Six Classes: A New Way to Eliminate Harmful Chemicals

The Green Science Policy Institute has launched an innovative approach to reducing hazardous chemical use aimed at accelerating the use of safer chemicals and thus healthier products.

The Six Classes approach classifies chemicals with major health concern into the following six categories: highly fluorinated; antimicrobials; flame retardants; bisphenols and phthalates; some solvents; and certain metals. Instead of focusing on individual chemicals, the Six Classes approach groups chemicals that have similar structure, use, or properties.

By saying all chemicals in the listed classes should be avoided, the idea is to avoid “regrettable substitutions” which occur when a banned chemical is replaced with a similarly structured and thus often similarly dangerous chemical. In this way, instead of proceeding chemical by chemical, once a single chemical in the class is proven hazardous, the entire class is avoided.

The institute has produced short videos explaining the different classes. Links are below as we review each category of chemicals.

Highly Fluorinated Chemicals

Highly fluorinated chemicals are compounds used to make products stain, water, and stick resistant. There are more than 3,000 highly fluorinated chemicals on the market today. Chemical exposure is from  waters polluted during manufacturing processes and the migration of these chemicals from consumer products into the air, household dust, and food.

While the functionality of these chemicals may be convenient, they are known to cause serious health impacts and can last in the environment indefinitely. One of the most commonly used highly fluorinated chemicals is PFOA or perfluorooctanoic acid. Studies link this chemical to kidney and testicular cancer, elevated cholesterol, decreased fertility, thyroid problems, and decreased immune response to vaccines in children.

Be careful when products claim to be “PFOA free” as often they contain similarly dangerous chemicals. To best avoid highly fluorinated chemicals, do not buy products advertising water or stain repellency properties.

In the building products sector, highly fluorinated chemicals can be found primarily in:

  • Carpet and tile flooring;
  • Adhesives, sealants and caulks;
  • Paints; and
  • Wood floor finishes.


Antimicrobials are an increasingly popular additive used to kill or inhibit the growth of bacteria and mold. Also referred to as antibacterials or biocides, these substances are regulated as pesticides. Both the Centers for Disease Control and Prevention and the Food and Drug Administration conclude that adding antimicrobials to products is unnecessary. Kaiser Permanente, a major health care system, announced in 2015 that is would no longer use interior building products containing antimicrobial chemicals. Antimicrobials should not be confused with alcohol-based cleansers like hand sanitizer.

One well known antimicrobial—Triclosan—was banned by the FDA from soaps, but the ban includes 18 other chemicals few could name and doesn’t apply to products outside the FDA’s jurisdiction, including building products. Many products often do not advertise antimicrobial properties because the chemicals are included as a preservative for the product, not marketed as a feature for consumers.

Antimicrobials are associated with hormone disruption, developmental and reproductive effects, allergen sensitivity, antibiotic resistance, asthma, dermatitis, and allergies. These chemicals can be absorbed through skin contact or ingested via contaminated dust – in fact nearly every dust sample analysed worldwide contains antimicrobials.

In the building products sector, antimicrobials are frequently added to:

  • Paints;
  • Carpet and wood flooring;
  • Wallcoverings;
  • Toilet seats;
  • Door hardware and handles;
  • Countertops; and
  • Cellulose insulation.

Flame Retardants

While flame retardants sound well intentioned, they are persistent bioaccumulative toxics that can lead to severe human health effects. Today smoke detectors and sprinkler systems are more effective and healthier ways to protect homes.

Halogenated flame retardants are treated with chlorine or bromine. They are persistent, bioaccumative toxicants associated with liver, thyroid, developmental, and reproductive cancer. Flame retardants are absorbed by humans through skin contact, ingesting dust, and breathing in air polluted with chemical off-gassing.

In the building products sector, flame retardants can be found in:

  • Foam insulation (spray and board) and sealants;
  • Carpets;
  • Floor coatings; and
  • Flame retardant paints

Bisphenols & Phthalates

Bisphenols and phthalates are chemicals used with plastics. Bisphenols make plastics stronger or create a protective coating while phthalates make plastics more flexible. Most PVC-based products contain phthalates as an additive to the core polyvinyl chloride plastic compound.

These chemicals are known to mimic or block hormones, which can severely disrupt vital body systems. Even at low levels, they can have lasting health effects, especially for young children and fetuses. Bisphenol A has been linked to asthma and neurodevelopmental problems. Phthalates can cause asthma, allergies, and cognitive and behavioral problems, and is likely to be a human carcinogen.

Reaching out to manufacturers and retailers to demand bisphenol- and phthalate-free products drives innovation and increases the supply of healthy products. For example, Kaiser Permanente’s Environmentally Preferable Purchasing Program committed to purchasing PVC-free carpet to reduce the risk of phthalates. This sent a ripple effect across industries because Kaiser’s considerable purchasing leverage demanded supplier transparency and lowered prices of safer alternatives.

In the building products sector, phthalates often are in:

  • Vinyl flooring;
  • Carpet backing;
  • Wall coverings;
  • Roof and waterproofing membranes;
  • Paints and coatings; and
  • Adhesives, sealants, caulks and glues

In the building products sector, Bisphenol A often is in:

  • Epoxy resins (used to make epoxy paint coatings, adhesives)

Some Solvents

Solvents are a diverse group of chemicals used to dissolve, suspend or extract other materials. The solvents at risk of harming human health are organic solvents, which are carbon-based compounds.

The main health concerns of solvents are due to the vapors that evaporate from products as they are used. Some solvents can off-gas these vapors for years. Solvents have been linked to leukemia, lung cancer, and adverse neurodevelopmental effects. Short-term acute exposure to methylene chloride can lead to asphyxiation or death.

In the building products sector, hazardous solvents typically are found in:

  • Paints, coatings and paint strippers;
  • Wood floor finishes; and
  • Adhesives, sealants and caulks.

Certain Metals

Metals such as arsenic, mercury, cadmium and lead are highly toxic. They often are used as stabilizers in vinyl used in wire insulation and other PVC products but also are used in roofing, solder, radiation shielding, and in dyes for paints and textile.

Health concerns of heavy metals include impaired brain development, increased cancer risk, and adverse effects on the nervous and cardiovascular systems. Cadmium is a carcinogen and has been found to damage the kidney and lungs. All these health impacts are of even greater concern to children and pregnant women.

Though industry has lowered its reliance on heavy metals, they impact human health at low levels of exposure. Heavy metals also can be reintroduced through recycling as older metal-laden products are mixed with virgin material.

In the building products sector, Lead often can be found in:

  • Older building materials (paint, pipes, pipe fittings and solder, glazed ceramics, vinyl flooring)
  • Metal roof flashing and gutter products
  • Imported tiles

In the building products sector, Mercury often is found in:

  • Fluorescent tube light, compact fluorescent lightbulbs (CFLs) and mercury vapor type high intensity discharge (HID) lamps
  • Interior and exterior paints manufactured prior to 1991

In the building products sector, Arsenic often is in:

  • Older pressure treated wood

In the building products sector, Cadmium may be in:

  • Paints
  • Resilient flooring