For concentrations ≥ 1% and ≤ 30% a.i. the substance is expected to induce eye irritation based on the available information and according to the criteria of Regulation (EC) No 1272/2008. Due to the lack of substance specific data the same classification is adopted for N-lauroylsarcosine (CAS 97-78-9) according to read across based on the category approach.

In addition, an in vitro and an in vivo study conducted with the neat category member Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) and at a concentration of 30% a.i., respectively, show potential to cause severe damage to the eyes. This is similar to the already registered category member (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) which is also classified as causing severe damage to the eyes.

An in vitro test eye irritation test only is available for Reaction products of oleoyl sarcosine and sodium hydroxide, demonstrating only minimal irritation potential to the eye; however, as the available information was not sufficient for hazard assessment read across based on the category approach from the structurally closely related category member (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) (corresponding acid) was conducted and the classification of the source substance adopted.

Since the available data on eye irritation of Sodium-N-lauroylsarcosinate (CAS 137-16-6) indicate that effects on the eye were dependent on the concentration of the active substance in solution, specific concentration limits for the induction of eye irritation and serious damage to the eyes were established for Sodium N-lauroylsarcosinate (CAS 137-16-6) and N-lauroylsarcosine (CAS 97-78-9); the other category members were classified as inducing severe damage to the eyes, and the generic concentration limits apply to them.

Skin sensitisation

The available data on skin sensitisation of the category members Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) show that no skin sensitisation was induced in any of the studies performed. Based on the comprehensive data on category members covering a broad range of sarcosines/sarcosinates with acyl chain lengths from C12 to C18, there is strong evidence that none of the other members of the Sarcosine category will show a skin sensitising potential, either, and the data requirements of the endpoint are covered by read across based on interpolation between Sodium N-lauroylsarcosinate (CAS 137-16-6) (C12 sarcosinate) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) (C18 sarcosine).

In addition, the protein binding properties of Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) were assessed to predict skin sensitization potential using the OECD QSAR Toolbox, v2.3. The substance was predicted to be negative for protein binding potential.

Repeated dose toxicity oral

A subchronic oral and a 2-year oral study are available for the category member Sodium N-lauroylsarcosinate (CAS 137-16-6). Both studies showed no adverse systemic effects resulting in NOAELs of ≥ 250 mg/kg bw/day derived from the subchronic study and ≥ 1000 mg/kg bw/day derived from the chronic study. Since the NOAEL of 1000 mg/kg bw/day was derived from the study with the longest study duration and no adverse effect was observed in the subchronic study up to and including the highest dose of 250 mg/kg bw/day tested, the higher value is considered to be the most reliable dose descriptor. Thus, as a weight of evidence approach, a NOAEL of 1000 mg/kg bw/day after chronic oral application is concluded. Based on the common metabolic fate of all members within the Sarcosine category after oral administration, no systemic toxicity is expected to occur after repeated oral exposure to any other category member, either. Thus, the overall NOAEL within the category is considered to be ≥ 1000 mg/kg bw/day.

There are no data available on the repeated dose toxicity after dermal application and inhalation of the category members, since dermal absorption is considered negligibly low and the inhalation exposure is excluded based on the low vapour pressure and the form of marketing.

Genetic toxicity in vitroand in vivo

Six studies investigating the potential genetic toxicity in vitro in bacteria (Ames test) were performed with the category members Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-52-1), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3), Reaction products of oleoyl sarcosine with sodium hydroxide and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8), consistently showing negative results in the presence and absence of metabolic activation up to the maximum concentration of 5000 µg/plate.

Three in vitro chromosomal aberration tests are available for the category members Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-52-1) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) which do not show clastogenic activity in vitro. Similarly, three in vitro mammalian cell gene mutation assays are available for Sodium N-lauroylsarcosinate (CAS 137-16-6), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-52-1) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) which gave negative results for mutagenicity in mammalian cells, either.

Since all available data on the in vitro genetic toxicity of the category members were negative the conduction of in vivo studies is not indicated, and it is concluded that none of the category members will show any genotoxic potential.

Toxicity to reproduction

A reliable reproduction/developmental screening test was performed with the category member (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) via oral gavage, showing no toxicologically relevant effects on reproduction up to and including the highest dose level of 1000 mg/kg bw/day.

Based on the common metabolic fate of all members within the Sarcosine category after oral administration, no reproduction toxicity is expected to occur after treatment with any of the category members. Thus, the overall NOAEL within the category is considered to be ≥ 1000 mg/kg bw/day.

However, it must be noted that a reproductive/developmental toxicity screening study is not suitable to exclude for sure the presence of toxic effects to reproduction if the result is negative. Nevertheless, together with the results of the subchronic and chronic toxicity investigations (no effects on male or female reproductive organs), it can be concluded that Sarcosines and Sarcosinates are substances of no concern with regard to toxicity to reproduction.

Developmental toxicity

No reliable prenatal developmental toxicity study is available within the Sarcosine category. Therefore, a prenatal developmental toxicity study according to OECD guideline 414 has been proposed for Sodium N-lauroylsarcosinate (CAS 137-16-6) as a representative member of the category in 2010. Once available the data will be used to fulfil the endpoint-specific data requirements for the other category members by read across based on the category approach and considering animal welfare aspects. The further testing strategy is dependent on the outcome of that study.

Classification

According to the classification criteria of Regulation (EC) No. 1272/2008 (CLP) and Directive 67/548/EEC (DSD) and based on the available data, the members of the Sarcosine category N-lauroylsarcosine (CAS 97-78-9, SCL: >30%), Sodium N-lauroylsarcosinate (CAS 137-16-6, SCL: > 30%), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3, SCL: > 30%), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3, SCL: > 30%), Reaction products of oleoyl sarcosine with sodium hydroxide and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) meet the criteria for classification for Skin Irritation Category 2 (H315) and as Skin irritating (Xi; R38), respectively.

Furthermore, N-lauroylsarcosine (CAS 97-78-9, SCL: > 30%), Sodium N-lauroylsarcosinate (CAS 137-16-6, SCL> 30%), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3), Reaction products of oleoyl sarcosine with sodium hydroxide and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) meet the criteria for classification for Eye Damage Category 1 (H318) according to Regulation (EC) No 1272/2008 and as Risk of serious damage to eye (Xi; R41) according to Directive 67/548/EEC.

N-lauroylsarcosine (CAS 97-78-9) and Sodium N-lauroylsarcosinate (CAS 137-16-6) at concentrations ≥ 1% and ≤ 30% meet the classification criteria for Eye Irritation Category 2 (H319) according to Regulation (EC) No 1272/2008 and as Irritating to the eye (Xi; R36) at concentrations ≥ 5% and ≤ 30% according to Directive 67/548/EEC.

Category members N-lauroylsarcosine (CAS 97-78-9; SCL: ≤ 34.5%), Sodium N-lauroylsarcosinate (CAS 137-16-6; SCL: ≤ 34.5%), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3; SCL: ≤ 34.5%), Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3; SCL: ≤ 34.5%), Reaction products of oleoyl sarcosine with sodium hydroxide and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) meet the criteria for classification as Acute toxicity - inhalation Category 4 (H332) according to Regulation (EC) No 1272/2008 and as Harmful by inhalation (Xn; R20) according to Directive 67/548/EEC.

The category members N-lauroylsarcosine (CAS 97-78-9), Sodium N-lauroylsarcosinate (CAS 137-16-6), N-(1-oxotetradecyl) sarcosine (CAS 52558-73-3) and Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3) meet the criteria for classification as Acute toxicity - inhalation Category 2 (H330) according to Regulation (EC) No 1272/2008 and as Toxic by inhalation (T, R23) according to Directive 67/548/EC at concentrations > 34.5%.

Data matrices

Mammalian toxicity (1)(*)

ID No.	Substance	CAS No.	Basic Toxicokinetics and Dermal absorption	Acute toxicity oral	Acute toxicity inhalation	Acute toxicity dermal
# 1	N-lauroylsarcosine	97-78-9	ER + RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) Absorption:bioavailable via oral and inhalation route Metabolism:no pancreatic or gastric hydrolysis Excretion: urinary excretion mainly	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)	RA from Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-62-1)
# 2	Sodium N-lauroylsarcosinate	137-16-6	ER: Excretion: urinary excretion mainly	ER: LD50> 5000 mg/kg bw	ER: LC50: 0.05 - 0.5 mg/L air (neat test substance); acute toxicity Cat 2 LC50> 1 -≤5 mg/L air (34.5% aqueous solution); acute toxicity Cat 4	waiving
# 3	N-(1-oxotetradecyl) sarcosine	52558-73-3	ER + RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) Absorption:bioavailable via oral and inhalation route Metabolism:no gastric or intestinal hydrolysis Excretion: urinary excretion mainly	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)	RA from Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-62-1)
# 4	Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate	30364-51-3	ER + RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) Absorption:bioavailable via oral and inhalation route Metabolism:no pancreatic or gastric hydrolysis Excretion: urinary excretion mainly	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)	ER: LD50> 2000 mg/kg bw
# 5	(Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine	110-25-8	ER + RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) Absorption: bioavailable via oral and inhalation route Metabolism: no gastric or intestinal hydrolysis Excretion: urinary excretion mainly	ER: LD50> 5000 mg/kg bw	ER: LC50= 1.37 mg/L air	waiving
# 6	Reaction products of oleoyl sarcosine with sodium hydroxide	--	ER + RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) Absorption: bioavailable via oral and inhalation route Metabolism: no gastric or intestinal hydrolysis Excretion: urinary excretion mainly	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	RA from (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	RA from Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-62-1)

(*) substances marked in bold are registered under REACH Regulation EC 1907/2006 in 2013; the remaining substances were registered in 2010 or will be registered later.

Mammalian toxicity (2)(*)

ID No.	Substance	CAS No.	Skin Irritation	Eye irritation	Skin Sensitisation	Repeated dose toxicity
# 1	N-lauroylsarcosine	97-78-9	ER SCL: > 30 % irritating	ER: corrosive	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)
# 2	Sodium N-lauroylsarcosinate	137-16-6	ER SCL: > 30 % irritating	ER: ≥ 30% irritating	ER: not sensitising	ER: WoE NOAEL (male/female, subchronic, oral) ≥ 250 mg/kg bw/day; NOAEL (male/female, chronic, oral) ≥ 1000 mg/kg bw/day
# 3	N-(1-oxotetradecyl) sarcosine	52558-73-3	ER SCL: > 30 % irritating	ER: corrosive	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)
# 4	Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate	30364-51-3	ER SCL: > 30 % irritating	ER: corrosive	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)
# 5	(Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine	110-25-8	ER: irritating	ER: corrosive	ER: not sensitising	ER: NOAEC (male/female, subacute, inhalation) > 0.06 mg/L RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)
# 6	Reaction products of oleoyl sarcosine with sodium hydroxide	--	ER SCL: > 30 % irritating	ER: corrosive	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6)

(*) substances marked in bold are registered under REACH Regulation EC 1907/2006 in 2013; the remaining substances were registered in 2010 or will be registered later.

Mammalian toxicity (3) (*)

ID No.	Substance	CAS No.	Genetic Toxicity in vitro			Genetic Toxicity in vivo	Toxicity to reproduction	Developmental Toxicity / teratogenicity
			Gene mutation in bacteria	Cytogenicity in mammalian cells	Gene mutation in mammalian cells
# 1	N-lauroylsarcosine	97-78-9	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	--	RA from (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	waiving
# 2	Sodium N-lauroylsarcosinate	137-16-6	ER: not mutagenic	ER: not clastogenic	ER: not mutagenic	--	RA from (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	Test proposal
# 3	N-(1-oxotetradecyl) sarcosine	52558-73-3	ER: not mutagenic	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6), (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) and Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3)	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6), (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8) and Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate (CAS 30364-51-3)	--	RA from (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	waiving
# 4	Sodium N-methyl-N-(1-oxotetradecyl) aminoacetate	30364-51-3	ER: not mutagenic	ER: not clastogenic	ER: not mutagenic	--	RA from (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	waiving
# 5	(Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine	110-25-8	ER: not mutagenic	ER: not clastogenic	ER: not mutagenic	--	ER: NOAEL ≥ 1000 mg/kg bw/day	waiving
# 6	Reaction products of oleoyl sarcosine with sodium hydroxide	--	ER: not mutagenic	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	RA from Sodium N-lauroylsarcosinate (CAS 137-16-6) and (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8	--	RA from (Z)-N-methyl-N-(1-oxo-9-octadecenyl) glycine (CAS 110-25-8)	waiving

(*) substances marked in bold are registered under REACH Regulation EC 1907/2006 in 2013, the remaining substances were registered in 2010 or will be registered later.

Abbreviations:

ER - experimental result

RA – read across

WoE – weight of evidence

References

Allison JB et al. (1994). The distribution of C14 from compound 105 in the rat. Hampshire Chemical Corporation. 3: 58-66.

ECHA (2012). Guidance on information requirements and chemical safety assessment, Chapter R.7c: Endpoint specific guidance.

Farrell EK and Markler DJ (2008). Biosynthesis, degradation and pharmacological importance of the fatty acid amides. Drug Discovery Today 13 (13-14): 558-568

CIR (2001). Final Report on the Safety Assessment of Cocoyl Sarcosine, Lauroyl Sarcosine, Myristoyl Sarcosine, Oleoyl Sarcosine, Stearoyl Sarcosine, Sodium Cocoyl Sarcosinate, Sodium Lauroyl Sarcosinate, Sodium Myristoyl Sarcosinate, Ammonium Cocoyl Sarcosinate, and Ammonium Lauroyl Sarcosinate” (see IJT, 10 (Suppl1): 1-14, 2001)

Ghose et al. (1999). A Knowledge-Based Approach in Designing Combinatorial or Medicinal Chemistry Libraries for Drug Discovery. J. Comb. Chem. 1 (1): 55-68.

Lipinski et al. (2001). Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings. Adv. Drug Del. Rev. 46: 3-26.