Sulfuric acid, mono-C16-18-alkyl esters, sodium salts

Endpoint summary

Description of key information

Oral LD50 (OECD guideline 401), rat = 4010 mg/kg bw
Dermal LD50 (OECD guideline 402), rabbit > 2000 mg/kg bw (limit test) 
Acute toxicity by inhalation was not tested according to REGULATION (EC) No 1907/2006, Annex VIII, Section 8.5, Column 2.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

4 010 mg/kg bw

Quality of whole database:

The whole data base is conclusive and of high quality.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

Acute toxicity by inhalation was not tested according to REGULATION (EC) No 1907/2006, Annex VIII, Section 8.5, Column 2.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

The whole data base is conclusive and of high quality.

Additional information

There are two acute oral toxicity studies for C16-18AS Na (CAS 68955-20-4) available. No data on acute dermal toxicity are available for C16-18AS Na (CAS 68955-20-4). Therefore this endpoint is covered by read across to structurally related alkyl sulfates (AS) for weight-of-evidence approach, i.e. C10-16AS NH4 (CAS 68081-96-9), C10-16AS Mg (CAS 68081-97-0) and C12-13AS K (CAS 91783-22-1). In addition the read across approach was chosen for acute toxicity via the oral route to support the results of the two available studies with for C16-18AS Na (CAS 68955-20-4).The possibility of a read-across to other alkyl sulfates in accordance with Regulation (EC) No 1907/2006 Annex XI 1.5. Grouping of substances and read-across approach was assessed. In Annex XI 1.5 it is given that a read-across approach is possible for substances, whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity. The AS reported within the AS category show structural similarity. The most important common structural feature of the category members is the presence of a predominantly linear aliphatic hydrocarbon chain with a polar sulfate group, neutralized with a counter ion. This structural feature confers the surfactant properties of the alkyl sulfates. The surfactant property of the members of the AS category in turn represent the predominant attribute in mediating effects on mammalian health. Therefore, the AS of the AS category have similar physico-chemical, environmental and toxicological properties, validating the read across approach within the category. The approach of grouping different AS for the evaluation of their effects on human health and the environment was also made by the OECD in the SIDS initial assessment profile [1] and by a voluntary industry programme carrying out Human and Environmental Risk Assessments (HERA [2]), further supporting the read across approach between structurally related AS.

Acute oral toxicity

One acute oral study was conducted with C12-18AS Na (CAS 68955-19-1, analytical purity 25%) on Cox CD rats (P&G, 1974). The test substance was applied to 10 animals per sex per group at doses of 2500, 3500, 4900 and 6850 mg/kg bw via gavage. The post observation period comprised 14 days. Following mortalities were observed within the different dose groups: 0/10, 5/10, 6/10 and 10/10. Clinical signs of toxicity comprised of slight to moderate decreased motor activity and respiratory rate, blanching, abdominal griping and diarrhea at 2500 mg/kg bw, slight haemorrhagic rhinitis which persisted up to seven days post treatment at 3500 and 4900 mg/kg bw and of slight loss of corneal reflex and pupillary responses at 6850 mg/kg bw. No findings were observed upon necropsy. The LD50 was given as 4010 mg/kg bw based on the active ingredient in the study report.

The first available study with C16-18AS Na (CAS 68955-20-4, analytical purity 55%) was conducted similar to OECD guideline 401 as a limit test at 2000 mg/kg bw on 5 Wistar rats per sex per dose (Potokar, 1987). The animals were treated via gavage and the post observation period comprised of 14 days. No mortalities occurred. Clinical signs of toxicity comprised of decreased motility in males and salivation after dosing. Upon necropsy no treatment related findings were observed. Thus, the LD50 was greater than 2000 mg/kg bw based on the test substance and greater than 1100 mg/kg bw based on the active ingredient.

The second study with pure C16-18AS Na (CAS 68955-20-4, analytical purity 94.3%) was conducted according to OECD guideline 401 presumably as a limit test at 2000 mg/kg bw on 10 Wistar rats per sex per dose. Only limited data on the experimental phase are available. No route of application was given but the volume administered was 10 mL/kg bw indicating an application via gavage. The LD50 within this study was greater 2000 mg/kg bw based on the test substance and although the analytical purity is above 94% this was calculated based on active ingredient to yield an LD50 greater 1886 mg/kg bw.

In conclusion the data justify a non-classification of C16-18AS Na (CAS 68955-20-4) for oral acute toxicity.

Acute dermal toxicity

Regarding the acute dermal toxicity four relevant studies are available for the read-across substances C10-16AS NH4 (CAS 68081-96-9), C10-16AS Mg (CAS 68081-97-0), C12-13AS K (CAS 91783-22-1) and C8AS Na (CAS 142-31-4).

The key study was conducted with C8AS Na (CAS 142-31-4) according to OECD Guideline 402 (BASF, 2012). 5 Wistar rats per sex were treated with 2000 mg/kg bw under semi occlusive conditions for 24 h. No mortality occurred, no sign of systemic toxicity and of local irritation was observed.

The study conducted with C10-16AS NH4 (CAS 68081-96-9) was performed as limit test conducted similar to OECD Guideline 402 with 3 male and 3 female New Zealand White rabbits (Frank, 1975). The test substance (analytical purity 25.1%) was applied at 2000 mg/kg bw for 24 h under occlusive conditions. No mortalities occurred. Clinical signs of toxicity comprised of severe erythema and slight eschar formation at 24 h, necrosis by day 2–14 with sloughing of the skin by day 8–14 and hyper-pigmentation of new skin by day 14. No signs of systemic toxicity were observed. Hence, the LD50 value is greater than 2000 mg/kg bw based on the test material and greater than 500 mg/kg bw based on the active ingredient.

The study conducted with C10-16AS Mg (CAS 68081-97-0) was performed as limit test conducted similar to OECD Guideline 402 with 3 male and 3 female New Zealand White rabbits (Frank, 1975). The test substance (analytical purity 23.5%) was applied at 2000 mg/kg bw for 24 h under occlusive conditions. No mortalities occurred. Clinical signs of toxicity comprised of severe erythema and eschar formation at 24 h, necrosis by Day 5–21 and necrotic tissues sloughed and leaving skin hyper-pigmented at Day 21. Hence, the LD50 value is greater than 2000 mg/kg bw based on the test material and greater 500 mg/kg bw based on the active ingredient.

Another study similar to OECD Guideline 402 was performed with C12-13AS K (CAS 91783-22-1) on three male and three female New Zealand White rabbits (Benedict, 1978). Both sexes were dosed at 2000 mg/kg bw (analytical purity 25%) under occlusive conditions for 24 h. No mortalities occurred during the conduct of the study. Findings within this study comprised of moderate to severe erythema, edema, and atonia, desquamation and fissuring by day 6 and eschar formation and exfoliation. Based on the above mentioned findings the LD50 is greater than 2000 mg/kg bw based on the test material and greater 500 mg/kg bw based on the active ingredient.

Within the studies mentioned above no mortalities or signs of systemic toxicity occurred after dermal application of alkyl sulfates with varying carbon chain length. Taken into account the generally low toxicity after oral application and the low dermal absorption rate of alkyl sulfates (approx. 1%) this result was expected. In agreement, no classification for acute dermal toxicity is required. For details on absorption please see section Toxicokinetics, metabolim and distribution.

In conclusion the data justify a non-classification of C16-18 AS Na (CAS 68955-20-4) for dermal acute toxicity.

Acute inhalation toxicity

No studies for acute inhalation toxicity are available. However, testing the potential of acute toxicity via inhalation route of C16-18ASNa (CAS 68955-20-4) is considered to be not justified. According to Regulation (EC) No 1907/2006, Annex VIII, Section 8.5, Column 2, in addition to the oral route (8.5.1), for substances other than gases, the information mentioned under 8.5.2 to 8.5.3 shall be provided for at least one other route. As information under 8.5.3 (dermal route) is provided, the requirement is fulfilled by using the most appropriate route of exposure.

AS is mainly used in liquid media and due to its very low vapour pressure [2] inhalation is not viewed as a significant route of exposure.Inhalation of AS may occur by inhalation of aerosols generated by spray cleaners or by inhalation of detergent dusts (e.g. washing powder). Taken into account that the acute toxicity of AS is generally low no further information on acute toxicity is expected by testing for acute inhalation toxicity as the predominant effect will comprise of local irritant effects rather than systemic toxicity.

[1] SIDS initial assessment profile, (2007);
http://www.aciscience.org/docs/Alkyl_Sulfates_Final_SIAP.pdf

[2] (HERA Draft report, 2002);
http://www.heraproject.com/files/3-HH-04-%20HERA%20AS%20HH%20web%20wd.pdf

Justification for selection of acute toxicity – oral endpoint
Scientifically reliable study.

Justification for selection of acute toxicity – dermal endpoint
Reliable OECD Guideline study.

Justification for classification or non-classification

The available data on acute oral and dermal toxicity do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.