PCBs: back with a vengence?

Teaching college-aged students can keep you young or, make you feel really old. In this case I was feeling particularly old. My college advisor, with whom I’d kept in touch over the years, had invited me to talk about chemical contaminants with her class of soon-to-be graduating seniors. Wanting to distinguish between the “trendy” chemical contaminants, and the “legacy” contaminants, I brought up PCBs.

“You all know what PCBs are don’t you?” I’d asked, after observing what seemed like puzzled expressions on more than a few young faces. Shrugs all around, with the exception of one eager and confidently raised hand.

"Polychlorinated biphenyls,” responded the proud owner of that hand.

The rest were still clearly puzzled. As was I. How could these bright young students be ignorant of one of this century’s most important legacy chemicals? Not only that, but how could these students who attended college in Schenectady, home of General Electric – the company that not only brought “Good Things to Life,” but also introduced PCBs to much of the Hudson River - be ignorant of one of the most important contaminants in their backyards? (Well, aside from depleted uranium, but that’s another story.)

PCBs, I realized, define the chemical generation gap. These kids didn’t have a clue. Except for all the flap over the Hudson River cleanup nearly a decade ago unless you're unfortunate enough to be directly impacted by Monsanto (one of the primary producers of PCBS), GE or other PCBs users, you rarely hear about the chemical these days.

Until this past weekend, that is. I should have known something was up when a friend and colleague working at Berkshire Community College sent a Facebook message indicating she had some questions about PCBs. She never followed up, and to be honest, I thought, “What could anyone want to know about those these days?” Never mind that the college is located in Pittsfield, MA – the other home of GE – where the company not only contaminated the nearby Housatonic River, but also neighborhoods all over the city (again – a story for another time.)

But PCBs reentered my life, and many others, on a sunny Sunday morning, with a front page article about PCBs in caulking published by the Boston Globe. Over the past couple of years, PCBs have been discovered in samples of window and masonry caulking of school buildings and others built circa 1960-70 and possibly earlier. Most of it found following incidental or voluntary testing including voluntary testing by Berkshire Community College. At some sites, testing revealed incredibly high concentrations - meaning hundreds of thousands of parts per million. Which means hundreds of parts per thousand. That’s high, when disposal of waste containing just fifty part-per-million PCBs often requires special consideration. I immediately wondered about my kid's school - though recently renovated, the original building had that 60's look. As a new member of the school committee and more than well aware of our dire finances did I even want to know about this? As a parent with two kids in the school, and a toxicologist - I am obligated to ask.

PCBs are really a complex mixture of similarly structured chemicals – carbon rings with assorted number and placement of chlorines. Which means when considering PCB toxicity, one must consider toxicity of many different chemicals which may act independently or as a complex mixture. That is, exposure to one PCB may influence the toxicity of another PCB, or one kind of PCB might affect the brain, while another may affect reproduction. Understanding health and environmental impacts of single chemicals is difficult enough. Understanding complex mixtures can take a lifetime -- and plenty of good scientists have devoted their careers to PCBs (they just don't make Science News or the front page these days.)

To date, PCBs are considered all-around toxicants at least in laboratory studies (and by association, in epidemiological studies on highly exposed human populations) affecting reproduction, neurological development, immune response and reproduction and are considered a probable human carcinogen by the USEPA. In the environment in addition to impacting other species, they are credited with wiping out mink populations that once lived along contaminated rivers. Mink for example, are exquisitely sensitive to the reproductive impacts of certain kinds of PCBs.

But before there is widespread panic, there are questions that must be answered, including 1) concentrations of PCBs in caulking 2) amounts of PCBs released from contaminated caulking 3) how might one be exposed to PCBs from caulking, 4) and potential exposures of teachers and students exposed PCBs released from caulking? (According to the Globe this is the topic of an ongoing study.)

Now that PCBs are back on the front page, maybe the next time I ask students about these important legacies, they won’t be so puzzled.

UPDATE: EPA recently issued a press release (on Sept 25 2009) along with the following website for those concerned about PCBs in caulk: http://www.epa.gov/pcbsincaulk/