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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
repeated dose toxicity: inhalation
Remarks:
other: evaluation of an authoritative institution
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Evaluation of an authoritative institution. Read-across to kaolin.

Data source

Reference
Reference Type:
other: Evaluation report
Title:
Unnamed
Year:
2007

Materials and methods

Test guideline
Qualifier:
no guideline required
Principles of method if other than guideline:
The Health Council of the Netherlands evaluation by for health based occupational exposure limit
GLP compliance:
no

Test material

Constituent 1
Reference substance name:
Kaolin
IUPAC Name:
Kaolin
Constituent 2
Reference substance name:
Kaolin
EC Number:
310-194-1
EC Name:
Kaolin
Cas Number:
1332-58-7
IUPAC Name:
1332-58-7
Details on test material:
Kaolin (CAS number 1332-58-7; EEC number 310-127-6; RTECS number GF1670500) is a clay that consists primarily of kaolinite (CAS number 1318-74-7; EEC number 215-286-4), a non-fibrous aluminium silicate with the molecular formula Al2O3⋅2SiO2⋅2H2O. Kaolin is a fine white to light-yellow powder with an earthy taste.3 It usually contains small amounts of other minerals such as quartz, mica and TiO2. The amounts differ depending on the geographic location at which the kaolin is extracted.

Test animals

Species:
other: several

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
other: Evaluation of an authoritative institution
Details on inhalation exposure:
Review

Results and discussion

Results of examinations

Details on results:
The occupational exposure to kaolin has adverse health effects involving the lungs and with pneumoconiosis as the clinical finding.
The occupational exposure to 2.1 mg/m3 respirable kaolin dust constitutes an substantial risk for the development of pneumoconiosis ILO category 1. However, no studies are available from which to establish a NOAEL or LOAEL for kaolin dust.

Effect levels

Dose descriptor:
NOAEC
Remarks on result:
not determinable
Remarks:
no NOAEC identified

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Many reports of well-studied cases and a number of cross-sectional studies have shown that long-term exposure to kaolin may lead to pneumoconiosis, which has been named kaolinosis. Pneumoconiosis is diagnosed by chest X-ray, and is categorized as simple pneumoconiosis (category 1-3) or complicated pneumoconiosis (category A-C). Clinical symptoms and effects on pulmonary function are mainly observed in the complicated form. Although the mildest form of pneumoconiosis ILO category 1 is not yet associated with a decrease of pulmonary function, the pneumoconiosis category 1 can be considered as an undesired health effect, in

agreement with the European Committee’s report on miner’s pneumoconiosis. Studies with exposure data or dose-effect relationships are scarce. The available animal data are not suitable for the derivation of a health-based recommended

occupational exposure limit.

Adequate studies on the carcinogenicity or reproduction toxicity of kaolin are not available.

There is one study with human data in which a dose-response relationship was reported for respirable kaolin dust. According to this study, the average nonsmoking worker reaches pneumoconiosis ILO category 1 at the age of 60 after 40 years of occupational exposure to 2.1 mg/m3 respirable kaolin dust. From the data as presented in this publication, the committee can not establish a NOAEL or LOAEL. The publication does not contain information on the quartz content of the respirable dust exposures, the presence of which in kaolin can make it difficult to distinguish kaolinosis from silicosis (pneumoconiosis caused by quartz).

Applicant's summary and conclusion

Conclusions:
The exposure to kaolin has adverse effects involving the lungs and with pneumoconioisis as the clinical finding. However, no studies are available from which to establish a NOAEL or LOAEL for kaolin dust.
Executive summary:

The available data on repeated dose toxicity caused by kaolin was evaluated by DECOS (2007).The available animal data are not suitable for the derivation of a health-based recommended occupational exposure limit.

There is one study with human data in which a dose-response relationship was reported for respirable kaolin dust.2 According to this study, the average nonsmoking worker reaches pneumoconiosis ILO category 1 at the age of 60 after 40 years of occupational exposure to 2.1 mg/m3 respirable kaolin dust. From the data as presented in this publication, the committee can not establish a NOAEL or LOAEL. The publication does not contain information on the quartz content of the respirable dust exposures, the presence of which in kaolin can make it difficult to distinguish kaolinosis from silicosis (pneumoconiosis caused by quartz).

The occupational exposure to kaolin has adverse health effects involving the lungs and with pneumoconiosis as the clinical finding.

However, no studies are available from which to establish a NOAEL or LOAEL for kaolin dust.