The Toxic Substances Control Act's Toxic Baddies

Here's the lowdown on the chemicals EPA says pose unreasonable risk and thus regulates under the Toxic Substances Control Act (TSCA).

TSCA gives the Environmental Protection Agency the authority to regulate the manufacture, use, distribution in commerce, and disposal of chemical substances. The regulations can range from labeling and testing requirements to specific restrictions on their production and use.

Of the some 80,000 chemicals manufactured and used in the United States, EPA has issued regulations to control just five "existing" and four "new" chemicals under TSCA's unreasonable risk authority [pdf]. (See EPA's explanations of what's meant by existing and new chemicals.) The identities of those nine chemicals: that was yesterday's topic. Today: we'll learn a little about each of them.


Workers drench the openings of an asbestos-tainted house in Arkansas  as part of a test of an alternative method to control asbestos. (EPA)

Asbestos, from the ancient Greek word for "inextinguishable," refers to a group of six naturally occurring minerals that have been used for thousands of years. Intact and undisturbed, asbestos poses no health risks. It's when asbestos fibers are released into the air, says EPA, that they "can cause serious health problems. If inhaled, these tiny fibers can impair normal lung functions, and increase the risk of developing lung cancer, mesothelioma, or asbestosis." (You know something's bad news when it has its own disease.)

Asbestos was first regulated in schools and in public and commercial buildings via the Asbestos Hazard Emergency Response Act added to Title II of TSCA by Congress in 1986. In 1989, EPA issued a more comprehensive ban on asbestos-containing products under TSCA's Section 6. However, in 1991 a federal court overturned most of these regulations -- ruling that EPA had not met the "unreasonable risk" threshold. As a result, TSCA's regulation of asbestos pertains only to "flooring felt, rollboard, and corrugated, commercial, or specialty paper" as well as new uses.

With more than 50 countries around the globe having banned asbestos, the failure of more comprehensive regulations on asbestos in the United States is often cited as an example of the inadequacies of TSCA (for example, see here [pdf] and here [pdf]). 

Polychlorinated Biphenyls (PCBs)

General Electric is dredging the Hudson River in upstate New York to try to remove PCB contamination in an effort to restore the river to a healthy state. (EPA)

PCBs were the only substances specifically identified for regulation by Congress when TSCA was enacted in 1976.

"[TSCA's] Section 6(e) prohibited the manufacture, processing, distribution in commerce, or use of PCBs other than in a totally enclosed manner after January 1, 1978, unless otherwise authorized by EPA rule."

PCBs have some nifty properties, like being able to
effectively lubricate at high temperatures. They also have some not-so-nifty
properties -- like being a persistent, bioaccumlative substance that EPA
categorizes as a probable human carcinogen and that's been shown to cause a
number of other serious, non-cancerous health effects in animals.
PCBs were used in manufacturing from the early part of the 20th century
until 1977 when they were effectively banned. For more on PCBs, check
out TheGreenGrok video below (and this short post I wrote to accompany it).


Hexavalent Chromium

Hexavalent chromium (of Erin Brockovich fame) is a known human carcinogen.

Chromium, a naturally occurring element in the Earth's crust, occurs in several forms: Trivalent chromium is an essential trace element whereas hexavalent chromium is toxic. Both forms are used in industries such as metal processing, tanneries, and stainless steel welding. 

An airways, skin and stomach irritant, hexavalent chromium is a known carcinogen. It may also be linked to negative developmental and reproductive effects. EPA's TSCA authority has been used very narrowly to restrict hexavalent chromium from being added as a water treatment chemical to control corrosion in commercial (not industrial) cooling systems and towers.

(Movie-goers may recognize that this is the chemical that Erin Brockovich, a legal clerk, fought in the early '90s. As the eponymous movie from 2000 chronicled, hexavalent chromium dissolved from cooling-tower wastewater at a Pacific Gas & Electric facility leached into the groundwater beneath the town of Hinkley, California. Ultimately, a class-action lawsuit spurred by Brockovich won $333 million in damages for the contamination.)

Dioxins (and Furans)

Dioxins carry a host of health hazards, from liver impairment to impaired immune and reproductive functions. (National Institutes of Health)

You might recall that early this year it wasn't E. coli plaguing Germany; it was dioxin.

Dioxins are primarily a byproduct of industrial processes such as smelting, paper production, and the manufacture of some herbicides and pesticides. They can also result from waste incineration and forest fires.

As I wrote in January, the health hazards of dioxin range from liver impairment and skin disorders to impaired immune systems, nervous systems, endocrine systems and reproductive functions.

Most regulation of dioxin is promulgated under the Clean Air Act and the Clean Water Act. In 1980 a rule was promulgated under TSCA to prevent the land disposal of dioxin from a chemical plant and to require prior EPA notification by any persons before disposing of dioxin-containing wastes. 

Fully Halogenated Chlorofluoralkanes

You might be old enough to remember that many aerosol products containing ozone-destroying fluorocarbon gases were phased out in the late 1970s. (

These compounds are anomalous on this list as they do not pose a direct heath threat. Their "unreasonable risk" arises from the fact that they act to deplete the stratospheric ozone layer.

In 1987 further regulations were imposed on these ozone-depleting substances through the Montreal Protocol (an international treaty), and since then, updates to the protocol as well as the Clean Air Act have led to more regulation and phaseouts. (For more on the ozone problem, see this post.)

The New Chemicals on the TSCA Chopping Block

Most accounts, it seems, delineate the chemicals listed above as the five toxic baddies that have been regulated under TSCA's unreasonable risk authority. However, as discussed yesterday, it's rarely noted that there are four other, so-called "new" chemicals also regulated by TSCA:

  • mixed mono and diamides of an organic acid,
  • triethanolamine salts of a substituted organic acid,
  • triethanolanime salt of tricarboxylic acid, and
  • tricarboxylic acid.

In the presence of nitrates or nitrosating compounds, these four compounds (all used in metalworking) pose an unreasonable risk of cancer. Because of this risk, TSCA was used to prohibit adding nitrates or nitrosating compounds [pdf] to metalworking fluids that contain these four compounds.


Lead-based paints were routinely used in homes built before 1978. Lead is a deadly chemical. (EPA)

Lead deserves some mention here, specifically lead-based paint, whose use remains a sad legacy -- even today its presence on the walls of homes, schools and offices poses a health threat, especially for children living in old and often economically depressed homes. Lead has been linked to a range of health effects "from behavioral problems and learning disabilities, to seizures and death."

The manufacture and use of lead-based paint was banned for residential use by the Consumer  Product Safety Commission in 1978. However, TSCA also regulates work practices and the disposal of lead-based paints from renovation, repair and painting. And so some might argue it too should appear in this list of chemicals regulated by TSCA. (For more, see also here.)

So there you have it -- the TSCA bad guys. The other 80,000 plus chemicals out there? Well ... they're out there.

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