Chromium trioxide

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1946-1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Published epidemiology study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Materials and methods

Study type:

cohort study (retrospective)

Endpoint addressed:

carcinogenicity

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Extension to an earlier cohort study investigating the incidence of lung cancer in electroplating workers occupationally exposed to chromic acid mist (aqueous chromium trioxide)

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Chromic acid

EC Number:

231-801-5

EC Name:

Chromic acid

Cas Number:

7738-94-5

Molecular formula:

CrH2O4

IUPAC Name:

dihydroxy(dioxo)chromium

Constituent 2

Reference substance name:

chromium (VI) trioxide

IUPAC Name:

chromium (VI) trioxide

Constituent 3

Reference substance name:

Chromium trioxide

EC Number:

215-607-8

EC Name:

Chromium trioxide

Cas Number:

1333-82-0

Molecular formula:

CrO3

IUPAC Name:

trioxochromium

Details on test material:

Workers had previously been occuaptionally exposed to chromic acid mists (aqueous chromium trioxide)

Method

Type of population:

occupational

Details on study design:

The mortality experience of a cohort of 1762 chrome workers (812 men, 950 women) from a large electroplating and light engineering plant in the Midlands, United Kingdom, was investigated for the period 1946-95. All subjects were first employed in chrome work at the plant during the period 1946-75, and had at least six months employment in jobs associated with exposure to chromic acid mist (hexavalent chromium).

Exposure assessment:

estimated

Results and discussion

Results:

Based on mortalities for the general population of England and Wales, male workers with some period of chrome bath work had higher lung cancer mortalities (observed deaths 40, expected deaths 25.41, standardised mortality ratio (SMR) 157, 95% confidence interval (95% CI) 113 to 214, (p<0.01) than did other male chrome workers (observed 9, expected 13.70, SMR 66, 95% CI 30 to 125). Similar findings were shown for female workers (chrome bath workers: observed 15, expected 8.57, SMR 175, 95% CI 98 to 289, p = 0.06; other chrome workers: observed 1, expected 4.37, SMR 23, 95% CI 1 to 127). Poisson regression was used to investigate risks of lung cancer relative to four categories of cumulative duration of chromebath work and four categories of cumulative duration of other chrome work (none, < 1 y, 1-4 y, > or = 5 y). After adjusting for sex, age, calendar period, year of starting chrome work, period from first chrome work, and employment status (still employed v left employment), there was a significant positive trend (p<0.05) between duration of chrome bath work and risks of mortality for lung cancer. Relative to a risk of unity for those chrome workers without any period of chrome bath work, risks were 2.83 (95% CI 1.47 to 5.45), 1.61 (95% CI 0.75 to 3.44), and 4.25 (95% CI 1.83 to 9.87) for the second, third, and fourth exposure categories, respectively. Duration of other chrome work was not a useful predictor of risks of lung cancer. Similar findings for both variables were obtained when adjustment was made for sex and age only. Similar findings for both variables were obtained relative to risk of chrome nasal ulceration.

Any other information on results incl. tables

The findings of this study are consistent with the hypothesis that chromium trioxide is a human lung carcinogen.

Applicant's summary and conclusion

Conclusions:

The results of this study confirm the earlier findings that exposure to Cr (VI) in chrome plating work causes a significant increase in the risk of death from lung cancer.

Executive summary:

The mortality experience of a cohort of 1762 chrome workers (812 men, 950 women) from a large electroplating and light engineering plant in the Midlands, United Kingdom, was investigated for the period 1946–95. All subjects were first employed in chrome work at the plant during the period 1946–75, and had at least six months employment in jobs associated with exposure to chromic acid mist (hexavalent chromium).

There were 752 deaths. The mortality in the cohort was compared with that which might be expected based on mortalities for the general population of England and Wales, taking into account age, sex and calendar year. For those workers with no exposure to chrome bath work, no excess in lung cancer mortality was found (observed 9, SMR 66) whereas a higher SMR was calculated from the statistics for men exposed to chrome bath work (for any period) (observed 40, expected 25.4, SMR 157, 95% CI 113-214, p0.01). A statistically significant increased lung cancer SMR was calculated for all male chrome workers 10-19 years after first working with Cr(VI) (observed 18, expected 8.85, SMR 203 95% CI 121-321, p<0.01) but other periods of follow-up did not show a statistically significant excess. Poisson regression was used to investigate risk of death from lung cancer relative to 4 categories of cumulative exposure of chrome bath work or other chrome work (none, 1 year, 1-4 years, > or = 5 years). A significant positive statistical trend was observed for lung cancer mortality in men and cumulative duration of chrome bath work (p0.01). In the case of men employed for 5 years or more in chrome bath work, the SMR for lung cancer mortality was 375 (10 observed, 2.7 expected, 95% CI 180-689, p<0.001). A raised SMR was also found for women workers with any chrome bath work (observed 15, expected 8.6, SMR 175, 95% CI 98-289, p=0.06). This study confirms the earlier findings that exposure to Cr (VI) in chrome plating work causes a significant increase in the risk of death from lung cancer. It remains impossible to establish a clear dose-response relationship for this excess risk of lung cancer.