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Diss Factsheets

Toxicological information

Respiratory sensitisation

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Administrative data

respiratory sensitisation
other: Ex vivo study on guinea pig trachea, relating to respiratory sensitisation and irritation.
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented publication which meets basic scientific principles.
Reason / purpose for cross-reference:
reference to other study

Data source

Reference Type:
Pharmacologic effects of cocoa and rye flour extracts on isolated guinea pig trachea
Schachter E.N., Zuskin E., Rienzi N. and Goswami S.
Bibliographic source:
Journal of Toxicology and Environmental Health Part A, 56, 137-148

Materials and methods

Test guideline
no guideline available
Principles of method if other than guideline:
Ex vivo study on isolated guinea pig trachea to evaluate contraction in response to treatment with a cocoa extract at up to 50 μl/ml.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
Cocoa ext.
Cocoa ext.
Constituent 2
Reference substance name:
Cocoa, ext.
EC Number:
EC Name:
Cocoa, ext.
Cas Number:
Details on test material:
- Name of test material (as cited in study report): cocoa extract
- Substance type: no data
- Physical state: in aqueous solution
- Analytical purity: no data
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: the 10% extract contained 45 μg/ml protein
- Isomers composition: no data
- Purity test date: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: -20 °C
- Other: dust extracts were prepared from cocoa collected from machines in a Croatian confectionery plant. In preparing the extract, the allergen raw material was defatted with diethyl ether, and then stirred in phosphate-buffered saline for 72 hours at 4 °C. The extract was then centrifuged and purified.

Results and discussion

Applicant's summary and conclusion

A 10% cocoa extract significantly induced dose-related contraction in isolated guinea pig tracheal segments. Blocking agents, particularly atropine, significantly inhibited this contraction. The results suggest cocoa extract can induce airway contraction via non-immunological mechanisms.
Executive summary:

An ex vivo study has been conducted on segments from the tracheas of non-sensitised guinea pigs in order to elucidate the mechanisms by which cocoa extract can induce airway constriction.


Tracheas from 18 males were removed and each cut into four rings. These were suspended in a 20 ml organ chamber. One ring from each guinea pig was exposed to increasing concentrations of 10, 30, 100, 300 and 1000μl [0.5, 1.5, 5, 15 and 50μl/ml] of a 10% cocoa extract. The other three rings were pre-treated for 30 minutes with one of nine blocking agents, and were then exposed to the cocoa extract at the same five concentrations.


Cocoa extract caused significant, dose-related contraction, with an Emax(observed maximal muscle tension as a percentage of the maximal contraction induced by 0.1 mmol/L of carbachol) of 125.3±7.9%. The average EC50 (the concentration eliciting half of the cocoa extract’s maximal response) was 30.09±6.7μl [1.5± 0.3 μl/ml]. Contraction was significantly inhibited by each blocking agent.


The results were said to suggest “a complex interaction between” this airway irritant and “guinea pig tracheal tissue”, and that “clinical effects of cocoa … in workers are probably related to non-immunologic (non-IgE) mechanisms similar to those seen with other organic dusts extracts”. In particular, cholinergic mediators were seen to play a key role in airway constriction, as atropine (which is anticholinergic) almost completely blocked constriction.