Bioaccumulative Substances

It’s well known that many materials have the potential to be toxic: they leach chemicals into the air and water, having massive ramifications for wildlife, the environment, and human health. One especially harmful group is Persistent Bioaccumulative Toxic substances, also called PBTs.

What are PBTs and Bioaccumulative Susbtances?

PBTs are:

Persistent: Decompose very slowly in water and soil
Bioaccumulative: Accumulate in living organisms
Toxic: Pose the risk of cancer, mutations, reproductive issues, or other adverse health effects

What is Bioaccumulation?

Bioaccumulation is when a chemical gradually builds up in the system of an organism.

For example, if plankton absorbs chlorinated water, the concentration of chlorine in its system will gradually increase. The animals that eat that plankton will also accumulate chlorine, and the concentration will increase the higher the animal is on the food chain. Consequently, even if the initial concentration of chlorine wasn’t very harmful, a bioaccumulative substance could have devastating effects on humans and the ecosystem over time.

Which Bioaccumulative Substances are Restricted?

Persistent Organic Pollutants (POPs)

Persistent organic pollutants are a class of PBTs that’s largely made up of halogenated organic molecules. They often come from pesticides, industrial processes, and combustion.

POPs are very bioaccumulative substances. Because halogenated compounds are soluble in lipids, they get readily absorbed into fatty tissue.

In addition, an especially harmful aspect of POPs is their volatility. They evaporate readily from soil and plants – rarely degrading in the atmosphere due to their stability. As a result, they can travel to remote places like the Arctic, harming both the wildlife and the indigenous peoples that hunt for food.

POP Hazards

POPs are very toxic, even at low levels.

Some of the hazards associated with POPs are:

Death
Chronic illness
Cancer
Fetal development
Disruption of the reproductive, immune, and nervous systems

How are POPs Regulated?

In 2001, a global agreement called the Stockholm Convention was put into place by the United Nations Environment Programme. It originally listed 12 chemicals, mainly pesticides, and has since expanded to include plastics, flame retardants, industrial chemicals, and more.

About 179 countries have signed this agreement, including Canada, China, and the European Union. Learn more about POP regulations.

TSCA PBTs

The Toxic Substances Control Act (TSCA) regulates toxic substances in the United States. In 2021, the Environmental Protection Agency (EPA) issued heavy restrictions on five known PBTs under TSCA section 6(h):

Phenol, isopropylated phosphate (3:1) (PIP (3:1))
Decabromodiphenyl Ether (DecaBDE)
Pentachlorothiophenol (PCTP)
2,4,6-Tri-tert-butylphenol (2,4,6-TTBP)
Hexachlorobutadiene (HCBD)

Learn more about the TSCA section 6(h) restrictions.

What are the Regulatory Requirements of these Bioaccumulative Substances?

If you are manufacturing, processing, or distributing any of the above chemicals, you must keep records proving your compliance with their regulations. You must keep these records for at least three years, and you must be able to submit them within 30 days upon request.

If you ever need assistance with recordkeeping, Safety Data Sheets, or other environmental compliance issues, contact Enviropass for a free consultation!

Keep reading to learn more about some of the restricted bioaccumulative substances.

Phenol, isopropylated phosphate (3:1) (PIP (3:1))

Phenol, isopropylated phosphates (3:1) are a large group of substances, each with slight variations in their chemical makeup. What they all have in common is three aryl groups (the rings), each with at least one isopropyl group. That is where the (3:1) comes from – three aryl groups with one isopropyl group each.

Some examples of PIP (3:1) compounds are:

Tris(3-isopropylphenyl) phosphate
Tri(isopropylphenyl) phosphate
Tri(4-isopropylphenyl) phosphate

Applications of PIP(3:1)

PIP(3:1) compounds comprise a relatively large group of chemicals. As such, they have a wide variety of uses, including:

Adhesives
Hydraulic fluids
Resins
Flame Retardants
Lubricants
Plasticizers

The most common industries that use PIP(3:1) compounds are electronics, transportation, construction, and furnishings.

PIP(3:1) Hazards

Some hazards associated with this substance are:

Toxic to aquatic plants, aquatic invertebrates, sediment invertebrates, and fish
Potential for reproductive, neurological, and developmental effects
Potential for effects on adrenals, liver, ovary, heart, and lungs

Decabromodiphenyl Ether (DecaBDE)

Decabromodiphenyl ether belongs to a group called polybrominated diphenyl ethers (PBDEs). As the name suggests, DecaBDEs have ten bromine groups and pose a significant environmental risk. In fact, it has an estimated bromine content of 83%.

DecaBDE is an additive flame retardant – it gets added to a substance by mixing. That is in contrast to reactive flame retardants, which must chemically react to have the same effect. Thus, additive flame retardants are much more convenient to use. Unfortunately, this also means that the chemicals in additive flame retardants are more likely to leech out into the environment.

Applications of DecaBDE

Rubber, plastics, and polystyrene are common materials that have DecaBDE.

Some common uses are:

Computers
Televisions
Circuit boards
Cable insulation
Upholstery fabric (automobiles, aircraft, Etc.)
Mattresses
Wood used in construction

DecaBDE Hazards

Some hazards associated with this substance are:

Toxic to aquatic invertebrates, fish, and terrestrial invertebrates
Potential for developmental, neurological, and immunological effects
Developmental toxicity
Liver effects
Carcinogenicity

Pentachlorothiophenol (PCTP)

Pentachlorothiophenol is an aromatic ring substituted with one thiol group and five chlorine groups. The thiol group makes this compound a very effective cross-linking agent.

Applications of PCTP

PCTP has been used as a peptizer to increase the flexibility of rubber. Specifically, this compound is added during the manufacturing process to decrease the viscosity of the material.

PCTP Hazards

Some hazards associated with this substance are:

Toxic to protozoa, fish, terrestrial plants, and birds
Potential for liver and reproductive effects

2,4,6-Tri-tert-butylphenol (2,4,6-TTBP)

2,4,6-Tri-tert-butylphenol is a phenol substituted with tert-butyl groups at the 2, 4, and 6 positions. 2,4,6-TTBP is often used as a reactant or intermediate to synthesize other molecules, such as 2,6-di-tert-butyl-4-methoxyphenol.

Applications of 2,4,6-TTBP

Some uses of 2,4,6-TTBP are:

Fuel additive
ubricating grease
Analytical standard
Antioxidant in plastic and resins

2,4,6-TTBP Hazards

Some hazards associated with this substance are:

Toxic to aquatic plants, aquatic invertebrates, and fish
Potential for liver and developmental effects

Hexachlorobutadiene (HCBD)

Hexachlorobutadiene is a diene that has six chlorine substituents. Unlike the other substances in this list, HCBD mainly shows up as a byproduct when producing chlorinated hydrocarbons.

Some of the products that generate HCBD are:

Perchloroethylene
Trichloroethylene
Carbon tetrachloride
Magnesium (via electrolysis)

Applications of HCBD

Some uses of HCBD are:

Plastic additives
Protective coatings
Analytical standards
Chlorine recovery

HCBD Hazards

Some hazards associated with this substance are:

Toxic to aquatic invertebrates, fish, and birds
Possible human carcinogen
Potential for renal, reproductive, and developmental effects

Summary of the TSCA Section 6(h) Restricted Bioaccumulative Substances

Substance Name	Applications	Hazards
PIP (3:1)	Adhesives Hydraulic fluids Resins Flame Retardants Lubricants Plasticizers	Toxic to aquatic plants, aquatic invertebrates, sediment invertebrates, and fish Potential for reproductive, neurological, and developmental effects Potential for effects on adrenals, liver, ovary, heart, and lungs
DecaBDE	Computers Televisions Circuit boards Cable insulation Upholstery fabric (automobiles, aircraft, Etc.) Mattresses Wood used in construction	Toxic to aquatic invertebrates, fish, and terrestrial invertebrates Potential for developmental, neurological, and immunological effects Developmental toxicity Liver effects Carcinogenicity
PCTP	Rubber	Toxic to protozoa, fish, terrestrial plants, and birds
2,4,6-TTBP	Fuel additive Lubricating grease Analytical standard Antioxidant in plastic and resins	Toxic to aquatic plants, aquatic invertebrates, and fish Potential for liver and developmental effects
HCBD	Plastic additives Protective coatings Analytical standards Chlorine recovery	Toxic to aquatic invertebrates, fish, and birds Possible human carcinogen Potential for renal, reproductive, and developmental effects

If you have concerns about bioacumulative substances POPs, TSCA 6(h), or any other regulations that might apply to your product − contact Enviropass for a free consultation!