Sulphur trioxide

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

other: review

Remarks:

IARC

Adequacy of study:

supporting study

Study period:

1997

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The IARC monograph reviews the available epidemiological studies of the carcinogenicity of sulphuric acid

Data source

Reference

Reference Type:

review article or handbook

Title:

Occupational Exposures to Mists and Vapours from Strong Inorganic Acids; and Other Industrial Chemicals

Author:

IARC working group

Year:

1997

Bibliographic source:

IARC Monographs on the evaluation of the carcinogenic risk of chemicals to humans; Vol 54

Materials and methods

Study type:

other: review of available data

Endpoint addressed:

carcinogenicity

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

The IARC monograph reviewed the available epidemiological data relevant to carcinogenicity resulting from occupational exposure to sulphuric acid.

GLP compliance:

no

Remarks:

: not applicable

Test material

Test material information

Constituent 1

Reference substance name:

Sulphuric acid

EC Number:

231-639-5

EC Name:

Sulphuric acid

Cas Number:

7664-93-9

Molecular formula:

H2O4S

IUPAC Name:

sulfuric acid

Method

Exposure assessment:

not specified

Results and discussion

Results:

The IARC Working Groups concluded that there was sufficient evidence that occupational exposure to strong-inorganic-acid mists containing sulphuric acid is carcinogenic.

Any other information on results incl. tables

The IARC Working Group considered the available epidemiological data:

An early study of isopropanol manufacture in the using the strong-acid process demonstrated an excess of nasal sinus cancer.  Studies of one cohort of workers in pickling operations within the steel industry showed excesses of laryngeal and lung cancer after smoking and other potential confounding variables had been controlled for.  A Swedish study of a cohort of workers involved in steel pickling also showed an excess risk for laryngeal cancer. A nested case-control study of workers in a petrochemical plant showed an elevated risk for laryngeal cancer among workers exposed to sulphuric acid.  Of two population-based case-control studies in , one study of laryngeal cancer showed an increased risk for exposure to sulphuric acid, and one of lung cancer suggested an excess risk; the latter also suggested a risk associated with exposure to mixed inorganic acids.  In all these studies, sulphuric acid mists were the most common exposure, and positive exposure-response relationships were seen in two of the studies.  Additional supporting evidence was provided by one cohort study in the soap manufacturing industry in which showed an increased risk for laryngeal cancer.  Studies of three cohorts and one Swedish cohort in the phosphate fertiliser manufacturing industry showed excess lung cancer, but there was potential confounding from exposure to radon decay products in some cohorts.

The following general/mechanistic considerations were made:

Acid mists containing particles with a diameter of up to a few micrometers will be deposited in both the upper and lower airways.  They are irritating to mucous epithelia, they cause dental erosion, and they produce acute effects in the lungs (symptoms and changes in pulmonary function).  Asthmatics appear to be at particular risk for pulmonary effects. Significant increases in the incidences of sister chromatid exchange, micronucleus formation and chromosomal aberrations in peripheral lymphocytes were observed in a single study of workers engaged in the manufacture of sulphuric acid.  The studies reviewed examined the effects of pH values 7 specifically.  In cultured mammalian cells at pH 6.7 or below, cell transformation, gene mutation and chromosomal aberrations were induced.  Mitotic abnormalities were induced in sea urchins and clastogenic effects were seen in plants.  Gene conversion was induced in yeast cells.  No point mutation was observed in fungi, yeast or bacteria.  Acid pH caused depurination of isolated DNA.

Animal carcinogenicity data were not considered by the Working Group.

Applicant's summary and conclusion

Conclusions:

The IARC concluded, based on their review of the available data, that there was sufficient evidence to conclude that occupational exposure to strong inorganic acid mists containing sulphuric acid is carcinogenic. However it is noted that the (negative) animal carcinogenicity studies were not discussed and that there are a number of confounding factors.

Executive summary:

The IARC Working Group reviewed the available human epidemiological studies relevant to the carcinogenicity of sulphuric acid. The animal carcinogenicity data were not considered. It was concluded that the data were sufficient to classify 'occupational exposure to string-inorganic-acid mists contaning sulphuric acid' as carcinogenic to humans (Group 1).