Many solvents pose serious health and safety hazards, and the government is increasingly regulating worker exposure and overall usage. Epoxy users commonly use solvents to dissolve epoxy from tools and to degrease surfaces before bonding. Solvents’ ability to dissolve and degrease is part of why they are hazardous to your health. They leach oils from the skin and break down protective fatty layers. This makes skin more susceptible to dermatitis. While dermatitis is the most common skin problem solvents cause, it doesn’t stop there.
Once solvents have penetrated the protective skin layers, they may quickly find their way into the blood stream. You can absorb toxic amounts in this way. If you use solvent to clean epoxy from your skin, your skin can absorb both the solvent and the dissolved epoxy. This will intensify epoxy exposure.
Almost all solvents are toxic if you swallow, absorb or inhale enough. Solvents can irritate your respiratory system, eyes, and skin. Some solvents may damage your heart, liver, and other vital organs. Several solvents have been linked to cancer.
Repeatedly inhaling low to moderate levels of solvents can irritate the respiratory tract. Because of their drying effect, solvents can also interfere with the lung’s natural ability to clean themselves of impurities. When inhaled in high concentrations, solvents may depress the central nervous system. This is called narcosis. Symptoms of overexposure range from nausea and irritability to something that resembles alcohol intoxication. Continued overexposure to particularly toxic solvents can lead to loss of consciousness, permanent brain damage and death.
Some solvents give off a strong odor when highly concentrated, while others do not. Even for those that do, you may not notice the odor after you are exposed to it for a few hours, or if you have a cold. If you notice a strong odor while using a solvent, vapors may already be too highly concentrated and you will need to ventilate more or use a supplied-air respirator. Many milder solvents are being developed to replace the more hazardous solvents. If the manufacturer of solvent claims its product can be used on the skin, you should follow instructions carefully, and wash afterward with warm, soapy water.
OSHA sets Permissible Exposure Limits (PELs) for chemicals, based on the amount or vapor level a worker can safely be exposed to in a given time period. The American Conference of Governmental Industrial Hygienists also sets exposure levels based on an 8-hour time-weighted average, called Threshold Limit Values or TLVs. These values are expressed in parts of contaminant per million parts of air.
Preventing Overexposure to Solvents
Always select the least toxic and least flammable solvent that will get the job done. Avoid solvents completely if at all possible.
Do not smoke or use equipment that may generate sparks near solvent vapors or solvent storage areas. Store solvents in tightly closed, approved containers. Store them a safe distance from any ignition source and out of children’s reach.
Use solvents only in well-ventilated areas. Bring fresh air into your shop and exhaust solvent laden air. In confined areas, wear the appropriate respiratory protection. If you can, set up a basic mechanical ventilation scheme for all projects calling for solvents.
Take special care in hot weather, when solvents evaporate quickly and are more likely to ignite.
Do not operate power machinery or climb ladders if you have been working with solvents in a confined area. If you feel drowsy, nauseated, *high* or irritable while using solvents, immediately move to an area of fresh air. First aid for unconsciousness resulting from overexposure to solvent vapors is fresh air.
Solvent and Dust Fire Hazards
Most solvents are extremely flammable. By themselves, in paints, or other products, solvents cause many shop fires. The fire hazards that solvents pose may be their greatest threat, to both human health and property. You must follow basic shop safety rules whenever you use them. Research the flash points and evaporation rates, and use adequate ventilation. Remove all ignition sources. The table below lists some important comparative health and flammability information for solvents commonly used in the shop.
An explosion can happen when solvent vapors mix with high concentrations of fine dust particles suspended in the air. Even by itself, wood dust is explosive. The finer the dust particle, the greater the chance of explosion. Also, as temperatures increase, an explosion can happen at lower solvent vapor concentrations. One worker, hand sanding, could not raise enough dust to cause an explosion, but several people operating power sanding equipment could.
An open flame can set off an explosion, as can an accidental charge of static electricity or a spark from a combustion engine, light switch or power tool. Some fine powders and fillers can generate enough static electricity to ignite a flammable atmosphere. When handling large quantities of powdered material, keep airborne concentrations to a minimum and use grounding devices on transfer equipment.
Common Shop Dusts
Dust from partially cured epoxy can cause respiratory problems if inhaled, and dermatitis if allowed to settle on skin. Dust from fully cured epoxy is chemically inert and considered a nuisance dust from a health hazard standpoint. However, enough cured epoxy dust suspended in the air could create a combustible dust atmosphere.
Dust from woods commonly used with epoxy, such as cedar, redwood, mahogany and teak, can cause allergic skin and respiratory reactions. Wood saps and oils contain irritants. These allergens are reduced as lumber dries, so it is always better to work with seasoned wood.
Dust from minerals, such as asbestos and crystalline (not amorphous) silica are dangerous because of their shape, which makes them difficult to expel from the lungs. This is also true of airborne glass, carbon and similar fibers, coming from cutting and handling glass tape or cloth, or from sanding or grinding a fiberglass composite. Use these materials only with adequate ventilation and appropriate respiratory protection, such as an approved particulate dust mask. For comfort and safety, avoid inhaling these dust!
Preventing Overexposure to Dusts
The following sensible shop suggestions may help to reduce exposure to epoxy dust, wood dust and fillers.
- Use personal protective equipment if you handle wood you suspect that you may be particularly sensitive to.
- Sand only in shop areas with adequate ventilation. If dust levels in your shop are high, or if you are sanding in a confined space for a long time, wear an approved dust mask. If the entire shop is dusty, make sure everyone—not just the person sanding—wears a mask.
- When you have a choice, use a cutting tool, a chisel or plane, rather than an abrading tool, a polisher or sandpaper. Wear safety glasses.
- Use wet, rather than dry, sanding techniques on epoxy. When sanding fresh epoxy, wait for several days to ensure a complete cure. If you can’t wait to sand, wear protective clothing, eyewear, and a dust mask.
- If you must sweep your floor, wear a dust mask and use a sweeping compound. It is safer to vacuum or mop because less dust goes into the air.
- Use dust collectors on major dust producing machinery.
- Take steps to prevent fires. Store solvents safely and make rules about smoking. Dust, solvent vapors, and an ignition source can make an explosive combination.
- Prevent conditions that could create a static electrical charge. If handling large quantities of dust or filler, ground equipment properly.
- When handling fillers, try to keep them from becoming airborne, where they can remain respirable for long periods.