Persistent organic pollutants: toxic chemicals here to stay


The acronym POPs sounds harmless enough, bringing to mind glasses of bubbly champagne and harmless fireworks. The reality is far less celebratory.

Last week this column looked at dioxins, some of the deadliest pollutants we face, and members of a generally defined class of potent toxins called POPs. Just as “dioxin” has become a household word in Japan, so too will POPs. In fact, there are so many of these chemicals, known and unknown, permeating our environment, that Japan could soon be the industrialized world’s poster child for POPs.

POPs are persistent organic pollutants. They are called “persistent” because they are stable and do not break down quickly or easily; they have a carbon-based molecular structure, making them “organic”; and because they are very toxic they are called “pollutants.”

POPs also “bioaccumulate” — they are fat soluble and accumulate in living tissue. When tissue is consumed, the POPs pass on to the consumer, where they accumulate with other POPs that have been consumed.

A recent issue of Worldwatch magazine gives an example of how this bioaccumulation can take place in the food chain: Algae in lakes and rivers feed on dust containing PCB (a POP). Water fleas eat the algae, then are consumed by shrimp. Small fish eat the shrimp, then are eaten by trout. A woman eating a trout theoretically takes in all the PCBs that have been consumed by each animal all the way up the food chain. These PCBs can then pass to an infant through breast milk. (This does not mean mothers should avoid breast-feeding. Experts still believe that except in extreme cases, the benefits of breast milk outweigh the dangers of POPs.)

In short, though we sit proudly atop the food pyramid, we might more wisely view the pyramid as a giant inverted funnel, channeling POPs out of the environment and down our gullets.

PCBs (once commonly used as liquid insulators in hydraulics and transformers) are just one of the “Dirty Dozen” POPs that researcher Anne Platt McGinn mentions in her recent Worldwatch article (March/April 2000). The others are aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex and toxaphene (which are mainly insecticides), and dioxins and furans (byproducts created during incineration and organochlorine production).

These are just the top 12 nasties. “Many thousands of chemicals” could qualify as POPs, McGinn warns.

McGinn reports there are over 20 million synthetic chemicals now in existence, and “that number is increasing by more than 1 million a year.” That means, on average, somewhere in the world each day a new chemical is being synthesized every 27 seconds.

About 99.5 percent of these chemicals begin and end as “academic curiosities,” McGinn writes. Nevertheless, each year a substantial number gets beyond the lab. Exact figures are not available, but various observers estimate that about 75,000 synthetic chemicals are now in use worldwide. In addition, McGinn notes, “Every year another 1,000 or so new compounds enter the chemical economy, either as ingredients in finished products, or as ‘intermediates’ — chemicals used to make other chemicals.”

POPs are not due to tragic accidents or careless mistakes. As McGinn explains, they are produced as part of “ordinary industrial processes — plastic and pesticide manufacturing, leaky transformers, waste incineration, and so forth. POPs are an inevitable byproduct of business as usual. We are continually introducing new chemicals into the environment without any clear notion of what they will eventually do — or whether we may one day find ourselves in a desperate scramble to remove them.”

The variety, volume and toxicity of POPs are only part of the problem. As we blithely release tens of thousands of chemicals into our environment, we face a further threat from potential synergistic interactions among POPs and POPs that combine with other chemicals. “Multiple contamination is the rule, rather than the exception,” says McGinn, “but almost nothing is known about it.”

“What we do know,” McGinn warns, “is that most of the world’s living things are now steeping in a diffuse bath of POPs. No matter where you live, you’re likely to be contaminated by trace amounts of POPs.”

Here are a few of the product categories that depend on chemicals: plastics, resins, solvents, surfactants (used in detergents and other products), pesticides, pharmaceuticals, flavors, perfumes, dyes and pigments.

And that’s just a short list.

POPs are in our food, water, air, and, thanks to bioaccumulation, in all of us, and our kids. They are a chronic, toxic threat to present and future generations.

“If we want to reduce the risks from the vast and growing number of synthetic chemicals that are being released into the environment, we will have to rethink some of our basic notions of industrial development,” McGinn writes. “In its current form, the chemical sector is clearly at odds with our collective obligation to maintain human and environmental health.”

McGinn calls for fundamental reform beyond conventional regulation, and suggests that the chemical industry adopt some form of the Precautionary Principle. In McGinn’s words, “The principle states that when any action is contemplated that could affect the environment, those who advocate the action should show that the risks are either negligible, or that they are decisively outweighed by the benefits.”

Most importantly, this principle reverses the commonly accepted burden of proof in environmental controversies. At present, those who oppose an action must prove it is a threat to get it banned. As McGinn notes, the Precautionary Principle acts as “a kind of insurance policy against our own ignorance.” You want to pump a chemical into the environment? Fine. Just prove it’s safe first.

Industry, of course, stridently opposes such precaution, arguing that overemphasis on safety stifles innovation. So I propose a much simpler policy: Owners, managers, CEOs and policymakers (and their families) must live within 100 meters of the facilities they operate and regulate. If we make CEOs and policymakers our environmental canaries, precaution might just take root naturally.