Dodecanoic acid, 2,2-dimethyl-3-oxopropyl ester

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics

Type of information:

other: expert statement

Adequacy of study:

key study

Study period:

15.08.2005

Reliability:

1 (reliable without restriction)

Objective of study:

toxicokinetics

Qualifier:

no guideline required

GLP compliance:

not specified

Radiolabelling:

no

Details on test animals or test system and environmental conditions:

Not applicable.

Details on exposure:

Not applicable.

Duration and frequency of treatment / exposure:

Not applicable.

Remarks:

Doses / Concentrations:
Not applicable.

No. of animals per sex per dose / concentration:

Not applicable.

Positive control reference chemical:

Not applicable.

Details on study design:

Not applicable.

Details on dosing and sampling:

Not applicable.

Statistics:

Not applicable.

Preliminary studies:

The estimated partition coefficient reveals that the compound may have the ability to penetrate skin. However, even if absorbed by skin, its toxicity is very low, as shown in the acute dermal toxicity study. Due to its low water solubility, the compound will most likely not solubilise in the stomach and thus probably not be absorbed in the GI-tract as such. Based on the data obtained in the water solubility study, the test item will most likely degrade rapidly upon entry of the body, forming several polar degradation products. These can be excreted quickly. This assumption is supported by the low acute oral toxicity and low toxicity observed in the 28-day toxicity study. However, small amounts of the test item have been probably absorbed after oral administration based on the results of the 90-day repeated dose study. In this study alterations in the spleen in the form of macroscopically enlargement associated with increases in spleen weight and accompanied by splenic hyperplasia in male and female rats were observed.

Application of 2,2-dimethyl-3-lauroyloxy-propanal to skin and eyes of rabbits did not cause any irritation or corrosion, nor where there any sensitising effects observed. In addition, topical application of high concentrations of compound did not cause any local effects or systemic toxicity.

Absorbed by the body, following ingestion or passage through the skin, the aldehyde 2,2-dimethyl-3-lauroyloxy-propanal will degrade rapidly and distribute by systemic circulation, as will the degradation (oxidation and hydrolysis) products. One of the most important pathway of aldehyde metabolism is oxidation to carboxylic acids by aldehyde dehydrogenases (Vasiliou et al., 2000). The enzymes involved in these detoxification reactions most probably belong to the category of aldehyde dehydrogenases known to be relatively substrate unspecific, but effective in protecting organisms from potentially harmful xenobiotics (Sladek, 2003). Other phase I metabolic reactions may include cytochrome P450 mediated transformations such as aldehyde reductions or aldehyde scissions. Following phase I metabolic reactions and/or chemical degradation, the formed metabolites are rendered more polar by phase II metabolism. Most likely the carboxylic acid metabolites are ultimately conjugated with glycine or glutamine, before being excreted in urine or bile.

It is unlikely that metabolism will render the aldehyde compound more toxic, forming reactive products. This assumption is supported by results obtained in an in vitro Ames test and chromosome aberration test. In both assays no significant increases in toxicity were noted, in the presence of a rodent microsomal S9-fraction. This indicates that formation of reactive metabolites is rather unlikely.

Based on the compound’s structure and associated physical-chemical characteristics, particularly its limited stability in water-based systems, the compound is hardly bioavailable as such and thus, bioaccumulation is not likely to occur. Absorbed or bioavailable compound most likely degrades and decomposition products are further metabolised and excreted or excreted as such. Formation of toxic metabolites is unlikely, based on the results of oral and dermal toxicity studies and two studies using isolated S9-fractions.

Conclusions:

no bioaccumulation potential based on study results

Executive summary:

General  

The aldehyde 2,2-dimethyl-3-lauroyloxy-propanal is formed during the hydrolysis of Sika Härter LJ, Sika Härter LH and Sika Härter LTJ. All three Sika Härter are hardeners for polyurethane moisture hardening adhesives and sealant. During the hardening process the hardeners are rapidly hydrolysed, forming the aldehyde 2,2-dimethyl-3-lauroyloxy-propanal and corresponding polyamines.  

Typically, the hardeners react with the polyurethane mass and become chemically bound components within the polymer matrix, irreversibly integrating the aldehyde. If not integrated in a polyurethane matrix, 2,2-dimethyl-3-lauroyloxy-propanal is prone to oxidation by air or hydrolysis in water. Principal oxidation product is 2,2-dimethyl-3-lauroyloxy-propanoic acid (a carbonic acid). Conversion of aldehyde to carbonic acid by air oxygen is slow and generally the process takes hours to days. Hydrolysis in water on the other hand, is a more rapid process and, as shown in the solubility study, so fast it even prevents the compound from reaching a solubility equilibrium. Thus, the compound is extremely unstable in water and no true water solubility could be determined. Besides the carbonic acid several other polar hydrolysis products (short-chain) were noted within minutes following contact with water.  

 

Toxicological Profile of 2,2-Dimethyl-3-lauroyloxy-propanal 

Based on the LD50-values ( > 2,000 mg/kg bw) from acute oral and acute dermal toxicity studies in rats, 2,2-dimethyl-3-lauroyloxy-propanal is of low acute toxicity. In a 28-day toxicity study a NOEL of 1000 mg/kg bw/day was observed. A NOAEL was determined to be 300 mg/kg bw/d in male and female rats in a 90-day repeated dose study.The reprotoxic properties of the test item were assessed in a study performed according to OECD Guideline 421 in rats. Based on the results obtained from testing the parental NOAEL , the NOAEL for reproductive performance and the NOAEL for the F1 generation were determined to be 1000 mg/kg bw/day. In an OECD TG 414 a NOAEL for maternal toxicity and developmental toxicity including teratogenicity was determined to be 1000 mg/kg bw/day.The substance was not irritant or corrosive, to either skin or eye, in respective tests on rabbits. A test on guinea pigs revealed no skin sensitising properties. In a bacterial mutagenicity test (Ames test) and in a chromosome aberration assay on Chinese hamster V79 cells, no mutagenic/clastogenic effects were noted in the presence and absence of metabolic activation, even at toxic doses.  

 

Toxicokinetic Analysis of 2,2-Dimethyl-3-lauroyloxy-propanal 

The aldehyde 2,2-dimethyl-3-lauroyloxy-propanal has a calculated partition coefficient of logPow = 5.6479. Its water solubility is limited, due to oxidation and hydrolysis upon contact with water and the formation of a number of polar degradation products. A value of   < 0.3 mg/L was noted for the test item.   The estimated partition coefficient reveals that the compound may have the ability to penetrate skin. However, even if absorbed by skin, its toxicity is very low, as shown in the acute dermal toxicity study. Due to its low water solubility, the compound will most likely not solubilise in the stomach and thus probably not be absorbed in the GI-tract as such. Based on the data obtained in the water solubility study, the test item will most likely degrade rapidly upon entry of the body, forming several polar degradation products. These can be excreted quickly. This assumption is supported by the low acute oral toxicity and low toxicity observed in the 28-day toxicity study. However, small amounts of the test item have been probably absorbed after oral administration based on the results of the 90-day repeated dose study. In this study alterations in the spleen in the form of macroscopically enlargement associated with increases in spleen weight and accompanied by splenic hyperplasia in male and female rats were observed. Splenic alterations were fully reversible in male and female animals except the increase in spleen weight in female animals.

Application of 2,2-dimethyl-3-lauroyloxy-propanal to skin and eyes of rabbits did not cause any irritation or corrosion, nor where there any sensitising effects observed. In addition, topical application of high concentrations of compound did not cause any local effects or systemic toxicity.  

Absorbed by the body, following ingestion or passage through the skin, the aldehyde 2,2-dimethyl-3-lauroyloxy-propanal will degrade rapidly and distribute by systemic circulation, as will the degradation (oxidation and hydrolysis) products. Based on the results of the 90 -day repeated dose study, the spleen was identified as potential target organ. One of the most important pathway of aldehyde metabolism is oxidation to carboxylic acids by aldehyde dehydrogenases (Vasiliou et al., 2000). The enzymes involved in these detoxification reactions most probably belong to the category of aldehyde dehydrogenases known to be relatively substrate unspecific, but effective in protecting organisms from potentially harmful xenobiotics (Sladek, 2003). Other phase I metabolic reactions may include cytochrome P450 mediated transformations such as aldehyde reductions or aldehyde scissions. Following phase I metabolic reactions and/or chemical degradation, the formed metabolites are rendered more polar by phase II metabolism. Most likely the carboxylic acid metabolites are ultimately conjugated with glycine or glutamine, before being excreted in urine or bile.  

It is unlikely that metabolism will render the aldehyde compound more toxic, forming reactive products. This assumption is supported by results obtained in an in vitro Ames test and chromosome aberration test. In both assays no significant increases in toxicity were noted, in the presence of a rodent microsomal S9-fraction. This indicates that formation of reactive metabolites is rather unlikely.  

Based on the compound’s structure and associated physical-chemical characteristics, particularly its limited stability in water-based systems, the compound is hardly bioavailable as such and thus, bioaccumulation is not likely to occur. Absorbed or bioavailable compound most likely degrades and decomposition products are further metabolised and excreted or excreted as such. Formation of toxic metabolites is unlikely, based on the results of oral and dermal toxicity studies and two studies using isolated S9-fractions.

Description of key information

Based on the data obtained in the water solubility study, the test item will most likely degrade rapidly upon entry of the body, forming several polar degradation products. Aldehyde 2,2-dimethyl-3-lauroyloxy-propanal itself is expected to be oxidised by aldehyde dehydrogenases to the corresponding carboxylic acid. Most likely the carboxylic acid metabolites are ultimately conjugated with glycine or glutamine, before being excreted in urine or bile.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

General  

The aldehyde 2,2-dimethyl-3-lauroyloxy-propanal is formed during the hydrolysis of Sika Härter LJ, Sika Härter LH and Sika Härter LTJ. All three Sika Härter are hardeners for polyurethane moisture hardening adhesives and sealant. During the hardening process the hardeners are rapidly hydrolysed, forming the aldehyde 2,2-dimethyl-3-lauroyloxy-propanal and corresponding polyamines.  

Typically, the hardeners react with the polyurethane mass and become chemically bound components within the polymer matrix, irreversibly integrating the aldehyde. If not integrated in a polyurethane matrix, 2,2-dimethyl-3-lauroyloxy-propanal is prone to oxidation by air or hydrolysis in water. Principal oxidation product is 2,2-dimethyl-3-lauroyloxy-propanoic acid (a carbonic acid). Conversion of aldehyde to carbonic acid by air oxygen is slow and generally the process takes hours to days. Hydrolysis in water on the other hand, is a more rapid process and, as shown in the solubility study, so fast it even prevents the compound from reaching a solubility equilibrium. Thus, the compound is extremely unstable in water and no true water solubility could be determined. Besides the carbonic acid several other polar hydrolysis products (short-chain) were noted within minutes following contact with water.  

 

Toxicological Profile of 2,2-Dimethyl-3-lauroyloxy-propanal 

Based on the LD50-values ( > 2,000 mg/kg bw) from acute oral and acute dermal toxicity studies in rats, 2,2-dimethyl-3-lauroyloxy-propanal is of low acute toxicity. In a 28-day toxicity study a NOEL of 1000 mg/kg bw/day was observed. A NOAEL was determined to be 300 mg/kg bw/d in male and female rats in a 90-day repeated dose study. The reprotoxic properties of the test item were assessed in a study performed according to OECD Guideline 421 in rats. Based on the results obtained from testing the parental NOAEL , the NOAEL for reproductive performance and the NOAEL for the F1 generation were determined to be 1000 mg/kg bw/day. In an OECD TG 414 a NOAEL for maternal toxicity and developmental toxicity including teratogenicity was determined to be 1000 mg/kg bw/day. The substance was not irritant or corrosive, to either skin or eye, in respective tests on rabbits. A test on guinea pigs revealed no skin sensitising properties. In a bacterial mutagenicity test (Ames test) and in a chromosome aberration assay on Chinese hamster V79 cells, no mutagenic/clastogenic effects were noted in the presence and absence of metabolic activation, even at toxic doses.  

 

Toxicokinetic Analysis of 2,2-Dimethyl-3-lauroyloxy-propanal 

The aldehyde 2,2-dimethyl-3-lauroyloxy-propanal has a calculated partition coefficient of logPow = 5.6479. Its water solubility is limited, due to oxidation and hydrolysis upon contact with water and the formation of a number of polar degradation products. A value of   < 0.3 mg/L was noted for the test item.   The estimated partition coefficient reveals that the compound may have the ability to penetrate skin. However, even if absorbed by skin, its toxicity is very low, as shown in the acute dermal toxicity study. Due to its low water solubility, the compound will most likely not solubilise in the stomach and thus probably not be absorbed in the GI-tract as such. Based on the data obtained in the water solubility study, the test item will most likely degrade rapidly upon entry of the body, forming several polar degradation products. These can be excreted quickly. This assumption is supported by the low acute oral toxicity and low toxicity observed in the 28-day toxicity study. However, small amounts of the test item have been probably absorbed after oral administration based on the results of the 90-day repeated dose study. In this study alterations in the spleen in the form of macroscopically enlargement associated with increases in spleen weight and accompanied by splenic hyperplasia in male and female rats were observed. Splenic alterations were fully reversible in male and female animals except the increase in spleen weight in female animals.

Application of 2,2-dimethyl-3-lauroyloxy-propanal to skin and eyes of rabbits did not cause any irritation or corrosion, nor where there any sensitising effects observed. In addition, topical application of high concentrations of compound did not cause any local effects or systemic toxicity.  

Absorbed by the body, following ingestion or passage through the skin, the aldehyde 2,2-dimethyl-3-lauroyloxy-propanal will degrade rapidly and distribute by systemic circulation, as will the degradation (oxidation and hydrolysis) products. Based on the results of the 90 -day repeated dose study, the spleen was identified as potential target organ. One of the most important pathway of aldehyde metabolism is oxidation to carboxylic acids by aldehyde dehydrogenases (Vasiliou et al., 2000). The enzymes involved in these detoxification reactions most probably belong to the category of aldehyde dehydrogenases known to be relatively substrate unspecific, but effective in protecting organisms from potentially harmful xenobiotics (Sladek, 2003). Other phase I metabolic reactions may include cytochrome P450 mediated transformations such as aldehyde reductions or aldehyde scissions. Following phase I metabolic reactions and/or chemical degradation, the formed metabolites are rendered more polar by phase II metabolism. Most likely the carboxylic acid metabolites are ultimately conjugated with glycine or glutamine, before being excreted in urine or bile.  

It is unlikely that metabolism will render the aldehyde compound more toxic, forming reactive products. This assumption is supported by results obtained in an in vitro Ames test and chromosome aberration test. In both assays no significant increases in toxicity were noted, in the presence of a rodent microsomal S9-fraction. This indicates that formation of reactive metabolites is rather unlikely.  

Based on the compound’s structure and associated physical-chemical characteristics, particularly its limited stability in water-based systems, the compound is hardly bioavailable as such and thus, bioaccumulation is not likely to occur. Absorbed or bioavailable compound most likely degrades and decomposition products are further metabolised and excreted or excreted as such. Formation of toxic metabolites is unlikely, based on the results of oral and dermal toxicity studies and two studies using isolated S9-fractions.