- Review of new chemicals before they enter the stream of commerce, to determine whether they pose unreasonable risk.
- Whether a chemical poses unreasonable risks depends on balancing risks and benefits.
- Risk depends on both hazard and exposure; new uses that significantly increase exposure warrant the same scrutiny as new chemicals.
Making poisons and medicines using chemicals extracted from nature is an ancient art. But it was not until the nineteenth century that the science of chemistry developed. Modern chemicals have revolutionized and benefited society, but they still retain the ability to poison us. In fact, to a toxicologist, all chemicals are intrinsically hazardous—they all cause toxicity at a sufficiently high dose. Even water will drown us.
A chemical’s toxicity may be easy to recognize at high doses. More recently, we have learned that the same chemical can have much more subtle effects at lower doses. For example, lead can cause convulsions, coma, and death at high doses; this is old knowledge. But only in recent decades have we become aware that even low doses of lead in consumer products, such as paint or gasoline, can cause subtle effects on the brains of children. Some chemicals that cause acute reactions at high doses can, at low doses, trigger a mutation in the body that causes eventual cancer—an effect than may not become visible for decades. At least theoretically, a single molecule of some chemicals is enough to trigger such a mutation.
The development of tests to predict which chemicals can cause mutations or other toxic effects, as well as whether a chemical will persist in the environment, provide the scientific tools to help regulators minimize risk, and manufacturers to limit liability.
The Toxic Substances Control Act (TSCA)1 was enacted in 1976 to protect against unreasonable risk to health and the environment from chemicals. To accomplish this goal, TSCA provides for the evaluation and regulation of chemicals—both new and existing—by the EPA. TSCA is different from other acts we’ve studied so far, in that the substance regulated is a useful product, not a polluting waste. The act explicitly states that the EPA should exercise its authority in “such a manner as not to impede unduly or create unnecessary economic barriers to technological innovation,” while at the same time fulfilling the primary purpose of assuring that chemical innovation and commerce “do not present an unreasonable risk of injury to health or the environment.”2 This is an appropriate but tricky balancing act.
Who Is Regulated?
TSCA regulates the chemical industry. The lion’s share of requirements falls on those who introduce a chemical into the American market—namely, chemical manufacturers. That term is generally used to encompass importers of chemicals, since they perform the same function of placing chemicals in our midst.
The act also imposes certain requirements on chemical processors, distributors, commercial users, and disposers. In short, it touches the whole gamut of companies whose business involves—and who profit from—the proliferation of chemicals in our society.
What Chemicals Are Regulated?
TSCA covers all chemicals and chemical mixtures legally in commerce in the United States, with few exceptions.3 It reaches both new and existing chemicals. Particular attention is paid to chemicals produced in very large quantities—over one million pounds per year—because of the greater potential for exposure. There are three to four thousand of these, called high production volume (HPV) chemicals. Special attention is also paid to certain categories of chemicals known or suspected of being highly persistent or highly destructive, such as polychlorinated biphenyls (PCBs) and chlorofluorocarbons (CFCs). As science and technology advance, the EPA is challenged to address new developments such as biotechnology and nanotechnology products.
TSCA does not cover (nor does the TSCA inventory include) chemical substances subject to other federal statutes, such as pesticides, foods, drugs, cosmetics, tobacco, nuclear material, or munitions. Nor does TSCA apply to by-products with no commercial purpose. Further TSCA does not apply to chemicals manufactured only for research and development purposes—and therefore not really in the stream of commerce.
The EPA maintains a compilation of all chemicals currently in commerce in the US, called the TSCA Inventory.4 A substance on the list is, by definition, an existing chemical. There are over eighty-four thousand chemicals on the list, but the number constantly changes as the new chemicals are approved and added. The inventory includes information such as a chemical’s production (or import) volume and any restrictions on manufacture or use.
Any chemical not on the TSCA Inventory is, by definition, a new chemical.5 It is therefore subject to the notice and other requirements pertaining to new chemicals.
TSCA calls for the EPA to review new chemicals before they are manufactured and introduced into the stream of commerce. The EPA has established a New Chemicals Program (NCP)6 to perform this gatekeeping function. The major tools are notice, testing, and regulation. The act is intended to protect against unreasonable chemical risks before the new product reaches the market. And Congress articulates a policy that the development of adequate data concerning the effect of a chemical on health and the environment should be the responsibility of the manufacturer.7 But consistent with the coexisting policy not to hamper innovation, TSCA gives the EPA relatively limited regulatory authority.
TSCA gives the EPA authority to require testing and to impose restrictive regulations on new chemicals, but that authority is conditional. The EPA can require testing if it determines the substance may present an unreasonable risk of harm to health or the environment. The EPA can impose restrictions on sale only if it concludes from the tests that the substance presents or will present an unreasonable risk of harm. Both decisions require risk assessment.
Ninety days before a new chemical is manufactured and introduced into commerce, the manufacturer must submit a Premanufacture Notice (PMN)8 to the EPA. The PMN provides basic information about the chemical and projections for it, such as chemical identity, production volume, by-products, use, disposal practices, anticipated human exposure, and anticipated volume of environmental releases.
In addition, the manufacturer (or processor or distributor) must submit with the PMN any data on the health or environmental effects of the substance. But the manufacturer’s legal responsibility is less than you might expect. The manufacturer must submit any “known” or “reasonably ascertainable” studies. This would encompass published studies in the professional literature. If the manufacturer has access to private, unpublished studies, those are also required. But what about its own research on the potential risks posed by its new product? If the manufacturer has conducted any studies, those must be submitted. But the manufacturer is not required to conduct any tests or studies at this stage. There is no protocol or standard for any health or safety prescreening by the manufacturer.
The EPA has just ninety days to review the chemical and make a decision on whether testing or regulation are needed. If so, the EPA has some hurdles to jump. Absent any action from the EPA, the manufacturer is free to manufacture and sell the chemical after ninety days. The manufacturer then submits to the EPA a Notice of Commencement of Manufacture or Import (NOC). On receipt of the NOC, the EPA adds the chemical to the TSCA inventory, making it officially an existing (no longer new) chemical. The EPA receives between five hundred and a thousand NOCs each year.9
The EPA can require testing if it determines the substance may present an unreasonable risk of harm to health or the environment. Before a substance is thoroughly tested, how does the EPA decide if it may present unreasonable risk? Risk is a function of hazard, which is an intrinsic property of the chemical, plus exposure. A decision by the EPA to require testing can be triggered by either the severity of the hazard (hazard trigger) or by the level of exposure (exposure trigger), or both.10 The EPA assesses the potential risks of new chemicals, based on information in the PMN. This is essentially a triage process, looking for testing triggers.
Generally, the EPA looks for evidence a substance might cause such adverse effects as cancer, gene mutations, or birth defects. Evidence may come from the physical and chemical properties of a new substance. If a new chemical is structurally similar, for example, to a known carcinogen, that raises a red flag. Previous studies or anecdotal evidence may also raise red flags.
Under TSCA, testing is triggered if production, release, or the number of people exposed is substantial. The EPA has published numerical guidelines it uses to help determine if exposure is substantial enough to trigger testing. These guidelines are not binding on the EPA—it can rely on other evidence of exposure in individual cases. But under EPA guidelines, any of the following is enough to qualify as substantial for purposes of the exposure trigger:
- Production of 1 million pounds per year, or
- Release of 1 million pounds per year, or
- Human exposure of:
- 100,000 from the general population, or
- 10,000 consumers, or
- 1,000 workers
- 100,000 from the general population, or
Relation of Hazard and Exposure Triggers
There is a noteworthy distinction between hazard and exposure as triggers, based on a commonsense public health principle. No matter how much evidence of toxicity, hazard alone can’t trigger testing unless there is at least some evidence of exposure. By contrast, exposure alone justifies testing, regardless of hazard. Why does this make sense? Think about rattlesnakes, which are known to be highly toxic and can cause rapid death. They are not a concern in Alaska, because there are none; there is zero exposure and therefore zero risk. On the other hand, hazard is an intrinsic property of all chemicals, so the more people exposed, the more caution is indicated.
If the EPA determines, from its review of the PMN and any other information it can find, that the substance may present