Chromium trichloride

Health surveillance data

Administrative data

Endpoint:

health surveillance data

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented study investigating exposure to chromium (III) in ferro-chrome manufacturing setup and checking for urinary data to assess renal impairment. Cohort of sufficient size (199 volunteers participating in study)

Data source

Reference

Reference Type:

publication

Title:

EFFECTS DERIVED FROM LONG-TERM LOW-LEVEL CHROMIUM EXPOSURE IN FERRO-ALLOY METALLURGY. STUDY OF ABSORPTION AND RENAL FUNCTION IN WORKERS

Author:

V. FOA, L. RIBOLDI, M. PATRONI, C. ZOCCHETTI, C. SBRANA and A. MUTTI

Bibliographic source:

The Science of the Total Environment, 71 (1988) 389-400

Materials and methods

Study type:

biological exposure monitoring

Endpoint addressed:

other: inhalation absorption

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

see details on study design below

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

chromium(III) oxide

IUPAC Name:

chromium(III) oxide

Constituent 2

Reference substance name:

Chromium (III) oxide

EC Number:

215-160-9

EC Name:

Chromium (III) oxide

Cas Number:

1308-38-9

Test material form:

not specified

Details on test material:

Exposure to chromium(III) oxide in ferro-chrome production was investigated

Method

Type of population:

occupational

Ethical approval:

not specified

Details on study design:

To investigate toxicity of trivalent chromium, a study on the working population of a ferro-chromium foundry was performed, which included assessment of the level and type of exposure, the degree of absorption of the metal, short and medium term effects (skin, gastro-intestinal, kidney and lung damage) and long term effects (study of the causes of death). The paper reports the preliminary results of exposure and absorption levels, and effects on kidney function.
The study was carried out at a foundry that has been producing ferro-chromium since 1972, by means of reduction of chromite with coke, with bauxite and quarzite as fusion agents in triphase electric submerged arc furnaces. A total of 236 subjects were employed at the plant, all of whom were males: 142 were employed on production, 33 were office Staff, and 61 were employed by sub-contractors on production.
29 office staff members (clerks), 124 workmen and 46 sub-contractors participated in the study. Their average age was 43 ±7, 41 ±9 and 37 ±13 years respectively and their length of exposure in plant was 10 ±5, 12 ±8 and 2 ±2 years respectively. The population was on the whole homogeneous both as regards age and length of exposure, except in the subcontractor employees for which there was a more rapid turnover. A detailed analysis was made of the production cycle, with a systematic study of the tasks. For the study of environmental exposure, atmospheric concentrations of total dust, total chromium and hexavalent chromium were measured. Total chromium was determined by means of alkaline fusion in platinum crucibles with sodium hydroxide and lead nitrate and, after cooling, solubilization in distilled water acidified with hydrochloric acid. Analysis was performed using the atomic absorption spectrophotometric technique.

Results and discussion

Any other information on results incl. tables

Airboren concentrations of total dust, total chromium and hexavalent chromium in different workstations

sample location	total dust [mg/m3]	total chromium [mg/m3]	% chromium in dust	chromium(VI) in mg/m3]
conveyor belts and scales room	6.85	0.158	2.3	<0.001
Electrode lining	6.66	0.109	1.6	<0.001
furnace load	2.12	0.024	1.1	<0.001
casting	2.17	0.021	0.9	<0.001
crushing	3.28	0.117	3.8	<0.001
selection	1.66	0.020	2.0	<0.001

The values were always relatively low and in any case well below the limits currently considered as acceptable for exposure to chromium. The highest values were found in the conveyor belt/scales area (arrival area of raw material for loading in furnaces from conveyor belts); in the electrode lining replacement (area located above the furnaces) and in the alloy crushing area. The levels of hexavalent chromium were below the sensitivity of the analytical method (0.001 mg/m³) and, therefore, negligible.

Dispersion of other pollutants (asbestos fibres, estimated with AIA standardized method and sulphur dioxide and carbon monoxide, estimated with gas detector tube) which were measured in order to make a more complete assessment of the exposure hazard, was negligible (asbestos <= 0.01 ff/cm³; SO2 and CO traces).

In the areas already mentioned (conveyor belt/scales; electrode lining replacement), total dust and respirable fraction exceeded the TWA, taking into account the silica content of the dusts (usually ~1% but never > 2%). Like the environmental pollution levels, the urinary chromium levels were also rather low. Only in 4 subjects (3 maintenance men and one furnace loading operator) were observed values > 5 µg/g creatinine (all in the end-of-shift sample), which is currently considered as a biological exposure limit.

In all groups, the mean end-of-day value was higher than the morning value, suggesting a process of chromium absorption related to working activity; absorption was, however, very limited, never exceeding a value of 1.7 µg/g creatinine.

The end-of-shift values were similar to those of the end-of-day levels. It can, therefore, be presumed that renal clearance of the metal is low, thus indicating low accumulation and, therefore, low exposure over time. Age and length of exposure did not seem to have any influence on the results since they were homogeneous in the various groups.

Mean values of urinary chromium (µg/g creatinin) in workers at different times

worker category	beginning of 1st working day	end of 1st working day	end of last day of shift
clerks	0.60 ±0.59	0.69 ±0.40	0.58 ±0.55
workmen	0.94 ±0.74	1.21 ±1.01	1.25 ±1.30
sub-contractors	0.77 ±0.46	0.96 ±0.71	1.05 ±0.71

Job analysis confirms the following trend: absorption occurs in all groups except ferro-chromium sorters. The extent of this phenomenon, although very limited, is greater in the raw material input operators, scales, furnace assistants and crushing operators, dust elimination operators and maintenance men employed on sub-contracted building work. This finding agrees with the higher levels of pollution found in the scales area, in the area above the furnaces and in the ferro-chromium crushing area.

The mean values of the indicators of possible renal impairment were within normal limits. Differences between groups were observed for RBP (which was relatively higher in the sub-contractor employees) and BB50 (which was slightly higher in the office workers); the percentage of subjects with values > 95 ° percentile was similar to that observed in the non-occupationally exposed population. These subjects (13 in total) did not show high levels of urinary chromium and only 3 of them were employed on jobs where a higher degree of absorption was observed (crushing, dust elimination and building maintenance work).

Job analysis confirmed the overall similarity of the mean urinary albumin values with higher RBP values among scales, crushing, routine maintenance and dust elimination operators and among building and machine maintenance workers employed by sub-contractors. This finding, compared with the urinary chromium results, only partially agrees with previous observations: no particularly higher chromium absorption was observed among routine maintenance workers and sub-contractor machine maintenance workers. Multiple regression analysis between urinary chromium, age, length of exposure and renal damage tests did not reveal a significant correlation between these variables.

Applicant's summary and conclusion

Conclusions:

No renal impairment of workers exposed to chromium(III) oxide in a ferro-chrome manufacturing plant could be seen. Occupational exposure to workers was low (<0.16 mg Cr(III)/m3) and hexavalent chromium could not be detected.

Executive summary:

The data permit some preliminary observations to be made. In the first place, it would appear that, under the manufacturing conditions present in this factory, ferro-chromium metallurgy should not involve heavy exposure to respirable chromium, and even less to hexavalent chromium. The concentrations may have been higher in the past, but at present the values are well below those observed by Axelson (G. Axelson, R. Rylander, A. Schmidt, Mortality and incidence of tumours among ferro-chromium workers, Br. J. Ind. Med., 37 (1980) 121-127.) in the late 70's in a similar type of plant in Sweden, and by Langard in Norway in the same period (S. Langard, in: Waldron H.A. (Ed.), Metals in the Environment, Chromium, Academic Press, London, 1980, p. 111). Exposure appears to be mainly, if not exclusively, due to trivalent chromium, i.e. in the less absorbable form.

The levels of absorption were very low, especially if compared with those observed in chromium electro-plating, special steel welding and chromate production (T. Norseth, The carcinogeneticy of chromium, Environ. Health Persp., 40 (1981) p. 121) where exposure is to hexavalent chromium. The values found in this study even appear not to be very different from those observed by other authors in non-occupationally exposed subjects.

Nevertheless, the absorption levels varied according to the job, thus agreeing with the environmental pollution data. If a measurable exposure to hexavalent chromium can be excluded on the basis of these environmental data (further checks are under way), it must be assumed that total urinary chromium is derived exclusively from absorption of chromium originally in the trivalent state.

It would, therefore, appear that this form of chromium, too, can be absorbed, as reported by other authors. The low levels of urinary chromium observed at the end of the shift indicate a low renal clearance of chromium and, therefore, little or practically no accumulation, in spite of long-term exposure. The observations are confirmed by the fact that no early functional renal damage was found, in spite of the reliability and sensitivity of the indicators used. However, the tubular epithelium is capable of repairing any damage suffered, by means of regeneration mechanisms, thus making it difficult to detect effects of low-level chronic exposure.

We, therefore, cannot confirm whether the absence of renal damage was due to non-toxicity to trivalent chromium, or to the low levels of exposure and absorption observed, or to the more rapid regenerative power of renal epithelium, which can repair damage before it becomes evident, at least with the current methods of investigation.

However, the fact remains that in the working conditions under study, not even initial renal impairment could be observed. The study of other possible health effects (skin effects or effects of respiratory and digestive systems) and of a possible excess of cancer would furnish further data which may help to throw light on these points.