Pyruvaldehyde

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Data from Glyoxal (CAS 107-22-2) as a structural analogon to pyruvaldehyde (methylglyoxal, CAS 78-98-8) were evaluated in a read across: Glyoxal 40% aqueous solution was tested for skin sensitization in the guinea pig maximisation test (GPMT) according to the OECD TG 406 (BASF AG, 1987). The first induction was intradermal, and the test substance was used as 20% solution in distilled water and in Freund´s adjuvant/ distilled water (1:1), respectively. The second induction was percutaneous occlusive and the test substance was applied unchanged. Two percutaneous occlusive challenges were conducted one week and 14 days after the first induction using a 10% solution of test substance in distilled water. Skin readings were performed after 24, 48 and 72 hours following each challenge.

Following inductions, the test animals treated with test substance formulation in Freund’s adjuvant/distilled water (1:1) and in distilled water, respectively showed skin lesions consisting of necrotic changes and distinct edema. One guinea pig died after the intradermal induction for unknown reasons.

Following challenges, no animals with positive skin reaction were found in the two negative control groups. As positive control, laboratory data from dinitrochlorobenzene tests conducted twice a year with the selected guinea pig strain were available that confirmed the sensitivity and validity of the test method and study. In the glyoxal 40% treated test group, 7/19 animals (i.e. 37%) showed positive skin reactions mostly consisting of distinct erythema after the first challenge, at reading time point 48 h; after the second challenge, 11/19 animals were still scored positive (i.e. 58%) as they displayed slight to distinct erythema. For both challenges, the percentage of animals exhibiting positive skin reaction was > 30%. The additional GPMT study (OTS, 1991) confirmed the sensitizing potential of glyoxal since the test substance caused delayed moderate hypersensitivity in male and female guinea pig. The sensitizing potential of Glyoxal was further confirmed and cross-sensitization was shown between glyoxal and formaldehyde, respectively glutaraldehyde in a guinea pig maximisation test conducted according to Magnusson and Kligman (Foussereau et al., 1992). In fact, in this study, groups of 30 female albino Dunkin-Hartley guinea pigs first were tested for Glyoxal, formaldehyde and glutaraldehyde sensitization, respectively followed by a testing for cross sensitization. The animals reacted positively when treated with Glyoxal alone, with 86% of test animals showing severe skin reactions after challenge. Testing for Glyoxal cross sensitization was also positive, resulting in 62% and 72% of animals with skin reaction for formaldehyde and glutaraldehyde, respectively (Foussereau et al., 1992). In a sensitisation test conducted according to the method of Buehler, glyoxal exhibited a potential to induce dermal sensitisation in guinea pig at concentrations of 1.25, 5 and 20%, and to ellicit responses to challenge concentrations of 0.3% and higher. Presence and degree of sensitisation here was found to be dependent upon induction and challenge concentration (OTS, 1988). Basketter and coworkers tested glyoxal in the LLNA test with femal CBA mice (Basketter DA 1999). The LLNA was conducted according to the standard protocol defined by Kimber and Basketter (Food and Chem. Toxicol. 30: 165-169, 1992). The test method was in principle similar to the OECD TG 429 (Skin Sensitisation: Local Lymph Node Assay). Groups of mice (n = 4) were treated by daily topical application for 3 consecutive days with 25 µL of one of three concentrations of the test chemical on the dorsum of each ear. Control mice were treated with vehicle alone in an identical manner. 5 days after the first topical application, all mice were injected iv with 250µL phosphate buffered saline (PBS) containing 20 µCi of [3H]methyl thymidine. The mice were killed 5 hours later and the draining auricular lymph nodes were excised and pooled for each experimental group. A single cell suspension of lymph node cells (LNC) was prepared by gentle disaggregation through 200 mesh stainless-steel gauze. Pooled LNC were pelleted by centrifugation, washed, and resuspended in 3 ml 5% trichloroacetic acid (TCA). After incubation overnight at 4°C, the precipitate was recovered by centrifugation, resuspended in 1 mL of 5% TCA and transferred to 10 mL scintillation fluid. Incorporation of [3H]methyl thymidine was measured by beta-scintillation counting. The proliferative response of LNC was expressed as mean radioactive disintegrations per minute per lymph node (dpm/node for each experimental group and as the ratio of [3H]methyl thymidine incorporation into LNC of test nodes relative to control nodes [test:control (T:C) ratio]. A chemical was regarded as a sensitizer in the LLNA if at least one concentration resulted in a T:C ratio of 3 or greater and the data were not incompatible with a biological dose response. Positive results were observed in the animals at each tested concentration (5%, 10% and 25%), with respective T:C ratios of 18.1, 13.6 and 12.2. Thus, In the murine Local Lymph Node essay (LLNA), the positive results confirmed that Glyoxal can be considered as a sensitizer.

The overall result of the studies presented is in accordance with the official R43 EU classification (Annex I of Directive 67/548/EEC in the EU chemical legislation). According to GHS (2005), Glyoxal 40% has to be classified into Category 1 “sensitizing”.

Migrated from Short description of key information:
Data from Glyoxal (CAS 107-22-2) as a structural analogon to pyruvaldehyde (methylglyoxal, CAS 78-98-8) were evaluated in a read across:
Glyoxal 40% aqueous solution caused skin sensitization in the guinea pig maximisation test (GPMT), Buehler Test and LLNA. Due to the apparent structural similarities between pyruvaldehyde and glyoxal, it can be assumed that the test item pyruvaldehyde has comparable sensitizing properties.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The test item has no structural alert indicative for respiratory sensitisation. In addition, no human data on respiratory sensitisation have been reported. The test item is considered not to induce respiratory sensitisation.

Migrated from Short description of key information:
Considered not to induce respiratory sensitisation.

Justification for classification or non-classification

Skin sensitisation

Based on the available read across data from glyoxal, the test item is clasified a skin sensitiser (R43) according to 67/548/EEC and Regulation (EC) No 1272/2008 (GHS, CLP; Class 1, H317: May cause an allergic skin reaction)

Respiratory sensitisation

Considered not to induce respiratory sensitisation.