Paint and Coatings

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Did You Know?

• Commercial paints can include petrochemical solvents, pesticides, antifreeze, ammonia, phthalate plasticizers, endocrine disrupting chemicals, and even perfluorocarbon (“Teflon™”) chemicals.
• Many commercial paint companies boast that their products emit low levels of Volatile Organic Compounds. But the additional emissions from paint colorants are not typically included in their claims.
• There are paints and coatings on the market that are partially or totally based on plant-derived chemicals.
• There are paints on the market that are mineral-based and use no or almost no petrochemicals.
• There are paints on the market that actually improve air quality.

Paint & the Environment

If Walls Could Talk

Paints have historically been used to protect wood, metal, and other surface materials from the elements, or to add aesthetic attraction.  Until the 20th century, these coatings were milk-based or plant-derived, and usually (relatively) benign.  But the advent of modern manufacturing mainly employs petrochemicals for this purpose, some of which can be toxic, in addition to other chemical additives that also have inherent danger.

In 2017, the American Coatings Association estimated 800 million gallons of architectural paints and coatings were sold in the U.S. The volume used just in Austin would cover 32 square miles, 12% of the city’s entire land area.  The volume used nationally would cover 11,478 square miles, enough to color the state of Maryland. 

Toxins in Paint

In the known list of ingredients in various types of domestic and industrial paint, there are 18 known carcinogens, 6 probable carcinogens, and 22 possible carcinogens (though many of these carcinogens are more frequently found in commercial, industrial, and infrastructure applications than residential ones).   It should therefore be no surprise to find high incidences of bladder and lung cancer in professional painters.  (International Agency for Research on Cancer, Chemical Agents and Related Compounds, 2012, p. 519.)

Given these chemical hazards, there is also no surprise of a positive association between maternal exposure to painting (including pre-conception and pregnancy) and leukemia in their children.

Paints and coatings basically have 4 components: a resin, a pigment, a solvent, and additives.  The resin usually is mixed with a pigment for color.  Depending on the ingredients, all of these can be toxic to people and animals in or near buildings where they are applied, as well as harmful if they are released to the general environment.

Watching Paint Dry: Volatile Organic Compounds

Solvents, resins, and some additives emit fumes (or “offgas”) as they dry.  Depending on the product, these Volatile Organic Compounds (VOCs) can offgas for weeks and sometimes years at reduced levels after application.

Studies demonstrate children exposed to VOCs at high levels are four times as prone as adults to develop asthma. (Rumchev, K., et al. Thorax, V. 59, 2004, pp. 746-751.)  Other studies show a link between VOCs and childhood asthma.   (Indoor Air Pollution in California, California Air Resources Board, February 2005.)

In 2013, the California South Coast Air Quality Management District identified 338 distinct VOCs emitted from paint in the state, amounting to 19 million pounds of annual emissions.  To give a relative sense of the harm, the Directory looked at the top 17 chemicals (Chart P1) that make up 80% of this total volume.  About half of this quantity is made up of chemicals used as solvents.

While acute health effects are dependent on the dose, frequency, and individual tolerance, the chart indicates caution should be used when applying paint.  Some of these VOCs are relatively benign.  One, propylene glycol, is actually used as a food preservative.  But others can cause symptoms related to chemical illness such as sinus irritation, difficulty breathing, dizziness, nausea, and drowsiness. If exposed repeatedly or for a long period of time, some can be carcinogenic, neurotoxic, endocrine disruptive, and cause developmental and reproduction problems.

VOCs are also an air quality hazard to the larger environment.  Paint emissions eventually migrate into the atmosphere.  They can combine with nitrogen oxides to create ozone pollution.  2014 data from the Texas Commission on Environmental Quality showed that about 2% of all state VOC emissions from human sources came from paint.

There is some good news in that, over the past 25 years, most paint manufacturers have developed products that greatly reduce or completely eliminate VOCs.  In the past, 250 grams of VOCs per liter was considered common.  Most of today’s interior paints emit no more than 50 grams per liter.  However, there are many paint products with emissions between 0 and 10 grams per liter.

This is a relative thing though, as darker colored tints often increase stated VOC levels measured in interior base paint, some by as much as 50 grams per liter.

Part of the reason for the reduction in VOC content is the paint industry’s switch from chemical- to water-based solvents.  About 90% of total U.S. paint volume in 2017 was water-based.

Leaden Legacy: Metal and Mineral Toxins

Toxic metals and minerals have historically been used in various paint products.  While the U.S. government has gradually recognized the harm from these substances and phased out their use through regulation, painted surfaces and products with these hazardous substances can be found in older buildings throughout the country.

Lead is the most well known of them.  It was used for pigments, as well as for primers and driers, as far back as Colonial times.  Its use in U.S. home paint products was reduced by a voluntary standard in 1955.  A mandatory limit of 0.06% by weight was subsequently created in 1978.  This limit was further decreased to 0.009% in 2009.

However, the legacy products used in older homes before 1978 can still cause harm, particularly to children. Paint chips tainted with lead can break off and be eaten by them.

Lead particles from deteriorating paint can attach to house dust, and be inhaled, or ingested by anyone, though young children are more vulnerable because they frequently place their hands in their mouths.  And degraded lead paint on the outside of homes can leach into soil that adults garden on and children play on.

U.S. National Center for Health Statistics data from 2011-2016 revealed that 1.2% of children under 6 years old had over 5 milligrams of lead per deciliter of blood. Every milligram of lead shaves one IQ point from these children.

The U.S. Dept of Housing and Urban Development  estimated that in 2006, 37 million homes (26% of all U.S. housing units in 2019) had some level of lead contamination.  Some 23 million of these were significantly contaminated.   

Lead has been known to be a poison for thousands of years.  At high levels, it can lead to lethargy, convulsions, coma, and even death.  It can also cause anaemia, hypertension, kidney impairment, endocrine disruption, and toxicity to the reproductive organs.  At low levels in children, it can act as a neurotoxin to cause reduced attention span, increased anti-social behavior, lower academic performance and IQ levels, and affect the endocrine system. It can also cause anaemia, hypertension, kidney impairment, endocrine disruption, and toxicity to the reproductive organs. The neurological and behavioral effects of lead are believed to be irreversible.

Mercury was used as a biocide in interior paint until mid-1990, and in exterior paint until 1991. Similar to lead, children can be exposed to mercury via paint chips, house dust, and outside soil, though there is limited evidence to suggest that the quantity and impact of exposure is greatly reduced compared to lead.  (Chemosphere, 2008, pp. 882–885.)

The largest health problems attributable to inorganic mercury are kidney dysfunction and acrodynia.  Mercury ingested by nursing mothers can be transferred to infants.  Animal studies indicate long-term oral exposure to inorganic mercury salts causes kidney and nervous system damage, affects blood pressure and heart rate, and creates digestive disorders. Immune system reactions can also occur.   

Asbestos was used by several companies as a filler in textured paint, and other specialty paints, until 1990, when regulation prevented its use.  It was also used as a filler in various wall texture products that paint was applied on.  If asbestos fibers are broken loose, they can become airborne.  If the exposure is great enough, they can cause lung cancer.

Cadmium and chromium pigments can also appear in legacy paint.  Nickel has also been identified.  These are carcinogenic at sufficient doses, and each of them have various other health consequences.  Again though, these metals usually appear in small quantities compared to lead.

Other Additives

Paints usually have additives that can cause harm to the environment and people exposed to them.  Antimicrobials or biocides, (including algaecides, mildewcides, and fungicides) are added to paint to keep bacteria from impairing its quality, longevity and durability.  These chemicals are registered pesticides, and can cause adverse reaction in chemically sensitive people, as well as chronic, long-term health damage to less sensitive people, and harm to the general environment.  Other additives include antifreeze, antisettling agents, fillers, catalysts, curing agents, driers, emulsifiers, fire retardants, plasticizers, and thickeners.  Some of these chemicals and compounds can also be hazardous.

Antimicrobial pesticides (biocides) are used in most paints as a preservative in the container, as well as to prevent bacteria, algae, mold, and mildew and other fungus in the applied coatings over time.  This is particularly important for outdoor paints that are designed to withstand the elements for many years, and for indoor paints in humid environments such as bathrooms and kitchens.

There are two basic kinds of biocides in products: “in-can,” which acts as a preservative while the product is inside a paint can; and “dry film,” which protects the product after it is already applied.  Depending on the product and the purpose, in-can biocides can make up between 0.05 and 0.5% of paint by weight, and dry-film can make up between 0.15 and 3% of paint by weight.  (“Industrial Biocides, U.S. Product Guide,” ISP Corporation.)

Biocides used on outdoor paint will leach off over time.  A small percentage of this run-off will end up in the watershed, with possible harm to aquatic species and ecosystems.

There are dozens of different biocides used in the paint industry.  While some are relatively benign, many have potential to cause harm.  Chart P3 gives a relative sense of the effects of certain biocides on health and the environment.  Limiting these toxins to the greatest extent possible is a prudent strategy.

Some specialty paint products specifically eliminate biocides as additives, but care has to be taken as to: 1) where they are applied (paint longevity in humid areas may suffer without them); and 2) avoiding contamination of the paint can (pouring the paint that is used in a tray rather than using the paint directly from the container will limit cross contamination from the paint brush); 3) dealing with a reduced shelf life of the product.

Almost all mainstream paints use biocides.  However, the name and percentage of weight may not be listed.  Contacting the manufacturer may be required to get more information.  (Some manufacturers  may not be completely forthcoming because of trade secrets.)

Ammonia, employed as a paint dryer and antimicrobial, has replaced chemicals that offgas VOCs.  Though it evaporates relatively quickly, with enough exposure, it can cause inflammation of the sinus and upper respiratory tracts.  It can also be a severe irritant to the skin and eyes, and act as a sensitizer to magnify harmful effects of other chemicals.

Antifreeze is used to ensure storage life.   Ingestion or repeated absorption through skin can cause damage to kidneys, liver, and the central nervous system, as well as adverse reproductive effects and birth defects based on animal tests.

Alkylphenol ethoxylates (APEs) are surfactants that stabilize and improve a paint’s ability to coat the surface, while also increasing shelf life.  This class of chemicals includes nonylphenol ethoxylates (NPEs) and octylphenol ethoxylates (OPEs).  They break down into chemicals that are persistent in the environment, bioaccumulate in the food chain, are acutely toxic, and endocrine disruptors.

Fluoropolymers, which add the element fluorine to the petrochemical carbon paint base, are used in paints for commercial buildings and high-end residential homes.  These “Teflon™” perfluorocarbons (PFCs) produce a highly durable coating, most frequently used on metal roofs and wall facades, which is resistant to oil, water, salt corrosion, chemicals, dirt, UV radiation, and to a degree, even graffiti.  They can also reflect and insulate from heat to make the building more energy efficient.

Unfortunately, their high durability makes them ecologically suspect.  They do not biodegrade easily, persisting in the environment.  Biological traces of PFCs have been identified around the world in the bodies of most people and wildlife that have been measured, even in remote regions like the Arctic.  They appear with more frequency though around sites where they are manufactured or used as an ingredient in products, and at sites such as airports where they were historically used to extinguish fires.

Health effects associated with exposure to certain PFCs include high cholesterol, increased liver enzymes, decreased vaccination response, thyroid disorders, pregnancy-induced hypertension and preeclampsia, and testicular and kidney cancer.

Over time, some of the coating is likely to sluff off due to the elements or building maintenance.  While the author does not know of any studies to show localized contamination from fluoropolymer paints, the harmful chemicals will be released into the larger environment, in addition to the toxins emitted in the original manufacture of them.

Phthalates, used as plasticizers, were once often employed in paint products.  Some of these chemicals can be carcinogens, developmental and reproductive toxins, endocrine disruptors, and environmental toxins.  While their use is now discouraged by the paint industry, phthalates can still be found in certain specialty products such as anticorrosion coatings.

More worrisome is their use in legacy paints.  As an example of their harmful effects, phthalates in house dust have been associated with behavioral changes in children such as problems in communication and increased hyperactivity.  (Philippat, et al., Environmental Health, June 26, 2015.)

Short chained chlorinated paraffins (SCCPs) are organochlorines used as plasticizers and flame retardants in certain specialty paints.  Like PFCS, they are persistent bioaccumulative toxins, and can be found in the bodies of humans and wildlife worldwide.  They are toxic to aquatic organisms at low concentrations, and a possible human carcinogen.

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Painting the Town Green

The chart below depicts a relative hierarchy of how different classes of paints perform in regards to health and the environment.

Natural Paints, Stains, and Varnishes: Some commercial coatings are made with all-natural or partially natural ingredients, including vegetable oils, plant resins, minerals, plant and earth pigments, and milk.  Some manufacturers make their products with 100% natural ingredients, while others mix least-toxic synthetic solvents with their brands.  These coatings are often durable and wash easily.  But they can cost 2 to 3 times that of conventional products due to the cost of materials, the small scale of the manufacturers, and the fact that some of them are imported.  The variety of colors is not always as great as conventional paints, and they are available only by mail order or through a few specialty stores.  See Chart P5.

Low-Biocide/Low-Additive Paints: Some coating products use conventional synthetic materials, but reduce or eliminate toxic additives that make them unbearable to chemically-sensitive people and somewhat harmful to the general public.  These paints reduce or eliminate exposure to biocides and fungicides that are normally put in paints to preserve them from bacteria, mold, mildew, and insects, and that protect the painted wood.

These paints will usually have no- or low-VOCs, and also avoid other conventional additives like ammonia and antifreeze.  Some of these products may supplement their ingredients with biobased materials.  These paints have similar quality characteristics compared to conventional products, and some brands provide a wide array of colors.  But the shelf life is greatly reduced, particularly after the can is opened.  And these paints may be difficult to use in areas of high humidity, like bathrooms, or exteriors in wet climates, because they are susceptible to attacks by fungus and mildew.  A problem with this category is that there is no independent rating criteria for “least-toxic paint,” or third-party organization to enforce such a criteria if it existed.  Consumers are advised to order samples to determine how it affects them personally.  See Chart P6.

Mineral-Based Paints: There is a growing niche market for coatings that employ minerals instead of organic resins as a coating.  Liquefied potassium silicate, often mixed with mineral pigments, can be used on both interior and exterior walls to create a durable “waterglass” paint.  Unlike organic resins that can eventually wither with moisture, temperature, and UV radiation, mineral-based paint bond with the substrate it is applied to and can last for decades.  There are some buildings in Europe where the coating has stayed intact for over a century.

The paint is permeable, allowing the walls to breathe, with zero VOCs.  Since it is not organic, it is mold, mildew, and algae resistant, eliminating the need for biocides.  Any unused paint from the application solidifies as pure minerals and is non-toxic.

Most of these products are applied to mineral-based building materials such as stone, brick, plaster, and cement, but variations can also be used for wallboard and wood.  (Products appropriate for wood use a small amount of organic ingredients.)  See Chart P7.

Paint with No Alkylphenol Ethoxylates and Low VOCs:  Conventional paint that emits low VOCs without the addition of endocrine disrupting chemicals is considered a high standard.  Green Seal, a third-party certification organization for environmental products, currently has a “GS-11” standard for such paints.  Unfortuntaely, only one company has officially attained this status with some of its products, and only one other company has produced no-APE/low-VOC products (without verification).  See Chart P8.

Air Purifying Paints: As air quality became a larger environmental concern over the last few decades, paint companies began making products with very low or no VOC emissions.  However a few companies have gone even further by offering paint that actually eliminates VOCs emitted from other sources.

Used indoors, these products remove emissions from sources such as carpets, furniture, cleaning chemicals, and indoor combustion such as gas stoves.  Outdoors, they can reduce emissions from autos and industrial sources.  One of the side benefits of this paint class is that it keeps the exteriors of buildings as well as the infrastructure on the sides of highways (such as walls, bridges and tunnels) cleaner.  This technique can be used in either organic or mineral-based paints.

There are two different chemistries to achieve this.  One is a photocatalytic process using a form of titanium dioxide.  In the presence of natural light and some forms of artificial light, the catalyst degrades noticeable percentages of VOCs, ammonia, carbon monoxide, as well as airborne bacteria and fungi, into nitrates, carbon dioxide, and water vapor.

Some products in this paint class have their flaws.  In organic-based paints, the catalyst can wear away over time, particularly when exposed to the weather.  The catalyst can also attack organic paint itself even when indoors, shortening the life of the paint and making the photocatalyst less effective.  However, Keim, the producer of a mineral-based photocatalytic paint, believes little or no degradation will occur because the catalyst is protected by the product’s water-glass finish, and because there is little organic material in the coating to begin with.

The second approach uses a non-toxic zeolite “tube” or crystal that allows smaller molecules to pass through it unimpeded while trapping larger VOC molecules in the lattice.  This approach can also degrade over time as the paint becomes saturated.  At least one of the U.S. suppliers suggested that a new coat of this paint be applied every 2 to 7 years for optimal air-purifying effectiveness.  (The frequency of reapplication is dictated by the amount of pollutants in a given location.)

Tests for this paint class have shown measured VOC reductions on both a generic and individual product level in laboratory tests as well as real-world building interiors and exteriors, removing between 10 and 100% of various pollutants.

Chart P9 lists products in this paint class sold in the U.S.

Least-Toxic Paint Removers: Certain chemical paint stripper ingredients are highly toxic.  Among the most dangerous is Methylene Chloride.  This chemical can cause severe burns to the skin and eyes, and irritates sinuses and the respiratory tract.  It is acutely toxic to the central nervous system, causing dizziness, nausea, memory loss, and even death at high dosages.  It has been linked to more than 60 deaths in the U.S. since 1980.  Further, it is damaging to internal organs, carcinogenic, and mutagenic.  There is limited evidence that it causes spontaneous abortions.   It is also flammable.

N-Methylpyrrolidone (NMP) dangers include being a developmental toxin that can cause miscarriages and stillbirths.  It can cause decreased fetal weight, which can lead to developmental problems throughout a child’s life.  NMP can also cause weight reduction, kidney and liver toxicity, and neurotoxicity.

Several major chain stores, including Home Depot, Sherwin-Williams, and Lowe’s, announced that they were phasing out or banning sale of Methylene Chloride paint strippers by the end of 2018.  These chains also would not sell or were phasing out the sale of paint removers with NMP.

Chart P10 contains a list of least-toxic chemical paint removers reviewed by the South Coast Air Quality Management District in California.  The District recommends against Methylene Chloride and NMP as ingredients.

Low-VOC Paints: VOC emissions have plummeted since they first became a concern in the 1980s.  Today, almost all major paint manufacturers offer products with low- or zero-emissions.  However, the reduced emissions are often for the base and not the tints.  The products in Chart P11 include paints with rated emissions generally between 0 and 10 grams per liter inclusive of VOCs emitted from colorants.  Consumers should verify this with the manufacturer or dealer at time of purchase.

Recycled Paints: Americans generate between 50 and 130 million gallons of leftover paint each year.  Many cities and several private companies collect unused but still usable paint and reblend it with virgin paint or factory seconds to sell as an inexpensive primer.

Many brands have limited color palettes, though some companies have expanded color palettes for more general use.  While recycling prevents resources from being disposed, recycled paints can emit VOCs several times higher than most new products on the market today, and still retain toxic additives that newer products have reduced or eliminated.  Chart 12 contains a list of some of these products.

Not Recommended

Specialty Paints: Some paints that target niche markets contain ingredients that are more toxic than common paint.  Chlorinated paraffins, which are possible carcinogens, are used to create fire resistance.  “Dry-Erase” paints contain isocyanates, which are asthmagens.  Magnetic paint can contain solvents that damage the central nervous system.  These and other specialty paints with high chemical risks should be avoided.

Antimicrobial Paints: Another kind of specialty paint adds extra levels of biocides.  Many consumers infer that this will kill more disease causing pathogens.  In fact, it is possible that pathogens will actually mutate and become resistant to biocides and antibiotics from this wanton chemical use.  Meanwhile, people themselves may be vulnerable to the effects of these biocides, and pay a monetary premium for the privilege.

Legacy Paints with Lead: Unlike other undesirable products listed in this article, one cannot buy lead paint today.  Rather, it is embedded in significant doses in the structures of about 16% of residences in the U.S.  If the building was constructed before 1978, there is a risk that it could be contaminated with lead paint.  While this can potentially be dangerous to anyone, in the particular cases of pregnant mothers and small children, it could cause health problems if action is ignored.

There are 4 techniques for lead abatement in homes.

• Encapsulation covers lead-coated surfaces with another coating that acts as a barrier to hold the lead in place; it keeps it from migrating to the indoor or outdoor environment.

• Encasement covers lead-coated surfaces with uncontaminated building materials such as new wallboard.

• Removal of building materials replaces house parts contaminated with lead paint.

• Removal of lead paint on existing building materials extracts lead from inside the building.

These various techniques have advantages and disadvantages, and may not be suitable in all situations.  Removal of lead paint inside buildings is expensive, requiring isolation of the affected area, along with workers that don HazMat suits who are equipped with gloves and respirators.  As a rule, encapsulation is the least expensive strategy.

Chart P13 contains a list of encapsulation products and paints that act as a lead-paint barrier.  In general, they are best applied by trained specialists.  Note that some building materials that have constant wear are not appropriate for encapsulation.  For instance, windows and doors generate friction when they are opened and closed, which will wear away encapsulants and re-expose the old lead coatings.  These materials are often candidates for removal.

Also, encapsulants must be periodically inspected and maintained if the barrier is marred or damaged.

Fluoropolymer (Teflon™-like) Paint: Fortunately, these products are not widely used in the residential market, but when encountered, they should be rejected because of their adverse health and environmental effects.

As well as chemical hazards, people using oil paints and paint solvents (including plant-based formulas) should be aware of the hazards of auto-oxidation.  Rags and paint application materials soaked in these liquids can literally autocombust under certain situations.  One way to mitigate this is to soak these materials in water, and then place them in a sealed plastic bag for disposal.

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