Tricobalt dicitrate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Additional information:

There are no data available on skin sensitisation of Tricobalt dicitrate. However, there are reliable data available for structurally related cobalt compounds. Thus, read-across was conducted based on structural analogues.

Cobalt(II)chloride hexahydrate caused positive reactions in a modified guinea pig maximization test (GMPT) (Wahlberg and Boman, 1978). The test item sensitised 100% of the test animals at the highest challenge dose (0.78% Tricobalt dicitrate; recalculated value, equivalent to 1% cobalt(II)chloride hexahydrate) tested 25 hours after removal of the Finn chambers. The percutaneous absorption rate of cobalt(II)chloride hexahydrate through normal skin is obviously sufficient to induce contact allergy.

Ikarashi et al. (1992) showed a sensitising potential of cobalt(II)chloride hexahydrate in a local lymph node assay (LLNA) conducted similar to OECD guideline 429. Repeated exposure to 5% (equivalent to 5.23% cobalt hydrogencitrate, recalculated value) for three consecutive days induced an increase of LNC proliferative response in the draining lymph node of mice and resulted in a total stimulation index of 4.54.

In conclusion, reliable studies using different protocols, either GPMT or LLNA, demonstrated that cobalt(II)chloride hexahydrate is a skin sensitiser in guinea pigs and mice. In humans, dermal exposure have been also observed to result in sensitisation to soluble cobalt salts. Contact allergy was reported in 22 of 223 (9.9%) nurses who were tested with a patch test of 1% cobalt(II)chloride (Kiec-Swierczynska and Krecisz, 2000), as well as 16 of 79 (20.3%) of examined dentists (Kiec-Swierczynska and Krecisz, 2002). Numerous human data also show that soluble cobalt salts are skin sensitisers (for example Kanerva et al., 1988; Goh et al., 1986; Alomar et al., 1985).

References:

Kiec-Swierczynska M and Krecisz B, 2002, Allergic contact dermatitis in dentists and dental nurses. Exogenous Dermatology. 1(1): 27 -31

Kanerva L et al., 1988, Occcupational skin disease in Finland, International Archives of Occupational and Environmental Health, 60: 89 -94

Goh et al., 1986, Occupational dermatitis in a prefabrication construction factory. Contact dermatitis, 15: 235 -240

Alomar A et al., 1985, Occupational dermatosis from cutting oils. Contact dermatitis, 12:129 -138

Migrated from Short description of key information:
The read-across substance cobalt(II)chloride hexahydrate was sensitising in the guinea pig maximization test as well as in the local lymph node assay. Based on the analogy approach, Tricobalt dicitrate is also expected to be a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Additional information:

There are no data available on respiratory sensitisation of Tricobalt dicitrate. However, there are human case reports for structurally related cobalt compounds. Thus, read-across was conducted based on structural analogues.

The available case reports reveal that soluble cobalt salts are capable of inducing hypersensitive reactions in the respiratory tract after inhalation exposure. These hypersensitive reactions include e. g. respiratory irritation, asthma, wheezing, pneumonia.

Shirakawa et al. (1989) reported that inhalation of cobalt(II)chloride aerosols can provoke an asthmatic attack in sensitised individuals. Inhalation exposure to cobalt salts among glass bangle workers resulted in decreases in ventilatory function relative to the control workers (Rastogi et al., 1991). Numerous human data also show that soluble cobalt salts are respiratory sensitisers (for example Roto, 1980; Swennen et al., 1993; Kusaka et al., 1996a, 1996b; Ruokonen et al., 1996; Linna et al., 2003).

References:

Roto P, 1980, Asthma, symptoms of chronic bronchitis and ventilatory capacity among cobalt and zinc production workers. Scand J Work Environ Health 6: 1 -49

Swennen B et al., 1993, Epidemiological survey of workers exposed to cobalt oxides, cobalt salts and cobalt metal. British Journal of Industrial Medicine, 50: 835 -842

Kusaka Y et al., 1996a, Epidemiological study of hard metal asthma. Occup Environ Med 53: 188 -193

Kusaka Y et al., 1996b, Decreased ventilatory function in hard metal workers. Occup Environ Med 53: 194 -199

Ruokonen EL et al., 1996, A fatal case of hard-metal disease. Scand J Work Environ Health 22:62 -65

Linna A et al., 2003, Respiratory health of cobalt production workers. Am J Ind Med 44: 124 -132

Migrated from Short description of key information:
Case reports evidence the respiratory sensitisation by soluble cobalt salts in humans. Based on the analogy approach, Tricobalt dicitrate is also expected to be a respiratory sensitiser.

Justification for classification or non-classification

There are no data available on skin or respiratory sensitisation on Tricobalt dicitrate. However, there are reliable data available for structurally related compounds. Thus, read-across was conducted based on structural analogues.

Skin sensitisation:

DSD: R43

CLP: Skin sensitisation category 1

Respiratory sensitisation:

DSD: R42

CLP: Respiratory sensitisation category 1