Hazards of Worker Exposure to Paints

There are a vast number of chemicals that can be contained in paints—solvents, pigments, metals, resins, plasticizers—anyone or all of these may cause adverse health effects especially to workers who are exposed to them on a daily basis.
The best way to characterize the hazards to workers who are regularly exposed to paints is to identify the different type of paints—their ingredients—and their hazards.
The various types of paints include:

1. Water based paints.
2. Oil/solvent based paints.
3. Resin-type paints.
4. Dry powder coating paints.

The following is a breakdown of the ingredients of each type and the nature of the ingredients that may pose potential health problems to the worker/applicator.

1. Water Based Paints: These paints were developed over the last two (2) decades to reduce the solvent emissions from paint application. Generally they are latex paints (either natural rubber latex or synthetic latex) and are water soluble. They may have some low level of solvents (also called Volatile Organic Compounds – VOCs) that are water soluble such as isopropyl alcohol (isopropanol), and methyl alcohol (methanol) and tend generally not to be hazardous to the worker. They are still recommended to be used in a paint booth or other area with adequate ventilation. In some cases, the pigment/colorant may be of concern such as carbon black (a carcinogen).
2. Oil/Solvent Based Paints. Formerly the predominant form of paint in commercial/industrial applications but not currently used as extensively as in the past due to the solvent content. There can be a wide variety of solvents contained in them depending upon the manner and speed of drying required. The faster the drying time, the more likely the evaporating solvents could pose a problem to the worker. They can pose acute (short-term) or chronic (long-term) health effects. Because of the great variety of solvents used, it is important to view the paint ingredients from the Safety Data Sheet (SDS) for type and amount of each solvent. Oil based paints may also contain pigments that may be of concern.
3. There are two groups of emissions from such a paint operation. 1. the solvents and the 2. particulates. The pigments are the particulates, either solid or liquid, that may be of concern in worker exposure. The pigments of concern are such things as cadmium, cobalt, lead, manganese, carbon black—all of which have worker exposure limits. Again it is important to consult the SDS, and perform sampling/testing of the paint spray operator for both the solvents and the particulates. Such paint spraying of oil/solvent based paints should always be done in a well ventilated, paint spray booth.
4. Resin Type Paints. These paints were also developed as a means of reducing solvent/VOCs emission that could expose workers and emit pollutants to the atmosphere. Such resin paints have two components—most commonly referred to as the “A” and “B” components. In most commercial uses, the A and B components are compiled at the spray nozzle and they rapidly form a polymic coating that coats the surface of the item that is painted. The A component is generally the colorant and the chemical coating and the B component is what caused the chemical reaction to polymize the paint. The A component often has some low level of solvent to keep it liquid and the B component is the curing agent. Although there is seldom any solvent of concern, the polymer is often an isocyanate which can result in a strong asthmatic type respiratory reaction in a person sensitive to the isocyanate. Typical isocyanates are TDI, MDI, and poly-isocyanates. Once an individual is sensitized, it is likely they cannot work in any proximity to the isocyanate thereafter. All of these resin based paints should be applied in a well ventilated spray booth and the worker be monitored for the particular isocyanate identified on the SDS.
5. Dry Powder Coating Paints. This form of paint contains no liquid component. It is almost always applied to metal parts since they can hold an electric charge that aids in the dry powder coating will adhere until the part goes through a temperature controlled oven that “melts” the coating to the part’s surface. Generally, these coatings contain a dry plastic powder that melts to the surface when passed through the oven. In general, the only worker/applicator exposure is to the dry powder and most often just a nuisance particulate. The only exception is that some of the dry components can be hazardous such as carbon black. Remember that there are exposure limits to even nuisance dusts and there is generally a good amount of dusty overspray. As with other types of paints/surface coatings, this work should be performed in a spray booth. Monitoring of the worker’s exposure is advisable if the SDS identifies components of concern including the particulates.

The final element to insuring a healthy environment is that all forms of surface coating applications be done in a ventilated paint booth. Also, the worker should be monitored if there is concern about the paint components AND if the worker wears a respirator. OSHA requires that a worker be monitored to determine if the respirator is necessary and the respirator in use is the proper one (29CFR1910.134).