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Key value for chemical safety assessment

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Assessment of the toxicokinetic behaviour from available information (literature search and existing study) was performed. No experimental toxicokinetic study is available.

DISCUSSION

The chemical composition of both (FBC) Ashes is analogous. But the substance (FBC) Bottom Ash contains higher concentration of Calcium oxide: in (FBC) Fly Ash the total concentration of Calcium oxide is about 19% and in (FBC) Bottom Ash it is about 36%. Size of individual particles of (FBC) Ashes is quite different – structure of (FBC) Fly Ash is rather fine whereas structure of (FBC) Bottom Ash is coarse. In (FBC) Fly Ash more than 90% particles are smaller than 0.074 mm and in (FBC) Bottom Ash more than 94% particles are smaller than 1.00 mm but only about 2.4% of its particles are smaller than 0.08 mm.

 

The influence of different chemical composition and different size of particles of Ashes manifested especially in results of eye irritation/corrossion study. Intensity of eye irritation was higher in (FBC) Bottom Ash: clinical symptoms of irritation were more marked and animals recovered more slowly after application. It corresponded also with literature and database data about Calcium oxide irritation effect.

 

The negative effect of higher concentration of Calcium oxide was expressed also in results of inhalation study: clinical symptoms of irritation of respiratory tract were more marked and animals recovered more slowly after nose exposure to (FBC) Bottom Ash. Observed symptoms during inhalation studies agreed with literature and database data of Calcium oxide. According to database data of Calcium oxide the distribution of aerosols particles in respiratory tract depends on their size: the lung deposition is significantly lower for particles with higher diameters – the size of (FBC) Ashes particles prevents its deposition to the lung. It can be expected that most of Ashes particles were retained in tracheobronchial part of respiratory tract.

 

Changes observed after repeated dose oral exposure were similar in both Ashes but negative influence on reproductive performace of males and females was detected only in (FBC) Fly Ash - the reasons are obscure. No literature or database data about repeated oral exposure to Calcium oxide was found out.  

 

Toxicokinetic data of (FBC) Ashes are quite analogous to data of Ashes (residues) which chemical composition is very similar. In contrast to (FBC) Ashes the substance Ashes (residues) does not contain Calcium oxide. Some differences were detected after eye exposure - Ashes (residues) is not irritant for eye and after inhalation the absorption from respiratory system to blood was confirmed in Ashes (residues). The absorption from respiratory tract can bear on different size of particles.    

 

OVERALL CONCLUSION

Absorption of (FBC) Ashes from the digestive system and their distribution throughout the body of experimental animals to relatively distant compartments was confirmed during oral repeated dose studies. Minerals and metals of (FBC) Ashes are absorbed largely in small intestine. No digestive tract irritation was noted.

 

Absorption to blood circulation after inhalation was not confirmed. The symptoms occured after respiratory exposure to (FBC) Ashes showed evidence rather of local effects and it is not possible to confirm absorption of the test substance from respiration system.

 

Skin and mucosa penetration: according to the studies of skin irritation/corrossion and sensitization the (FBC) Ashes do not penetrate through the skin and they are not skin irritants nor sensitizers. The (FBC) Ashes have certain irritant potential (due to the content of Calcium oxide). After single application to conjunctival sac of eye systemic toxic effects were not detected in Ashes – the substances do not penetrate through the eye. Irritant effect observed in both (FBC) Ashes was caused by Calcium oxide and intensity of irritation depended on concentration of Calcium oxide and on size of particles.

 

According to the experimental data negative influence on reproductive system of rat was described only in (FBC) Fly Ash. No literature data about abbility of Calcium oxide to affect reproduction was found out.

 

No information was found about the bioaccumulation and excretion of (FBC) Ashes.