Are watercolor paints toxic?

After seeing some information about nontoxic alternatives to the common color Cadmium Red, I began to wonder: are watercolors toxic? Should I be concerned?

tl;dr Don’t go eating half-pans like apples, but other than that, you should be fine.

Understanding Warning Labels

For American paints, such as Daniel Smith and Da Vinci, the Art & Creative Materials Institute (ACMI) rates paints as either “AP” (approved) or “CL” (cautionary labeling). AP paints are considered nontoxic, even if swallowed. CL paints have known health hazards, and are to be kept out of reach of children under 11.

Anything sold in California (which includes paint made abroad) is also required to have a warning under California’s Proposition 65 about “significant exposures to chemicals that cause cancer, birth defects or other reproductive harm.”

Paints that are only labeled for sale outside the U.S. (for example, some Schmincke 5ml’s that I bought on the U.K. website Jackson’s) don’t have to have the ACMI seal or California Proposition 65 notice, but look for the words “Conforms to ASTDM 4236,” which means any potentially hazardous chemicals need to be identified. (If there’s no list of hazardous chemicals, it means there aren’t any. The “Conforms” message will be there regardless.)

Cautionary labeling means just that, “handle with caution,” not necessarily “don’t use.” Many paints with warning labels are in common usage. The hazardous materials are generally present in miniscule amounts, and you’d usually have to ingest them in large quantities to feel ill effects.

I think that bears repeating: you’d have to eat paints to feel the toxic effects. Simply handling them or inhaling near them is unlikely to be a problem. If you are making your own paints from scratch, you may have to think more carefully about inhalant dangers (since you’re handling raw powders), but as an end consumer who’s just painting with premade paint, the possible problems that they’re warning you about are in case of ingestion in large amounts.

Some people worry about long-term exposure or underreported dangers (toxic paints is sort of a theme in history, after all), and if it feels nicer to you to accumulate a palette of AP-rated paints, go for it! Avoidance is not the only tactic, however; if you love your Cadmiums and Chromiums, go ahead and use them with sensible precautions.

Sensible Precautions

  1. Keep potentially hazardous paints out of reach of pets or children.
  2. Don’t put your paintbrush in your mouth. Even to think.
  3. Don’t eat off the same dishes you use for paint. If you use an old plate as a paint palette, make it your dedicated paint plate, and don’t eat off it anymore. Wash it separately from your eating dishes.
  4. Don’t eat while you paint. Drinking water from a bottle should be fine as long as you don’t touch the spout with your painty hands. Drinking tea is common, but maybe not ideal, and if you ever accidentally dip your brush in your tea instead of your dirty water, that is IT. Do not drink it. Obviously. I hope. (If you go the other way around and accidentally sip your paint water… don’t panic, it’s probably fine. Just don’t like make a habit of it.)
  5. Avoid getting paint in your eyes. If you splatter vigorously, consider wearing glasses and maybe a mask, or blocking the spray from your face with paper. Don’t splatter near an open drink.
  6. Don’t douse your toothbrush. When disposing of your water in the kitchen or bathroom sink, move your oral hygiene items/dinner dishes out of the blast zone.
  7. Wash your hands after you paint. I mean wash your hands after you do anything, really.

Disposing of Wastewater

Every municipality I’m aware of considers it acceptable to dispose of dirty watercolor water by tipping it down the sink, since it contains minerals and metals in such small amounts; it’s no more toxic than greywater from the laundry machine.

Alternately, you can use it to water your flowers. The minerals found in paints are also found in the soil and may be nutritious, or just non-issues for your plants.

If you are doing plein air painting in a protected wild/Leave No Trace area, pack out your water in a sealed container as you would with food/drink or anything else. To minimize your water use and prolong its cleanliness, use your cloth as much as possible to wipe your paintbrush and only rinse with a relatively clean brush.

What ingredients should I be aware of?

The most popular watercolor binders are nontoxic (gum arabic, guar gum, honey, etc.), so any toxicity would only be from the pigments. Therefore, it varies from one color to another. Pigment toxicity usually comes from heavy metals like cadmium, cobalt, copper, nickel, manganese, titanium, and zinc. Usually the metal name will be in the name of the paint, e.g. “Cadmium Red.”

Note that if the word “hue” is used in the color name, that means that the toxic metal named isn’t actually in the paint. Think of “hue” as meaning “color of.” so “Cadmium Red Hue” doesn’t actually contain the cadmium red pigment – it’s a paint the same color as a traditional Cadmium Red, but without the cadmium.

I can confirm that Daniel Smith, Winsor & Newton, Holbein, and Da Vinci label their paints with the ACMI seal.

Schmincke Horadam paints do not use the ACMI seal, but they conform to ASTDM 4236. All of their paints warn about isothiazolinones. I looked this up, and it’s a preservative in the binder that may cause contact dermatitis (itchiness) in allergic individuals. This is one case where handling the paint may matter. If you’re itchy after using Schmincke Horadam paints, consider switching to a different brand. Most people will be immune, however.

Here are some common metals that give paints a “CL” rating under ACMI and/or a Prop 65 warning, and the colors that contain them. This is not an exhaustive list of all toxic watercolors, but it does contain all those I found in the Daniel Smith Safety Data Sheets.

Cadmium

ACMI: CL
Prop 65: Yes

Cadmium is generally the metal of greatest concern to watercolorists. It is a known carcinogen if ingested, and may cause lung damage if inhaled – in large amounts, over a long period of exposure, (my understanding: not likely if you just paint with it, more like if you made your own DIY watercolors from powders in your poorly ventilated home for years.)

Some companies, like Daniel Smith, have discontinued making cadmium colors (their Cadmium Red/Yellow/Orange Hues do not contain cadmium). But, many companies still offer them. Winsor & Newton explains on their website, “Cadmium itself is a heavy metal and is toxic but cadmium pigments are not classified as dangerous for use in line with EC classification. The level of soluble cadmium in the pigments is so low that no hazard warnings are needed and they pose no greater risk after swallowing or breathing in than other pigment types.” However, they offer cadmium-free alternatives for each of their cadmium colors.

Colors and pigments to watch out for:

  • Cadmium Red (PR 108, PR 113)
  • Cadmium Orange (PO 20)
  • Cadmium Yellow (PY 35, PY 37)

Chromium

Prop 65: Yes

Another heavy metal that can be a carcinogen if eaten, and cause lung damage if inhaled in large amount. People who work on the line in a chromium paint factory have been known to be at risk, unfortunately. Again, the amount found in watercolor paint is not generally concerning.

Found in:

  • Cerulean Blue Chromium (PB 36)
  • Chromium Green Oxide (PG 17)

Cobalt

ACMI: CL
Prop 65: Yes

Carcinogen if ingested. Some people are hypersensitive to cobalt, which can lead to asthma-like symptoms and/or skin hives.

  • Cobalt Blue (PB 28), and mixes containing Cobalt Blue including Verditer Blue and Joseph Z’s Cool Grey
  • Cobalt Teal Blue (PG 50)
  • Cobalt Turquoise (PB 36)
  • Auerolin/Cobalt Yellow (PY 40)
  • Any other paint with “Cobalt” in the name

Copper

ACMI: CL
Prop 65: No

You’re probably familiar with copper as a metal. Like many metals, it is toxic to eat in large amounts (causes vomiting, etc.), but handling it is fine and something many of us do fairly routinely. Copper is even found in trace amounts in some foods, such as crustaceans.

Found in:

  • Rich Green Gold (PY 129)

Manganese

ACMI: CL
Prop 65: Yes

Manganese is a mineral and essential nutrient; a small amount is naturally found in soil and food. Overexposure can lead to a neurological disorder called manganism that has been known to occur in ceramicists. I’m not aware of any cases involving watercolor.

Daniel Smith Manganese Hue does not contain manganese; it’s a form of phthalo blue PB 15.

Found in:

  • Manganese Blue Genuine (PB 33)

Nickel

Prop 65: Yes

Like copper, nickel is a metal that many of us are familiar with and that is found in many metal objects. Some people have a nickel allergy and handling nickel can lead to an itch or rash. (You’ll probably know if you do – you’ll have gotten it from jewelry or piercings.) For most people handling it is no problem. Eating it in large amounts is probably not a good idea.

  • Nickel Azo Yellow (PY 150). Interesting, DS Quinacridone Gold, which is a mix containing PY 150, is considered ACMI AP. I guess it’s diluted enough to be negligible at that point.
  • Titanium Yellow/Nickel Titanate Yellow (PY 53)

Titanium

Prop 65: Yes

People who have nickel allergies generally turn to titanium jewelry: it is considered hypoallergenic. Again, don’t eat it, but handling it is fine; even highly allergic people are usually okay with it. It’s found in many natural sunscreens.

Found in any paint with “Titanium” in the name (Titanium White, Buff Titanium, Gray Titanium).

Zinc

ACMI: CL
Prop 65: No

Zinc is an essential nutrient that occurs in many foods and that some people take as a supplement. It can contain nausea and stomach cramps if ingested in large amounts (as I know to my detriment after taking a zinc-containing cold pill on an empty stomach). It is not generally considered a skin irritant, and is the main ingredient in natural sunscreens.

Found in:

  • Chinese White/Zinc White (PW4)
  • Naples Yellow (PY 41)

Other Pigments

I chose to focus only on those with ACMI CL ratings and California Prop 65 warnings for this article. That may not be an exhaustive list of all substances that can irritate you. For nearly every pigment, even those labelled “AP”, I found an article describing them as an eye or skin irritant or carcinogen. And sometimes people are allergic to substances that are generally considered safe. If you find yourself reacting to a particular brand or pigment, it seems like a good idea to discontinue use. I don’t think you should worry that any pigment is causing you invisible harm.

The warnings can sound scary, but remember, they’re telling you about what can happen in an extreme cases when you’ve ingested or inhaled a large amount. It’s the dose that makes the poison. Many of these chemicals and minerals are found naturally in the earth and in our bodies in small amounts. If we stopped using every mineral, metal, or substance that could cause us harm if ingested in large amounts, we would not be able to use anything.

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