Alkanes, C10-13, chloro

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The potential of C10-13 chlorinated paraffins (50 -56% chlorination) to produce skin sensitisation in guinea pigs has been assessed using the Magnusson and Kligman method (which involves injection of Freund's Complete Adjuvant (FCA), followed by dermal induction and then dermal challenge with the test substance). All three unpublised studies are reported in the final RAR (EU, 2000) as well-conducted and performed according to modern protocols and using suitable induction times. In the first, animals were challenged with undiluted C10 -13 paraffin (assumed to be approximately 50% chlorinated) and evaluated after 24 hours. 2/20 showed marked diffuse redness and 1/20 showed slight redness and dryness. When the same animals were re-challenged 1 week later, no skin reactions were seen. No skin reactions were seen in the control group. In conclusion, the paraffin tested did not induce skin sensitisation in guinea pigs (Huels, 1988). In the second, animals were challenged with undiluted C10 -13 paraffin (56% chlorinated) and evaluated after 24 and 72 hours. 1/20 test animals showed "hardly perceptible" erythema after 24 hours, and 1/20 test animals (and 1/20 controls) showed "clearly defined" erythema and "slight" oedema after 72 hours (Hoechst, 1983). In the third, animals were challenged with undiluted C10 -13 chlorinated paraffin (56% chlorinated). 5/20 (25%) showed "clearly defined" erythema and a further 2 (10%) showed "slight, hardly perceptible" erythema. Upon rechallenge two weeks later, 4/20 (20%) showed "clearly defined" erythema and a further 4 (20%) showed "slight, hardly perceptible" erythema and slight oedema. No animals in the control group showed any evidence of a skin reaction. The study authors concluded that these results implicate C10-13 chlorinated paraffin (56% chlorinated) as a skin sensitiser in guinea pigs (Hoechst, 1984). However, the RAR (EU, 2000) concludes that as "less than 30% of the test group showed a clear reaction and the possibility that the epoxide stabiliser was responsible for producing the skin reactions", this study is not considered to provide sufficient evidence that this C10 -13 chlorinated paraffin (56% chlorinated) should be classified as a skin sensitiser

Another three briefly reported unpublished studies have been conducted which used similar, but not modern, protocols as briefly described above (cited in the EU, 2000). In the first, undiluted C10-13, 52% chlorinated paraffin was applied to the ears of 6 guinea-pigs on three successive days. Slight erythema was noted when challenged four days later with undiluted paraffin applied to the animal flanks. However, it was not stated how many animals showed such a reaction, but it was noted that four control animals also showed slight erythema at challenge. Despite the lack of detail it is clear that the SCCPs tested did not elicit a sensitisation response in this study. The authors considered that the paraffin was "irritant but not a strong sensitiser". This phrase was used in another unpublished summary when a 50% chlorinated paraffin was tested, apparently using the same protocol. No details were given, including the carbon chain length of the SCCP (Cereclor 50HS). The only information given was the conclusion which stated that the substance tested was "not a strong sensitiser". In view of use of this phrase it is impossible to draw any conclusions from this study with respect to skin sensitising potential. The third unpublished study to use the ear/flank protocol apparently found no signs of erythema at challenge with up to 10 % C10-13, 50% chlorinated paraffin. However, there is no information provided in the report to indicate if the challenge concentration was sufficient to stringently test for skin sensitisation, therefore no conclusions can be drawn from this study.

Application of an unspecified amount of Chlorowax 500C (a C12 chlorinated paraffin; 59% chlorination) to the skin of 200 male and female subjects evidently showed no skin sensitising potential (Howard et al. 1975). In an early study on cutting fluid coolants, 134 non-exposed employees and 75 exposed employees were patch tested with various constituents of the cutting fluids including chlorinated paraffins (Menter et al., 1975). No positive reactions were obtained with any of the constituents although the authors themselves suggested that the tests were not sufficiently stringent. A more recent study reported that positive skin reactions to chlorinated paraffin constituents were obtained in patch tests conducted on 4 employees suffering from scaly eczema, who had had occupational exposure to cutting oils (English et al., 1986; cited in EU, 2000 but no reference given). However, the paper concluded that the reaction was due to an additive in the cutting oil, rather than to the chlorinated paraffin.

Overall, the animal and human studies suggest that SCCPs do not have the potential to be skin sensitisers.

Reference (for which no ESR has been created - please move to reference list in CSR)

Menter P. et al. (1975). Patch testing of coolant fractions. J. Occupational Med., 17(9), 565-568 (cited in EU, 2000).

Migrated from Short description of key information:
A number of guinea pig maximisation tests, using diluted and undiluted C10-13 chlorinated paraffins (50 to 56% chlorination), have been performed. No consistent evidence of a skin sensitisation potential was reported in these tests, and no evidence was seen in limited human studies. The lack of reports of skin sensitisation to this widespead industrial substance suggests that SCCPs do not have the potential to be skin sensitisers.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No direct information is available from studies in humans or animals on respiratory sensitisation. However, in view of the widespread use of these substances, the absence of any reports suggests that SCCPs are not respiratory sensitisers. Their unreactive nature and the lack of skin sensitisation potential lends added support to this view (EU, 2000).

Migrated from Short description of key information:
There is no direct information available on the potential for SCCPs to produce respiratory sensitisation in animals or humans. However, in view of the widespread use of these substances, the absence of any reports suggests that SCCPs are not respiratory sensitisers. Their unreactive nature and the lack of skin sensitisation potential lends added support to this view

Justification for classification or non-classification

C10 -13 chlorinated paraffins (50 -56% chlorination) did not induce consistent evidence indicative of skin sensitisation in guinea pigs in several studies (or in limited human studies), and the prevalence was less than 30%, therefore no classification or labelling with respect to skin sensitisation would be required under EU CLP or DSD regulations.