Copper dichromium tetraoxide

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

other: Review of literature studies

Adequacy of study:

supporting study

Study period:

Variable

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Critical studies are reported in summary form.

Data source

Reference

Reference Type:

review article or handbook

Title:

The toxicity of chromium and inorganic chromium compounds

Author:

Health and Safety Executive

Year:

1989

Bibliographic source:

HSE Toxicity review 21

Materials and methods

Study type:

other: Review of literature studies

Endpoint addressed:

carcinogenicity

Test guideline

Qualifier:

no guideline available

Deviations:

not applicable

Principles of method if other than guideline:

The HSE review summarises the available literature studies.

GLP compliance:

no

Remarks:

: not applicable

Test material

Test material information

Constituent 1

Reference substance name:

Chromium (III) compounds

IUPAC Name:

Chromium (III) compounds

Details on test material:

The review includes studies of exposure to various chromium (III) compounds including chromium (III) oxide. It is noted that exposure to chromium (VI) compounds is a confounding factor in many studies.

Method

Type of population:

occupational

Details on exposure:

The process termed chromate production consists of milling chromite ore (containing chromium in a trivalent, very poorly water soluble form), and then roasting the ore in the presence of sodium carbonate to produce sodium chromate (containing chromium in the hexavalent, highly water soluble form). Sodium chromate is then acidified to produce sodium dichromate. During periods covered by epidemiological studies, workers have been exposed to various forms of chromium, differing in valency, chemical composition and water solubility.

Stainless steel (SS) welding fumes can be produced by two processes: manual metal arc (MMA) and metal inert gas (MIG) which differ in the amount and form of chromium present. SS-MMA welding fumes contain 0.5-5% chromium with 50-90% of the total chromium in the fumes present as water-soluble hexavalent chromates. SS-MIG welding fumes contain 8-16% chromium with 98-99% of the total chromium present as very poorly water soluble chromium (III) oxide or metallic chromium. However, a small amount of Cr (VI) is detectable in SS-MIG welding fume particles.

Results and discussion

Results:

From the few studies available, there is no evidence that occupational exposure to chromium (III) compounds has resulted in cancer in humans.

Any other information on results incl. tables

Studies of chromate production workers

Several mortality studies have been conducted on workers in some or all of the seven chromate production plants in the USA. These studies show a very high incidence of deaths from cancer of the respiratory tract among such workers. There are indications that the incidence of respiratory tract cancer has declined considerably among workers beginning employment at the plants in more recent times. However, from the information available, it is not possible to determine whether there is still an increased incidence of deaths from respiratory tract cancer among the current workforce. It is also not possible to attribute the high cancer mortality to particular work activities, or to specific forms or atmospheric levels of chromium. Suggestions have also been made of increased incidences of cancer of the 'oral region', 'nose', pharynx and maxillary sinuses. However, the validity of such claims cannot be properly assessed from the available data.

In the two mortality studies conducted on workers at three chromate production plants in the UK, a high incidence of lung cancer deaths was evident among men at two of the plants. Studies at the Eaglescliffe plant provide some evidence of a decline in deaths from lung cancer among workers beginning employment in more recent times, particularly following the introduction of a 'no lime' roasting process; however, the evidence available cannot be considered conclusive. Again, it is not possible to attribute the high lung cancer mortality to particular work activities, or to specific forms or atmospheric levels of chromium. At the Rutherglen plant there was some evidence for an excess in the number of deaths from nasal cancer among the workforce, although in view of the small number of deaths it is not possible to assess the significance of this finding.

Despite various shortcomings in the conduct or reporting of studies, there is evidence of a high rate of lung cancer among workers in the Japanese chromate production industry.

Studies of the production of ferrochromium alloys

In general, the results reported for studies of mortality among ferrochromium workers must be considered inconclusive. There have been suggestions of an excess in lung cancer deaths at a Norwegian plant, and of excesses in mortality due to cancers of the lung, oesophagus and stomach in a Russian study. However, none of these findings are convincing. In addition, such workers appear to have been exposed to substances such as quartz, asbestos and benzo(a)pyrene, which confounds interpretation of the studies.

Welding of stainless steel

Several epidemiology studies have been conducted on stainless steel welders, suggesting excesses in mortality from cancer of various areas of the respiratory tract. However, with respect to effects produced specifically by chromium, these findings are inconclusive, particularly considering the 'mixed exposure' characteristics of the welding fume.

Leather tanning

The vital status of 260 men making chrome-tanned leather in two UK tanneries was ascertained in 1982 and follow-up was 94% complete. Cause-specific mortality within the cohort was compared with national statistics for males. One hundred and forty-four deaths occurred, 126.8 being expected. There was no evidence of any excess mortality from cancers of the lung, gastrointestinal tract, prostate or 'all other sites'.

Applicant's summary and conclusion

Conclusions:

There is no good evidence of adverse health effects in humans arising from occupational exposure to chromium (III) compounds.

Executive summary:

There is good evidence that workers exposed to some forms of chromium in the atmosphere have shown a high incidence of mortality from cancer of the lung or lower respiratory tract (trachea, bronchus, lung). Despite the general absence of detailed analysis of smoking habits, a significant excess in such deaths, attributable to chromium exposure, has been clearly seen among workers in chromate production.

From the few studies available, there is no evidence that occupational exposure to chromium (III) compounds has resulted in cancer in humans.