Registration Dossier

Administrative data

Endpoint:
health surveillance data
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: study well documented, meets general scietific principles, acceptable for accessment

Data source

Reference
Reference Type:
publication
Title:
Effects of chronic amorphous silica exposure on sequential pulmonary function.
Author:
Wilson, R. K., P. M. Stevens, et al.
Year:
1979
Bibliographic source:
J Occup Med.21(6): 399-402.

Materials and methods

Study type:
human medical data
Endpoint addressed:
repeated dose toxicity: inhalation
Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Study contained evaluation of serial spirograms, respiratory questionnaires and chest x-ray pictures of 165 workers exposed to precipitated silica for a mean of 8.6 years. Cumulative exposure indexes taking into account the quantity and duration of exposure were created for each individual.

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Type of population:
occupational
Ethical approval:
no
Details on study design:
The medical records of 165 precipitated amorphous silica (PAS) exposed workers in two industrial facilities were evaluated with regard to annual spirometry, chest roentronogram and most recent respiratory questionnaire. Workers were exposed for at least one year to PAS.Demographic data, smoking histories and positive responses to respiratory health questions were obtained from their medical chart. Relationship of symptoms and PAS exposure and symptoms and smoking was evaluated. Chest X-rays pictures were evaluated for pneumoconiosis. Cumulative dust exposure was calculated for each worker by summing monthly dust exposure. Dust exposure estimation was based on measured data. No external control group was included in the study. Statistical analysis was performed: student's t-test, Fisher exact test, linear and multiple regression and analysis of variance.

Results and discussion

Results:
No correlation between cumulative exposure and respiratory function measures were seen. Symptoms did not increase with increasing cumulative exposure. No cases of pneumoconiosis were detected. Cough, dyspnea and respiratory function correlated with tobacco smoking.

Applicant's summary and conclusion

Conclusions:
No relationship between amorphous silica exposure and respiratory symptoms or decline in respiratory function was seen. No cases of pneumoconiosis were observed.
Executive summary:

Wilson (1979) reviewed serial spirograms, respiratory questionnaires and chest x-ray pictures of 165 workers exposed to precipitated silica for a mean of 8.6 years. Cumulative exposure indexes taking into account the quantity and duration of exposure were created for each individual. No correlation between the cumulative exposure and respiratory function measures were seen. Neither did the symptoms increase with increasing cumulative exposure. No cases of pneumoconiosis were detected. Cough, dyspnea and respiratory function correlated with tobacco smoking. No external control group were included in the study.