We are continually exposed to a mélange of potentially toxic chemicals through the air we breathe, food and water we consume, and products that come in contact with our skin. Some of these chemicals are suspected of interfering with hormone function; causing cancer, asthma or other respiratory harm; damaging the brain and nervous system; and promoting reproductive disorders or negatively impacting developing embryos. More than 83,000 chemicals have been registered by the U.S. Environmental Protection Agency (EPA) under the Toxic Substances Control Act (TSCA) of 1976 for use in U.S. commerce. Most of these substances have not been thoroughly tested for their effects on human health. What's more, we are often exposed to chemicals in various multiple combinations that may produce unpredictable effects.

Some critics say the EPA fails to do enough to protect health and are pushing for reform of the 34-year old TSCA. In recent moves that suggest reform may be closer, the EPA in 2009 issued action plans for compounds that pose serious health or environmental concerns and announced as well the establishment of a "Chemicals of Concern" list. Furthermore, the Safe Chemicals Act of 2010, a bill that would strengthen TSCA, was introduced in Congress this past April; it may be taken up for consideration later this year.

In the meantime, seemingly harmless, ubiquitous products such as glue, weatherproofing sprays, household cleaners and gasoline additives have been causing illness in both workers and the general public for many decades. Paul Blanc, a physician who holds the endowed chair in Occupational and Environmental Medicine at the University of California, San Francisco, discusses the health risks associated with hazardous chemicals found in common consumer products. He is the author of How Everyday Products Make People Sick: Toxins at Home and in the Workplace (University of California Press, 2007), which addresses the following topics, along with many others, in more detail.

[An edited transcript of the interview follows. ]

How do everyday products make people sick?
There are two main issues: how people are exposed making everyday products, and how people are exposed using everyday products. But I think it is also important to remember an important third phase, which is what happens to these products after people are done using them and they are disposed of, recycled or put into the environment. The take-home lesson is that everything is connected to everything, and there is no magic wall that separates or protects consumers from hazards that are otherwise considered industrial hazards or the environment downstream. We have to think about things from cradle to grave.

How are these illnesses discovered? How do you link an exposure to a health outcome?
It gets progressively more difficult because, generally speaking, as you have lower levels of exposure stepping down from the industrial site to the home, and then from the home to the environment, it is more difficult (but not impossible) to make the connections. Often the connection between exposure and illness is made quite quickly and quite obviously early on in the life cycle of these materials. It is not simply that now we're clever enough to identify these things. If you look back in time you can see that often the lag time between the introduction of a new process or product and the recognition of a health risk was pretty rapid, within just a few years in many cases—even for sophisticated new materials. If it is an acute or fairly immediate effect following exposure, it is easier to identify the link.

One good example might be the ongoing hazards of some of the waterproofing spray components that have been on the market. These are sprays used by consumers to treat shoes or leather, or sometimes they are used in more specialty applications, like construction. In these products the common link is various kinds of fluoropolymers, and they cause very severe lung injury in exposed individuals, sometimes with fairly trivial home use of these products. That injury is manifest within 12 to 24 hours, and so it is apparent with greater ease that there has been an association between exposure and the illness.

Why are these exposures happening? Aren't there regulations in place to protect us?
Well for one thing there is not good premarket testing regulation. For certain materials, for example drugs and pharmaceuticals, there is premarket testing. But there is nothing like that for home consumer products. The stuff comes out on the market and the consumer or the occupational user is the guinea pig, the test animal.

Secondly, the main regulatory group that is responsible in this is something called the U.S. Consumer Products Safety Commission (CPSC), which to most consumers is an obscure regulatory body that has been extremely ineffectual. Their stated policy is to avoid almost at all costs mandatory recalls of products, and so most of what they do is work for voluntary recalls. There don't seem to be penalties associated, and I think the operative word here even in the best-case scenario is "recall," which means the material has already gone out to the marketplace.

What is the situation like in other countries?
The European Union (E.U.) has introduced a program called REACH (Registration, Evaluation and Authorization of Chemicals), which introduced premarket testing. It is not perfect, and there are some things that are exempted. I think that the key change that we'll need to introduce in the U.S. is more widely applied premarket testing. And in any event, American companies that want to sell in the E.U. are going to be forced to do this.

I think everyone has been aware of the issues with importation to the U.S. of materials that are contaminated. This was the most vividly shown in the lead-painted toy fiasco several years ago, in which literally millions of lead-contaminated toys were imported, primarily from China. Again this fell under the bailiwick of the CPSC, which came to a gentlemen's agreement with the Chinese to stop doing it. Of course what we have found more recently is that instead of lead-painted toys, we have cadmium-painted toys. Cadmium is another toxic metal—its toxicity is different than lead, but it is not something you want reintroduced in the environment, especially children's environments. By the same token, we have been exporting to China electronics for recycling, which has led to very high exposure levels for the Chinese that work in recycling of these materials. So it is a two-way street.

The U.S. has also posed international treaty restrictions on the exportation of hazardous materials. In fact, historically some of the things banned in the U.S. are only banned in their sale or use, not necessarily their manufacture or export. The actual banning of a product is a very rare and underused solution to problems that are otherwise probably insoluble. For asbestos, for example, probably the only true solution to the problem is a worldwide ban on asbestos. Although asbestos use is severely restricted in the U.S., in fact it is not banned. Worldwide, there is still a great deal of exportation. In that realm Canada is the main profiteer, since the asbestos mining occurs there; it has at every step of the way tried to oppose asbestos controls in terms of international trade.

Conversely, the U.S. has been considering the introduction of a manganese additive to gasoline. Environmental and occupational experts are very worried about this because manganese is a metal that is associated with Parkinson's disease, or Parkinsonian damage to the brain, and the idea of inhalable manganese being spewed out of every tail pipe in the country is a recapitulation of the leaded gasoline disaster of the 20th century. Ironically, the same company that made its profits from tetraethyl lead has come up with this manganese product, because the market for tetraethyl lead is quite diminished, as you might imagine. So far, the EPA (which regulates gasoline formulations in the U.S.) has been studying this and has held it up—it has not yet been approved. (This is an example of something for which there is premarket testing.) But in the meantime, Canada banned, or attempted to ban, the sale and use of this product. The U.S. sued them under the North American Free Trade Agreement and forced them to import it. Basically every nation, when it comes to its own economic interests, does not particularly care what happens elsewhere.

What kinds of illnesses result from exposures to household products?
A key thing is lung problems because we tend to be exposed to things through inhalation. There are products and materials people use in their homes that can, for example, cause asthma through sensitization. For example, the super glues that are so widely prevalent on the market contain various products that are known from the workplace to be capable of causing asthma, including urethanes and epoxides. Far more widespread is the exposure to chlorine gas from mixing household bleach with other products, because when you mix household bleach with an acid product it produces chlorine gas, and many of the household tile-cleaning products are acids of various kinds. I've already commented on the use of water-repellant sprays—household consumer-marketed products that you spray on upholstery or shoes—as another example of a product that can cause lung injury. All of these examples are lung-related, although some of these products could also cause skin sensitization and skin problems.

Issues that relate to other damage are usually more related to chronic, long-term exposure, and it is very difficult to show cause and effect, even in occupational groups. The challenge is that there needs to be many years of follow-up and large numbers of people being followed. The organomanganese gasoline additive MMT (methylcyclopentadienyl manganese tricarbonyl) is an example of a potential long-term risk to consumers through ubiquitous ambient air contamination. It would take years and years to show it [caused health effects], and by that time the damage would have been done. That's basically what we saw with tetraethyl lead—when we finally had the numbers and the time, we could show there was a decrement in IQ related to fairly low levels of lead, and most of that burden of lead exposure was related to leaded gasoline.

What do you think of so-called green chemicals and products claimed to be "benign by design"?
I would say, "caveat emptor." Sometimes it is very hard to separate out what may just be a marketing ploy from the real thing.

Beyond chemicals, what other factors are you concerned about?
Musculoskeletal issues are very large in the workplace, and the dividing line between what is a workplace and what is your home is not so clear anymore. The standard issues that affect white-collar office workers also affect people who do that kind of work at home, including keyboard and mouse work and the kind of hand and arm problems that may result. But it doesn't have to be purely white collar—some of the kinds of power and high-pressure equipment that in the old days would have been limited to construction workers and agricultural workers are now available to consumers. You can go to a home renovation warehouse store or hardware store and rent nail power guns and high-pressure paint spraying equipment, and these can actually cause physical trauma that can be quite important.

What steps can people take to protect themselves? What are some of the questions we should be asking about the safety of consumer products that we're using?
I think there are a few common sense things. One is that if something simpler will do, then use that. If you don't need to have a coffee cup mug handle re-glued in such a way that two trucks can't pull it apart, then why do that? Why not use a simple, old-fashioned Elmer's-type glue? If you can clean up something with soap and water, why do you need some tile cleaner that could interact with some other cleaner you're using? If you have access to industrial-strength products, don't take advantage of that unless you know what you're doing. Don't mix products unless you have studied the chemistry involved. I think hobbyists should put the same energy they put into their hobby into making sure that the way they're doing it is safe.