Carbon Black: A Black Powder That Causes Many IAQ Problems 

What carbon black is
Sources of carbon black
Health problems associated with carbon black
Decreasing exposure to carbon black

What Carbon Black Is

Carbon black is a black, odorless solid in the form of powder, pellets or paste. It is used in making tire treads, in abrasion resistant rubber products, and as a pigment for paints and inks.

Sources of Carbon Black

• It is mainly used as a reinforcing agent in rubber products such as tires, tubes, conveyer belts, cables and other mechanical rubber goods.

• In an office environment it is seen in photocopier toner.

• It is used as a black pigment in printing, lithographic, letterpress, carbon paper and typewriter ribbon inks, paints, coatings, lacquers, plastics, fibers, ceramics, enamels, paper, and record discs.

• In leather finishes.

• In the manufacturing of dry-cell batteries.

• As high temperature insulating material.

Health Problems Associated With Carbon Black

Health problems caused by carbon black can either be acute, which occur immediately or within a few days of exposure, or they can be chronic, which are long-term health effects that might not show up for many years. Carbon black does not appear to cause any major harmful effects after a single short-term exposure, except for health effects that are usually seen with high concentrations of any fine dust such as coughing and mild, temporary irritation. However, carbon black can possibly cause serious respiratory effects following long- term inhalation.

Is a person exposed to just carbon black or is it a variety of chemicals? There are usually other chemicals that get stuck onto the carbon black surface. These include various polycyclic aromatic hydrocarbon (PAH) compounds that can cause cancer. The presence of these PAH compounds can greatly increase the health hazards associated with carbon black.

Exposure to carbon black can result in:

• Irritation of the eyes with tearing, blinking, and mild pain from the fine dust.

• Nose and throat irritation resulting in throat dryness, coughing and wheezing.

• Irritation of the skin: Though carbon black cannot be absorbed into the skin, fine particles of it can become trapped in hair follicles causing discoloration (carbon black "tattoos") and follicular blackheads.

• Irritation of the lungs: Repeated exposures may cause bronchitis to develop with cough and phlegm production.

• Carbon black is listed by the International Agency for Research on Cancer (IARC) as a Group 2B carcinogen, possibly carcinogenic to humans.

• Carbon black may be contaminated with pollutants that are known carcinogens such as PAHs (associated with lymphatic cancer) and benzo (a) pyrene.

• Irreversible lung problems: Carbon black dust is extremely fine and light and can be breathed deeply into the lungs, where it can accumulate. High concentrations of dust (10 to 100 mg/m³) can overwhelm the ability of the lungs to clear themselves which results in obstruction of the lungs as well as impaired lung function. A number of studies have shown x-ray changes, reduced lung function, evidence of fibrosis (scarring of the lungs) in the area surrounding carbon black deposits in the lungs, emphysema and/or chronic bronchitis in some carbon black workers.

Decreasing Exposure to Carbon Black

Minimize the amount of time that one is around carbon black. Generally, there will not be problems with the levels of carbon black seen in an office environment.