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Description of key information

C10-13 chlorinated paraffins (of varying chain length and degree of chlorination) are of very low acute toxicity in animal studies, with some signs of systemic toxicity seen in rats and mice administered oral doses of 13 and 27 g/kg bw, respectively, but no signs of systemic toxicity in rats following 1 h exposure to vapours of 3.3 g/m3 and greater or with a dermal dose of 2.8 g/kg bw. Acute LD50s of greater than 4 and 2.8 g/kg bw following oral and dermal exposures, respectively, and LC50s of more than 3300 mg/m3 (3.3 mg/L), have been reported.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
4 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
3 300 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
2 800 mg/kg bw

Additional information

No relevant human data is currently available.

Acute oral toxicity

In good quality NTP studies, groups of F344/N rats and B6C3F1 mice (5/sex/dose) were given single doses of a C12 chlorinated paraffin (60% chlorination) by stomach tube and observed for abnormal clinical signs twice daily for up to 15 days. The chlorinated paraffin was administered in corn oil at dose levels of 816, 1632, 3400, 6800 and 13,600 mg/kg bw in rats and of 1632, 3264, 6800 and 13,600 mg/kg bw at a dose volume of 20 ml/kg and at 27,200 mg/kg bw undiluted in mice. No deaths were observed at any dose during the study period. All animals were inactive and ataxic after dosing. In rats, diahrroea was seen in all males and all but the lowest dose females lasting between 2 and 6 days. Ruffled fur was seen in all mice on days 2 to 6 after dosing (NTP, 1986).

As summarised in the final RAR (EU, 2000), several other studies have been conducted on C10-13 paraffins which were 40 to 70% chlorinated. In all of these studies groups of three male and three female rats were treated by gavage with a range of maximum doses of 4 to 13 g/kg bw chlorinated paraffin (containing up to 5% epoxy stabilisers with various additives). Rats were observed for 7 days after treatment when macroscopic examinations were conducted. With the exception of one study, no deaths occurred. The death occurred in one rat treated with 13 g/kg bw with a 63% chlorinated paraffin (ICI, 1974). Signs of toxicity in the moribund and surviving animals were also more extreme in this study and included coma, laboured breathing and tremors. Signs of toxicity in the majority of studies occurred with the lowest doses tested, from approximately 2 g/kg, and included piloerection, urinary incontinence and lethargy. Recovery, when reported, was usually complete by day 7. Macroscopic examination revealed "minimal signs of stress" in the spleen (with a 50% chlorinated paraffin, unpublished reference 59, 1968), blotchy or pale liver with slight fatty changes and inflamed stomach (with 69 and 40% chlorinated paraffin, unpublished references 61, 1965 and 57, 1966). Overall, the chlorinated paraffins tested were of very low oral toxicity following a single dose and the intensity and nature of those effects that were observed were independent of degree of chlorination.

According to a published paper (Birtley et al. 1980), which summarises several or all of the studies mentioned above, groups of 3 or more male and/or female Wistar rats were given single doses of various C10 -13 chlorinated paraffins (with extent of chlorination varying from 41 to 70%) by stomach tube and observed for abnormal clinical signs for up to 14 days. At the end of this observation period, animals were autopsied and selected tissues/organs were examined histologically and microscopically. Dose levels of chlorinated paraffins used varied from 0.5 to 10 g/kg bw, administered with or without a vehicle such as olive oil. A total of 14 experiments were carried out with the C10 -13 chlorinated paraffins. No mortalities were observed for any of the tested chlorinated paraffins, although various abnormalities were noted, including certain adverse clinical signs (piloerection, muscular incoordination and urinary/fecal incontinence) and histopathological changes (including hepatocellular vacuolation and focal necrosis in the liver and cloudy swelling of inner cortical cells in the kidneys). It was noted that the toxic effects were slight and that the clinical signs generally disappeared within 7 days. The limitations in reporting do not allow the observed effects to be attributed to any specific chlorinated paraffin sample or to ascertain at what dose level(s) the effects occurred. However, the acute oral LD50 in these studies is reported to be greater than 4 g/kg bw.

Acute inhalation toxicity

Cereclor 50 HS (a 50% chlorinated, short-chain paraffin; presumably C10-13) was tested for acute inhalation toxicity in rats at a vapour concentration of 48.17 g/m3 for 1 h. No deaths were reported and only slight nose and eye irritation were seen. Recovery occurred "soon" after exposure and remained normal throughout the [unspecified] observation period. The 1 h acute inhalation LC50 for Cereclor 50 HS is greater than 48.17 g/m3 (48.17 mg/L).

No deaths and no other signs of toxicity were observed in rats exposed to air containing Chlorowax 500C (a C12 chlorinated paraffin; 59% chlorination) at 3300 mg/m3 (3.3 mg/L) for 1 h, therefore the 1 h acute inhalation LC50 value can be considered as greater than 3300 mg/m3 (3.3 mg/L). No further details are given in an early US EPA review (Howard et al. 1975) apparently citing a personal communication with industry (Diamond Shamrock Chem. Co. 1975), or in the final RAR on SCCPs (EU, 2000).

Acute dermal toxicity

According to the final RAR on SCCPs (EU, 2000), a C10-13 chlorinated paraffin (52% chlorination) was tested for acute dermal toxicity at 2.5 ml/kg bw (about 2.8 g/kg bw) in an well-conducted study (ICI, 1971). When applied undiluted, under an occlusive dressing, to groups of 3 rats for 24 h, local signs of irritation (slight erythema and slight slight desquamation) were seen at the application site at 3 and 7 days post-application. No deaths or other signs of systemic toxicity were reported in the treated rats. The acute dermal LD50 of this C10-13 chlorinated paraffin can be considered as greater than 2.5 ml/kg bw (about 2.8 g/kg bw).

The acute dermal LD50 value for Chlorowax 500C (a C12 chlorinated paraffin; 59% chlorination) was reported to be greater than 10 ml/kg bw (approximately 13.5 g/kg bw) in the rabbit. The test material was apparently applied occluded for 24 h, and the animals observed for 14 days. No further details are given in an early US EPA review (Howard et al. 1975) apparently citing a personal communication with industry (Diamond Shamrock Chem. Co. 1975), or in the final RAR on SCCPs (EU, 2000).

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

ICI (1974). ICI Report CLT/T/962, 01.12.74 (cited in EU, 2000).

Justification for classification or non-classification

The acute oral LD50 of various C10 -13 chlorinated paraffins (40 -70% chlorination) is reported to be greater than 4 g/kg bw, the acute LC50 of two C10-13 chlorinated paraffins (50 and 59% chlorination) was more than 3300 mg/m3 (3.3 mg/L), and the acute dermal LD50 of two C10-13 chlorinated paraffins (52 and 59% chlorination) can be considered as greater than 2.5 ml/kg bw (about 2.8 g/kg bw). Therefore, under the condiions of these studies, SCCPs would not be classified as acutely toxic by any route of exposure according to EU CLP or DSD regulations.