Product Safety of Carbon Blacks

Experience with humans

Findings collected over the past decades in the context of manufacturing and processing of Carbon Black have shown no significant detrimental effects on humans when used as directed.

Acute toxicity

Acute oral toxicity LD50, rat, is above 8,000 mg/kg. Amounts below 5,000 mg/kg are considered nontoxic. Applying carbon black on the skin and eye of a rabbit did not indicate any sensitivity.

Chronic toxicity

The results of both long-term inhalation studies and research on intratracheal instillation published in the early nineties show that chronic inflammations, lung fibrosis and tumor formation are possible under so-called “lung overload” conditions. Only rats showed positive findings in these trials, while no tumors were detected in mice or hamsters. The role played by the type of animal species, the effect of fine powder and the mechanisms of tumor formation are unknown at this time.

The International Agency for Research on Cancer (IARC) used these trials to establish a new classification for industrial carbon blacks. Though the evaluation of epidemiological data (inadequate evidence) was maintained, the more recent findings from rat trials led to a reclassification from Category 3 to Category 2B (possible human carcinogen). This new classification means that carbon black now figures in the Danish Cancer List. Based on the Workplace Hazardous Materials Identification System (WHMIS), carbon black counts as a D2A Substance (poisonous and infectious material) as per the Canadian Environmental Protection Act (CEPA). In Germany, the MAK Commission listed carbon black among Category 3B substances (possible carcinogens).

Current European Union (EU) directives and American regulations (OSHA) on chemical substances do not list carbon blacks as mutagens, teratogens or carcinogens.

Ecotoxicology

Carbon Black is non water-soluble, reducing the risk of bioavailability and the related systemic toxicity for aquatic organisms. Examination of carbon black filter residue, based on an initial concentration of 1000 mg/l showed no observable effect on fish, daphnia and algae. Carbon black is an inert, inorganic substance with C as a structural formula and is not metabolized by microorganisms. Carbon Black is listed as a “non-hazardous to water” substance (ID# 1742) in the official “substances hazardous to water” catalog.

Advisory on safe handling and usage

Carbon Black is non-explosive under practical usage conditions. However, if significant ignition forces are present, e.g. in the form of a welding tool, Carbon Black/air mixtures may cause an explosion. For this reason, in case of repairs on production facilities, e.g. in the course of welding activities, the area in which repairs or maintenance is undertaken must be kept free of Carbon Black.

Carbon monoxide may be present in closed containers, e.g. silos, or within insufficiently ventilated storage facilities, e.g. warehouses. For this reason, sources of fire are to be avoided and personnel should wear protective respiratory gear that is independent of ambient air.

Carbon Black must be stored in a dry location. If during processing the amount of fine powder (absorbable by alveoli) exceeds 1.5 mg/m³ and the concentration of inhalable dust (general dust) exceeds 4.0 mg/m³ , the facility must be equipped with an air suction system or personnel must wear a Particle P1 dust mask. In the US, the limit for general dust (TWA) is 3.5 mg/m³. Spilled material may be collected mechanically under avoidance of a dust build-up, filled into appropriate containers, stored or burned in adequate firing facilities.

Please see the relevant safety data sheets for further details on measures for safe handling of carbon blacks.