Carbon black and titanium dioxide play a variety of important roles in the products of today’s industries. Typically formed from the incomplete combustion of liquid or gaseous hydrocarbons, carbon black has traditionally been used as a reinforcing agent in tires. However, the tinting strength and full hiding ability of this fine powder have allowed it to function as a pigment in various paints and inks as well.
Contrastingly, titanium dioxide is a naturally occurring mineral that can be found in a variety of crystalline structures. When transformed into a powder, it acts as a strong white pigment with high opacity. These characteristics have made it an ideal ingredient in a variety of products ranging from make-up powders, sunscreens, and toothpaste to floor coverings, roofing materials, and coatings.
Health Risks Are High
Despite these advantages, the side effects that come with overexposure to either of these chemicals can be potentially fatal. Particles of both substances can irritate a person’s body in a variety of different ways. Upon entering the eye, they cause redness, eye-watering, and uncomfortable soreness. Skin contact with this chemical can cause mild irritation, soiling, and skin dryness. The best course of action to take in these cases of exposure is to wash the area thoroughly. On the other hand, the most dangerous route of exposure is inhalation. Carbon black and titanium dioxide irritate the respiratory tract, causing a person to cough or wheeze. They can also aggravate respiratory disorders, such as asthma, so it is important to enforce proper ventilation when handling this substance to ensure the amount of dust stays below the occupational exposure limit. Most severely, overexposure can lead to cancer in the lungs, as recognized by the International Agency for Research on Cancer (IARC).
The International Agency for Research on Cancer (IARC) is an agency under the World Health Organization that works to evaluate the evidence that a specific chemical agent, compound, or mixture can elevate the risk of cancer in humans. Based on the available research, substances are classified into one of four categories: 1, 2A, 2B, and 3. Carbon black and titanium dioxide are both classified as Group 2B carcinogens, meaning there is limited scientific evidence supporting an increased risk of cancer in humans, but sufficient evidence supporting an increased risk in animals. The IARC also evaluates biological mechanisms before deciding on a final risk level when analyzing animal data for human risk.
Safe in Paint
Despite the carcinogenic ratings of these products, they are not carcinogenic when used in our paint due to encapsulation or preserving and isolating their chemical/physical properties. For these particles to potentially cause cancer, they must be inhaled. Due to its very stable structure, carbon black does not dissolve in water and tends not to dissolve in solvents. Titanium dioxide is not usually soluble in common polar/nonpolar solvents since it is not a salt. This means it would be very difficult for these particles to be transferred into the air in the form of a vapor. Additionally, once our paint is applied to a surface and has dried, the particles are in a solid form and are no longer mobile assuming the dried layer is not sanded.
While the carbon black particles in our paint are encapsulated, formulas containing greater than or equal to 0.1% carbon black by weight are still flagged and marked as a 2B carcinogen. In the case that a company wants to purchase a black paint that will not have this rating, there are alternate formulations that can be constructed to achieve the same visual results but with less carbon black.
Meeting Our Customer’s Safety Protocol
To satisfy a customer’s request, we altered a UV curable formula by taking out as much carbon black UV tint paste as needed to make its percent weight less than 0.1%. This work was to minimize employee risk, an important consideration for this customer, rather than an attempt to avoid the 2B rating on an SDS. After observing that the paint was not dark enough to satisfy the customer, we decided to investigate other tinting methods. Black “tar” was found to be incompatible, while organic black dyes were either incompatible or not UV stable. Finally, we formulated an in-house black tint paste by milling black iron oxide pigment into a UV monomer. Seeing that this showed some potential, we worked with our carbon black tint paste supplier to manufacture a large-scale black iron oxide tint paste. Because iron oxide has no IARC carcinogen rating, we were able to use this tint paste along with the limited amount of the carbon black tint paste to create a paint that was not labeled as a carcinogen-containing product, hence satisfying our customer’s desire to minimize risk to their employees.
Marcus Paint Company maintains a very proactive approach to assisting our customer’s needs, whether through consultative & technical online services or unique formulation alternatives. To view all of our case studies, press here.