Some types of paint are considered hazardous waste so they need proper and safe disposal. These types of paint can contain heavy metal (or other harmful ingredients), they can be flammable and are not suitable for reuse after long storage. Also some water based paints such as varnishes, stains, sealers etc. may contain hazardous ingredients such as mercury and so therefore are classified as chemical waste.

The use of heavy metals in paint has raised concerns due to their toxicity at high levels of exposure and since they build up in the food chain.

Another harmful material that can be found in paint is lead. Lead is normally added to paint to speed drying, increase durability, retain a fresh appearance, and resist moisture that causes corrosion. Paint with significant lead content is still used in industry and by the military. For example, leaded paint is sometimes used to paint roadways and parking lot lines. Lead, a poisonous metal, can damage nerve connections (especially in young children) and cause blood and brain disorders. Because of lead's low reactivity and solubility, lead poisoning usually only occurs in cases when it is dispersed, such as when sanding lead-based paint prior to repainting.

Primer paint containing hexavalent chromium is still widely used for aerospace and automobile refinishing applications, too. Zinc chromate has been used as a pigment for artists' paint, known as zinc yellow or yellow 36. It is highly toxic and fortunately now rarely used.

Antifouling paint (or bottom paint) is used to protect the hulls of boats from fouling by marine organisms. Antifouling paint protects the surface from corrosion and prevents drag on the ship from any build-up of marine organisms. These paints have contained organotin compounds such as tributyltin, which are considered to be toxic chemicals with negative effects on humans and the environment. Tributyltin compounds are moderately to highly persistent organic pollutants that bioconcentrate up the marine predators' food chain. One common example is it leaching from marine paints into the aquatic environment, causing irreversible damage to the aquatic life. Tributyltin has also been linked to obesity in humans, as it triggers genes that cause the growth of fat cells.

The label of an oil-based paint will say "oil-based" or "alkyd," or it will instruct you to clean brushes with mineral spirits or turpentine. Paints of this type are toxic and they can cause great damage to the environment (including humans and animals) if not disposed of properly.

Latex or water-based paint, on the other hand, is not consider hazardous waste and it can enjoy many reincarnations after its initial use. Latex paints are those that clean up with soap and water. They're very common for both interior and exterior painting. However, even this type of panit needs to be proper disposed of or recycled. Specifically, it is not advisable to pour latex paint into drains, onto the ground, or into creeks, streams or rivers. Disposing of paint this way introduces contaminants into the air, soil and ground water that can eventually work their way into the food chain.

When considering how to dispose of large quantities of unused paint, always ask for professional advice. Any reputable hazardous waste disposal service will be able to assist you.

Here are some measures you can take to reduce environmental impact of you paint consume.

Choose a low VOCs paint if possible

Volatile organic compounds (VOCs) are gases emitted by various solids or liquids, many of which have short- and long-term adverse health effects. Solvents in traditional paints often contain high quantities of VOCs. Low VOC paints can improve indoor air quality and reduce urban smog. The beneficial characteristics of such paints include low odour, clean air, and safer technology, as well as excellent durability and a washable finish. Low-VOC paint types include latex (water-based), recycled latex (water-based), acrylic, and milk paint.

The labels of paint cans can be checked for the following information:

To be considered low-VOC, the paint should contain