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Toxicological information

Endpoint summary

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Administrative data

Description of key information

Skin sensitisation:

No study is available for skin sensitisation with sodium dichromate. However, based on the information on a structurally related hexavalent chromium substance (potassium dichromate), it was concluded using a category read-across concept, that ,like potassium dichromate, sodium dichromate is classified as skin sensitiser Category 1 with the signal word Warning and hazard statement H317: May cause an allergic skin reaction.

Respiratory sensitisation:

No study is available for respiratory sensitisation with sodium dichromate, since no suitable animal tests are available for the detection of respiratory sensitisation. However, based on the information on occupational asthma in humans with the a structurally related hexavalent chromium substance (potassium dichromate), it was concluded using a category read-across concept, that, like potassium dichromate, sodium dichromate is classified as respiratory sensitiser Category 1 with the signal word Danger and hazard statement H334: May cause allergy or asthma symptoms or breathing difficulties if inhaled.

Both classifications are in line with the legal classifications of sodium dichromate (Index number 024 -004 -00 -7).

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

No study is available for skin sensitisation with sodium dichromate. However, information on skin sensitisation testing in humans with potassium dichromate is available in literature, which can be found in IUCLID Section 7.10.4 Sensitisation data (humans). Using a category read-across concept, the information of a structurally related hexavalent chromium substance (potassium dichromate) can be used to determine the skin sensitisation potential of sodium dichromate.

Uter et al. (2009) presented an analysis of the current prevalences of skin sensitization to nickel, cobalt, and chromium from the European Surveillance System on Contact Allergies (ESSCA) network, covering 2009–2012, from 12 countries participating. Patch testing is performed and the maximum patch test reactions between day 3 and 5 (inclusive) were aggregated as the patch test outcome. In this testing series, potassium dichromate (0.5 % (pet-based) and 0.023 mg/m³(TRUE Test®) was one of the testes substances. The results showed that potassium dichromate was tested positive in skin sensitisation testing conducted in different countries (positive reaction varied from 1.5 % to 12. 1% in pet.-based tesing and from 3.7% to 4.3 % in TRUE Test®). Furthermore, a concomitant reactivity between nickel and chromium [OR: 2.4 (95%CI: 2.2–2.7)]; and between cobalt and chromium [OR: 11.9 (95%CI: 10.8–13.1)] is evident.

Rui et al. (2012) investigated the temporal trend of chromium contact sensitization between 1996 and 2010 in north-eastern Italy. 19088 consecutive patients were included in the study, which were patch tested with the European baseline series by use of Finn Chambers® on Scanpor®, and allergens from FIRMA.The tested allergens included potassium dichromate 0.5% pet. The authors showed that the overall prevalence of chromium sensitization dropped from 10.2% (1996–1998) to 4.6% (2008–2010) among women, and from 11.3% (1996–1998) to 5.9% (2008–2010) among men in north-eastern Italy.

The two references, as described above, provide some evidence that potassium dichromate has the potential of skin sensitisation. Furthermore, the EU RAR (2005) states that "skin sensitisation resulting from contact with Cr(VI) compounds is relatively common in humans working with the compounds. This has been demonstrated in patch testing of contact dermatitis patients and in investigations of various occupational groups. In addition, skin sensitisation potential has been clearly demonstrated in standard and modified guinea pig maximisation tests and in the mouse ear swelling test. Current understanding of the mechanism involved in the sensitisation indicates that Cr (III) is the ultimate hapten. Skin contact with Cr (VI) leads to penetration of Cr (VI) into the skin where it is reduced to Cr (III). There is some evidence for cross-reactivity between Cr (III) and Cr (VI); Cr(VI)-sensitised subjects may also react to Cr (III). Overall, it is not possible to reliably determine a threshold for either induction or challenge in an exposed population using the available data".

Based on the information on the skin sensitisation poential with the a structurally related hexavalent chromium substance (potassium dichromate), as presented above, it was concluded using a category read-across concept, that like potassium dichromate, sodium dichromate is also sensitising to the skin and should be classified as such.

*References:

- EU RAR (2002): CHROMIUM TRIOXIDE, SODIUM CHROMATE, SODIUM DICHROMATE, AMMONIUM DICHROMATE AND POTASSIUM DICHROMATE. Vol. 53. EUR 21508.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

No suitable animals tests are available for the detection of respiratory sensitisation. However, information on occupational asthma in humans with potassium dichromate is available in literature, which can be found in IUCLID Section 7.10.4 Sensitisation data (humans). Using a category read-across concept, the information of a structurally related hexavalent chromium substance (potassium dichromate) can be used to determine the skin sensitisation potential of sodium dichromate.

Fernandez-Nieto et al. (2006) described four male patients with work-related asthma due to metallic salts. Two subjects came from factories where potassium dichromate and nickel sulfate were used for electroplating, another subject worked in a cement factory (exposed to potassium dichromate), and one was a manual metal-arc welder exposed to different metal fumes, including nickel and chromium. All subjects were ex-smokers or non-smokers and only one was atopic. The time since exposure cessation ranged between 1 and 4 months. A bronchial challenge test with potssium dichromate (0.001, 0.01, 0.1, 1, and 1 0 mg/mL in normal saline) was performed with the four participants. The bronchial challenge test with potassium dichromate elicited asthmatic reactions at a concentration of 0.01 mg/mL in one subject and at 10 mg/mL in the remaining workers. The test elicited late asthmatic reactions (LAR) in two workers, one subject had an early asthmatic reaction (EAR), and another subject showed a dual asthmatic reaction (DAR). Lastly, the bronchial challenge test with the metallic salt in two unexposed asthmatic subjects were negative.

Walters et al. (2012) describe five male employees (two ex-smokers; three never smoked) of a medium-sized manufacturer of precision engineering parts who were toolmakers or grinders by trade, which presented work-related respiratory symptoms. The five workers were investigated using methacholine reactivity, two-hourly peak flow measurements, spirometry, fractional exhaled nitric oxide, and after a subsequent workplace visit specific inhalation challenge (SIC) tests. These were performed via a nebuliser over three exposures totalling 32–35 min for potassium dichromate (2 mg/mL). Three cases of occupational asthma due to chromium salt were diagnosed by serial peak-expiratory flow measurements and specific inhalation challenge testing.

Furthermore, Walters et al. (2012) carried out an epidemiological investigation with 62 workers. Participants answered a detailed, self-administered questionnaire, designed to detect occupational lung disease. Urine chromium and cobalt excretion, spirometry and exhaled nitric oxide measurements were taken. Those with possible, probable or definite non- occupational asthma or occupational asthma, after questionnaire, were invited to undertake two-hourly peak flow measurements and received specialist follow-up. Sixty-one per cent of employees were working in higher metalworking fluid (MWF) exposure areas. Ninety per cent of workers had urinary chromium excretion indicating occupational exposure. Sixty-six per cent of workers reported active respiratory symptoms, although there were no significant differences between exposure groups. Two further workers with probable occupational asthma were identified and had significantly higher urinary chromium and cobalt concentration than asymptomatic controls. Eighteen cases of occupational rhinitis were identified, with significantly raised urinary chromium concentration compared with asymptomatic controls.

Bright et al. (1997) described seven subjects (4 males and 3 females) that had been exposed to chrome and nickel fumes from electroplating. A diagnosis of occupational asthma was made from a history of asthma with rest day improvement and confirmed by specific bronchial provocation testing with potassium dichromate. Two workers had isolated immediate reactions, one a late asthmatic reaction, and four a dual response following exposure to nebulised potassium dichromate at 1–10 mg/mL.

The three references, as described above, give some indication that potassium dichromate can produce occupational asthma in humans. Furthermore, the ATSDR (2012) states that "chromium-induced asthma may occur in some sensitized individuals exposed to elevated concentrations of chromium in air, but the number of sensitised individuals is low and the number of potentially confounding variables in the chromium industry is high." In addition, the EU RAR (2005) mentions that "a number of case reports, mainly within the chrome plating industry, provide evidence that inhaled Cr (VI) can cause asthma, although the total number of reported cases is small in relation to the number of workers potentially exposed. Positive findings are available from several well-conducted bronchial challenge tests. No information is available on the dose-response relationships for induction of the hypersensitive state or elicitation of an asthmatic response in hypersensitive individuals. The available case reports and evidence from well-conducted bronchial challenge tests, show that inhalation of Cr (VI) compounds can cause occupational asthma. As with skin, Cr (VI)- sensitised subjects may react to Cr (III). It is not possible to determine a no-effect level or exposure-response relationship for induction or elicitation of occupational asthma."

Based on the information on occupational asthma with the a structurally related hexavalent chromium substance (potassium dichromate), as presented above, it was concluded using a category read-across concept, that like potassium dichromate, sodium dichromate is also sensitising to the respiratory tract and should be classified as such.

*References:

- EU RAR (2002): CHROMIUM TRIOXIDE, SODIUM CHROMATE, SODIUM DICHROMATE, AMMONIUM DICHROMATE AND POTASSIUM DICHROMATE. Vol. 53. EUR 21508.

- ATSDR (2012): Toxicological profile for chromium.

Justification for classification or non-classification

Skin sensitisation:

According to the classification criteria of CLP regulation (EC) 1272/2008 and subsequent regulations, sodium dichromate should be classified as skin sensitiser. This is in line with the legal classification of sodium dichromate with the index number 024 -004 -00 -7. According to the legal classification sodium dichromate is classified as skin sensitisier Categroy 1 (H317: May cause an allergic skin reaction).

Respiratory sensitisation:

According to the classification criteria of CLP regulation (EC) 1272/2008 and subsequent regulations, sodium dichromate should be classified as respiratory sensitiser. This is in line with the legal classification of sodium dichromate with the index number 024 -004 -00 -7. According to the legal classification sodium dichromate is classified as respiratory sensitisier Categroy 1 (H334 - May cause allergy or asthma symptoms or breathing difficulties if inhaled).