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There has been a push in my home state of Connecticut to test more schools for PCBs. While no doubt well intentioned, this initiative is driven by two misguided assumptions:

1. That the presence of PCBs in schools pose a hazard to the building’s users; and
2. That if PCBs are discovered in a school it is a relatively simple matter to remove them.

The good news is that the first assumption is wrong, there is in fact no scientific evidence that PCBs in schools pose a hazard to the building’s users. The bad news is that the second assumption is also wrong, removing PCBs from a building is anything but simple; it can be an extremely difficult and expensive endeavor. Let me get into a little more depth on each of these questions.

Do PCBs in schools pose a health risk?
When you ask a toxicologist whether a chemical poses a health risk, the response you’re likely to hear is: “that depends on how much of the chemical someone is actually exposed to”, or to phrase it more succinctly, “that depends on the dose”. You see every chemical, even water, can be toxic (even deadly) under some conditions and in some doses. So answering the question of whether something is toxic requires an understanding of the exposure conditions and the dose. So let’s look at the conditions and PCB doses that a child is exposed to in a school situation.

Between 1950 and the early 1970s PCBs were used in a variety of building materials that might be found in schools including: caulk, paint, floor wax, adhesives (mastic) and surface coatings. PCBs were used in these products because they added durability and useful life to the products. The USEPA has determined that the most likely way for people to be exposed to PCBs in buildings is by inhalation. Although PCBs are not particularly volatile, small amounts do volatilize out of building materials over the course of years and decades.

These low concentrations of PCBs in air can be measured and the dose that a building occupant might be exposed to from inhaling them can be estimated. Based on this exposure mechanism the USEPA has developed PCB Public Health Levels that it considers to be safe for school children. The average daily PCB dose corresponding to EPA’s Public Health Level for an elementary school child is about 0.94 micrograms, a little less than one microgram per day.

To assess whether one microgram per day is a risky daily dose or not it’s helpful to compare it to the amount of PCB an elementary school child receives in their diet. You see PCBs are widely distributed in the environment and they are present in our food supply, particularly in animal products like meat and fish. Based on data developed as part of a recent market basket survey by the University of Texas, the average American elementary school child is exposed to about 4.6 micrograms of PCBs a day in their diet (much of this from hamburger and fish). That’s about 5 times more than they would receive by inhalation while attending a school with PCBs at USEPA’s Public Health Level.

So even if the concentration of PCBs in school air is four times USEPA’s public health level, it would still not equal the amount of PCBs an average elementary school child receives daily in their diet. For someone concerned about PCB exposures in schools the most effective place to make changes might be in the cafeteria menu and not in the building materials.

How hard and expensive can it be to remove PCBs from schools?
The simple answer is that removing PCBs from a building where they have been in place for over 30 years is really hard and very expensive. Here’s the problem: unless PCBs are in a laboratory sealed container, they tend not stay where they were put and over the years and decades they continue to move around. So a PCB containing caulk bead placed in the gap between a window frame and a brick or concrete wall will result in the PCBs migrating out of the caulk and into the abutting brick or concrete, with each passing year moving a little deeper into the brick or concrete. But that’s not all. The PCBs from the caulk bead also volatilize slowly into the air and then condense onto other building surfaces remote from the caulk bead. The PCB load on these remote surfaces slowly increases over time.

So removing PCBs from a school building involves more than just taking out the PCB source material, it also means identifying other materials in the building that may have become contaminated either directly or indirectly as a result of the PCB source. It often means deciding how to manage building structural components that have become contaminated with PCBs.

How do School Administrators Learn about PCBs in their Buildings?
How do school administrators learn about PCBs in their schools? Usually by surprise. Here’s how it often happens: The school district receives a grant for a window or sprinkler replacement project for an old school. The facilities department develops project plans and specifications and then lets out a contract for the work to the lowest qualified bidder. The work begins and continues until one day the facilities department hears from the contractor that PCBs have been discovered. The project grinds to a halt and the contractor recommends more testing.

The contractor’s first estimate for additional costs to manage the PCBs is high, but within the project’s budget reserve. However, as more test results become available and PCBs are found to be more wide spread than originally anticipated, cost estimates zoom past the reserve amount. This is when senior administrators or boards of education start asking questions, but by then the options for alternative action are limited.

TSCA – the Law of Unintended Consequences
You can read the Toxic Substances Control Act (TSCA) from cover to cover and you’ll find nothing about removing PCBs from schools or other buildings. Take a look at the 800+ page legislative history of TSCA and you will still find nothing about PCBs in schools. How about EPA’s PCB regulations (40 CFR 761)? No, still nothing about removing PCBs from schools or other buildings. So if there is nothing in the statute or the regulations about removing PCBs from schools or other buildings, and if there is no evidence that PCBs in building materials pose a health risk, then what explains the need to assess and remove PCBs from schools? Stay tuned for part 2.

Antelope Isle
Antelope Island (foreground), the causeway and Great Salt Lake. and the Wasatch Range on the mainland in the background.

This is my last post from my stay at the American Industrial Hygiene Association (AIHA) conference in Salt Lake City. But, it’s really not about the conference at all, it’s about Utah’s geology or at least the small pieces of it I was able to see. After arriving in the City on Saturday I had a great visit to the Natural History Museum.  By Sunday morning I was ready to get up close to some of Utah’s fascinating environmental settings. A quick internet search brought me to the Antelope Island State Park web site, which sounded like a very good destination for the day.

Antelope Island is the largest Island in the Great Salt Lake; it’s home to a large free ranging bison herd, pronghorn antelope, big horn sheep, mule deer and other wild animals and birds. From Salt Lake City it’s a little less than an hour’s to drive to the park entrance; the island is connected to the mainland by a 7-mile causeway that runs through the lake.

The Great Salt Lake, reputed to be the largest natural lake west of the Mississippi River, is actually a small remnant of historic Lake Bonneville. At its largest, about 15,000 years ago, Lake Bonneville covered 20,000 square miles and extended into Idaho to the north and Nevada to the west; it was almost as large as modern day Lake Michigan and was much deeper. Like the Great Salt Lake, Lake Bonneville was a Terminal Lake, meaning no rivers flowed out of it, but it captured all the runoff water from the surrounding mountains.

The limits of Great Salt Lake and the larger Lake Bonneville.

Geologists think that about 15,000 years ago the elevation of Lake Bonneville rose to the level of Red Rock Pass to the north in Idaho. Once the lake reached that level, its water began flowing down through the pass to the north. The erosion of the pass caused by the rapidly moving lake water led to a catastrophic flood that resulted in most of Lake Bonneville draining into Idaho’s Snake River drainage basin. The entire event is believed to have taken less than a year. Almost 5,000 cubic kilometers of water are estimated to have inundated southern Idaho as a result of the flood.

At over 6,000 feet elevation the mountains on Antelope Island would still have towered above the surface of ancient Lake Bonneville even at its height. While on the island I hiked to one of the recommended peaks and got fabulous views of the surrounding lake and mountains. While on my way I saw numerous bison, deer and antelope. The visitor’s center has excellent displays and helpful staff; it’s a good stop to make at the start of your visit. The only downside of my island adventure were the abundant no-see-ums, they were out in force and left my legs bitten and red.

Like most of the western US, northern Utah has experienced drought conditions for the past several years. As a result the Great Salt Lake has shrunk to a fraction of its size of only a few years ago. Walking out to the lake’s surface involves a longer walk over the salt crusted beach. As I was leaving Antelope Island I stopped to ask a couple of park rangers for a recommendation on where I should spend my last free morning on the day I would be leaving Salt Lake City. Almost in one voice they answered Snowbird, a town/ski resort at the top of a canyon just south of the city.


Jutting sharply up from the eastern side of the Great Salt Lake basin is the Wasatch Range, the western-most Mountains of the greater Rockies. Looking up at the mountains from the basin one sees deep “V” shaped canyons with peaks to an elevation of 12,000 feet. Not the highest in the Rockies, but they do have some of the largest unbroken elevation rises. Of the canyons, the Big and Little Cottonwood are some of the most studied geologic features in Utah. Snowbird, the name of a town and a ski resort, sits near the top of Little Cottonwood Canyon, with the Alta ski area at virtually the very top. The Cottonwood Canyons contain some of the most dramatic glacial scenery in the Wasatch Range.

These canyons, many of their tributaries and high-elevation basins were filled with hundreds of feet of glacial ice between 30,000 and 10,000 years ago. Geologists believe that The Little Cottonwood Canyon glacier reached beyond the mouth of the canyon and extended well into Lake Bonneville, calving ice bergs into the Ice Age Lake. In contrast, the Big Cottonwood Canyon glacier, is believed to have advanced only about 5 miles down its canyon, presumably due to less snow accumulation in the canyon’s catchment area.

After my morning brew at Alchemy Coffee I set off for Little Cottonwood Canyon. I knew my visit would be brief because my flight left in the mid-afternoon. The drive from the City to the mouth of the canyon was surprisingly quick. As I turned east up the canyon road I got that sense of being in a very special place. The canyon walls rise sharply on both sides of the road and the elevation kept ascending as the road went east deeper into the canyon.

Little Cottonwood Creek
My lunch time view of Little Cottonwood Creek.

The weather was perfect, another gorgeous Utah day, so the views were spectacular in all directions. When I got to Snowbird there was still snow on the mountains, but I was told that this was residual snow from a recent storm rather than the remains winter snow-pack, of which there had been little. I meandered up a steep trail for a bit, looked at my watch, sadly turned around and walked back to my car. On the way down the canyon I stopped beside Little Cottonwood Creek to have my lunch. An hour later I approached the SLC airport ready for the trip home.

Overall I was really taken by Salt Lake City, especially with how accessible it is to spectacular environmental settings. One is hard pressed to make it through the day without panoramic views of mountains and the Salt Lake basin, you really can feel the magic in the air. It is a great destination and I hope to be going back there real soon.

In my last post I discussed my invitation to speak about PCB exposures at the 2015 American Industrial Hygiene Association (AIHA) conference in Salt Lake City. In this post I want to review a fascinating remedial technology presented during the conference’s PCB session by Professor Cherie Yestrebsky from the University of Central Florida.

Zero Valent Metal PCB Treatment

Working with her graduate students, Dr. Yestrebsky developed a technology that effectively destroys PCBs on non-porous surfaces, such as metal sheet and pipes. The specific chemical reaction at the heart of her approach, sometimes referred to as “zero valent metal” chemistry, reduces PCB molecules by removing the chlorine atoms from the PCB molecules. Note that this technology has also been referred to as the “NASA method”.

In practice the technique involves the application of a specially prepared paste (containing a suspension of zero valent metal) to a PCB contaminated non-porous surface; the paste consists entirely of non-hazardous materials. Typically PCBs on non-porous surfaces are the result of their inclusion in the paint or other coating used on the surface. The paste softens the PCB containing coating and brings the PCBs into proximity with the zero valent metal. The chemical reaction between the metal and the PCBs is allowed to proceed for a period of time. The reaction takes place at room temperature, and no toxic gases or fumes are released during or after the reaction. The spent waste is not a listed or characteristically hazardous waste.

In addition to its effectiveness on non-porous surfaces, zero valent metal technology shows some promise for significantly reducing concentrations of PCBs absorbed into porous building materials like coated and non-coated concrete. When applied to non-coated concrete the mode of action is different because no surface coating is present. However, it appears that the paste is able to penetrate some distance into the concrete and destroy PCBs close to the surface. PCBs that have penetrated more deeply into the concrete matrix are not affected.

PCBs sorbed into concrete is an especially troublesome problem, particularly in occupied buildings like schools and residences. The technical solutions currently available to reduce or eliminate these PCBs are very limited and typically require the removal and replacement of the contaminated concrete. Removal of PCB contaminated concrete is usually expensive and often impossible without jeopardizing the structural integrity of the building.

Clearly the zero valent metal approach would be a welcomed addition to the PCB remediation tool kit for non-porous and porous surfaces. However, there looks to be an obstacle in the way of getting this technology into the remedial tool kit, namely the PCB regulations.

Do the PCB Regulations Stifle Innovative Remedial Solutions?

Subpart D of the PCB regulations describes in exhausting detail the permitted methods for PCB disposal. The language is so dense and the cross-references so convoluted that some have suggested EPA subcontracted the writing of Subpart D to the IRS, just joking. Subpart D does contain provisions that seem to create a regulatory path for the development of innovative PCB disposal methods.

However, the requirements for traversing this regulatory path are significant (read “abandon all hope ye who go this way”). I have heard presentations by USEPA scientists whose research into alternative PCB destruction methods came to an abrupt halt when they ran into the Subpart D regulations. If EPA’s own scientists can’t meet the Subpart D requirements, what chance does a non-federal government entity have?

Back to the zero valent metal technology. From the data I have seen the approach is 80% to 100% effective on non-porous surfaces and 40% to 80% effective on porous surfaces. On porous surfaces the effectiveness depends a lot on how deeply into the matrix the PCBs have migrated.

What standards do the PCB regulations require for alternative disposal technologies? Either equivalent to the PCB incinerator standards (aka 99.9999% effective – the “six-nine” standard) or possibly equivalent to a “high efficiency boiler” (aka 99.9% effective – the Herman Cain standard?). Of course an applicant wouldn’t know what would be acceptable until submitting an application to EPA, and you can’t submit an application until you have the data demonstrating that the technology meets the standard. Catch 22.

The Real Alternative Technology: Don’t Ask – Don’t Test

What it comes down to is this: EPA has set the bar so high for the introduction of an alternative remedial technology for PCB disposal/destruction that investing in the development of a potentially useful new technology is just too risky. Particularly in the case of PCBs in building materials a technology that provided significant concentration reduction (say greater than 50%) would seem to be very attractive even if it’s not 99.9% or 99.9999% effective. But the regulations do not permit that option.

And so the real alternative is often “don’t ask – don’t test”. Since there is no published data linking PCBs in building materials to adverse health effects, and since there are few practical approaches to removing PCBs from buildings, many have concluded it is better not to know if PCBs are present. They may just be right.


Last July I received an email from someone at the American Industrial Hygiene Association (AIHA) asking if I would be willing to speak about PCBs at their June, 2015 conference in Salt Lake City. Over the past few years the AIHA has been developing reference materials about PCBs for their members, and one of the focal points of the conference was to be PCBs in the built environment, particularly PCBs in building materials and air. After reviewing the information AIHA had already assembled and developing a topic for my presentation I agreed to submit an abstract.

The conference took place the first week of June this year at the Salt Lake City Conference Center where I was one of seven presenters speaking about PCBs. Over the next couple of posts I’ll highlight parts of the presentations that I found particularly interesting; I’ll also highlight some of my side trips in the Salt Lake City area.

PCBs in Building Air

Since the late 1990s researchers have known that PCBs from building materials can often be detected in indoor air. The concentrations detected are low (low nanograms to low micrograms of PCBs per cubic meter of air) and this reflects the relatively low volatility of PCBs. A lingering question that scientists pose is: are these airborne PCBs present in a gaseous or particulate form? In other words, are these PCBs stuck on to fine particles floating in the air like dust? Or are they present as free PCB molecules in air the same way oxygen and nitrogen are? At the conference several academic researchers presented data on this subject that was contrary to the information I’ve seen from others.

In short, these researchers found that the dominant PCB detected in air samples was a congener (an individual type of PCB molecule) referred to as PCB-28 (also known as 2, 4, 4’-trichlorobiphenyl) a PCB congener with three chlorine atoms. PCB-28 is a major constituent of the Aroclor mixtures 1016, 1242 and 1248. It is a much smaller part of Aroclor 1254 and is essentially absent from Aroclors 1260 and 1268. In the indoor air testing I am familiar with PCB-28 is detected, but not as a major component.

Also, in my experience the 4 and 5 chlorine containing PCBs tend to dominate air samples. I have attributed this to the parallel observation that Aroclor 1254 is the PCB mixture most frequently detected in building materials. Aroclor 1254 is a predominantly 5-chlorine atom mixture; it contains approximately 53% penta-chloro congeners. It is reasonable to expect that even when Aroclor 1254 is the mixture present in a building material, it would be the lower chlorinated congeners within the mixture that would be more likely to volatilize. However, as described at the conference, the extent of the shift towards lower chlorinated congeners in air coming from higher chlorinated PCB mixtures in building materials, is much greater than I have experienced in my own work.

While this may seem way too academic to worry about, from a risk assessment perspective it can make a difference, here’s why:

1. It could be that much of the higher chlorinated congeners being detected are actually associated with particulate matter and therefore may be less likely to be retained in the lungs;
2. If the PCBs are not retained in the lungs, then they do not contribute to a person’s PCB dose from breathing the air; and
3. Generally the lower chlorinated PCBs are considered to pose less risk than the higher chlorinated PCBs.

There are no answers for this yet, but I’ll continue to follow the issue.

Utah Natural History Museum

I had no plans when I arrived in Salt Lake City early on the Saturday afternoon before the conference started. It was a beautiful day, too early to go the hotel and why waste a beautiful day in a hotel room anyway? On the side of the street coming into the city was a billboard advertising the dinosaur exhibit at the Utah Natural History Museum. Since I still have more than a little of my boyhood fascination with dinosaurs, I decided going to the museum was the perfect way to spend the afternoon; good decision!

The museum is set in the foothills on the eastern side of the city in an attractive modern building with fabulous views of the surrounding mountains and the Great Salt Lake basin. The museum exhibits are laid out intelligently, the displays flowing easily into each other in a logical sequence. In addition to the incredible display of dinosaur fossils and reproductions, the museum is actively engaged in research and fossil restoration, a process that can be seen by visitors through laboratory windows.

The diversity of fossil types was beyond anything I have seen before or could even imagine. As much as I have enjoyed exhibits of ancient animals in east coast museums, they really can’t compete with what I saw at the UNHM.

If you have science-nerd children that love dinosaurs and there is any way you can swing it, my advice is to take them to Utah to see this museum. It was even better than I might have hoped, the exhibits were painstakingly constructed with great variety and well written descriptions. Personally, I was glad to be on my own so I could dawdle at my own slow pace and revisit favorite sections. A must see.


There was a recent news story about three local swimming pools being closed for the season because PCBs were discovered in the paint that lines the pools. Everyone involved acknowledges that the neither the paint nor the PCBs pose a health risk to users of the pools. However, once tested and found to contain PCBs, the paint must be taken out of service according to EPA’s PCB regulations. There is no requirement that the pool paint ever needed to be tested, but conducting the test commits the owner to a significant potential liability.

So it is the act of testing the paint and discovering the PCBs that triggered the need to remove the paint, which is likely to be a very expensive project, particularly if the PCBs are found to have migrated from the paint into the concrete of the pools. Again, no one is saying there is any health risk from the PCBs in the pool paint. So where did the idea of testing the paint come from? According to MassLive it was the recommendation of the City’s consultant, a large engineering firm engaged by the City to assist in developing repair options for the pools.

Since the use of PCBs in paint stopped between 35-40 years ago, the PCBs being discovered now have been in the pool for at least 35 years. By testing the paint for PCBs, the consultant has put the municipality in a position of spending an as yet unknown amount of money to remove the paint from the pools. Then there is the issue of what to do if the PCBs have migrated into the underlying concrete – something which they usually do. The ultimate cost of those seemingly simple PCB tests could well escalate to surprisingly high levels. Hopefully senior municipal representatives were advised in advance by their consultant of the potentials risks and costs of undertaking these PCB tests.

The Winter of 2015

For those of you from out of the New England area, you just can’t imagine how sick and tired we locals are of winter this year! My almost 89 year old dad told me this was without a doubt the snowiest, coldest winter of his life. And for once the worst of the weather has occurred along the coast, particularly in Boston. More typically Boston enjoys a temperate climate, with western and northern New England getting the brunt of winter’s snow and cold, but not this year.

In Boston and surrounding communities snow piles on street corners that are seven+ feet high are commonplace. Driving on smaller streets can be like driving through a snow tunnel. Here are a few typical scenes.

a lot of shovelingThis guy has a lot of shoveling to do – those mounds on the side of the road are buried cars!


where is my carHe’s just hoping to find his car.  Good luck!

fenway under snowEven famed Fenway Park is covered in snow. Pitching practice canceled.

For more details on this record breaking winter weather check this link:

Believe it or not, in comparing recorded annual snow falls this year is still in second place behind 1995-1996 (July 1, 1995 to June 30, 1996).  However, there is only a 5.5 inch difference left and we still have most of another month of winter to go!

Identifying the environmental liabilities embedded in real property is the goal of environmental site assessments. For obvious reasons, the purchaser (and their lender) would prefer to have this settled before any transaction takes place. With environmental remediation often coming at such a high price, ignorance of environmental liabilities can easily make the difference between a mutually beneficial deal and a financial disaster for one party. While these assessments typically evaluate contamination of soil and groundwater and the presence of leaking drums and underground tanks, they often ignore building materials that could contain polychlorinated biphenyls (also known as PCBs). Is this an oversight? And if it is, how serious is it?

Got PCBs?

PCBs were used in a wide variety of building materials prior to their ban in the 1970s. While this is hard for us to fully comprehend today, PCBs were one of the “miracle chemicals” of their day, as a result they were added to many, many products; this was the era of “better living through chemistry”.

The best known uses of PCBs in building materials were in caulk and paint, but PCBs are just as likely to be found in adhesives, floor finishes and concrete form release oils – to name a just a few applications. There aren’t any good statistics on this, but odds are that a building built before 1980 has a 50% chance of containing PCBs; whether its use is institutional, commercial or residential.

There’s only one way to know for sure whether a building has PCBs, and that’s to collect samples and test them. But there’s a big problem with this simple approach, testing a building for PCBs is opening Pandora’s Box; an innocent act that risks lots of unintended consequences. While there’s no requirement to test building materials for PCBs, this often well intentioned act can trigger a cascade of PCB liabilities. Testing building materials for PCBs is often compared to playing Russian roulette.

What’s the Downside?

Until the last decade, the question of PCBs in buildings was largely academic, but that’s changing fast as experience shows PCB remediation costs are too high to ignore. The change is due to USEPA’s shifting policy towards PCB enforcement.

When the first PCB regulations were issued in 1978-79, they contained a provision known as the “in-service rule” that permitted the continued use of existing PCBs in building materials; no new PCB building materials could be added, but the existing stock was grandfathered–in. But, when EPA rewrote the PCB regulations in 1998, they quietly eliminated the in-service rule. The result was that all the PCB caulk, paint and window glazing in hundreds of thousands of buildings was suddenly outlawed. This change was not made because EPA determined that PCBs in building materials were dangerous, in fact it was made for reasons completely unrelated to PCBs in buildings.

Although there is no requirement for testing, once an owner determines that a building contains PCBs the only lawful option is to remove them. But taking PCBs out of a building is no easy task; over decades PCBs slowly move out of the caulk or paint where they started and into abutting concrete, brick or wall board. Removing PCBs from these abutting materials has proven to be much more expensive than removing the caulk or paint itself.

On top of the direct PCB removal costs it would be wise to also consider  EPA’s extra-regulatory requirements, such as the confirmation of cleanup effectiveness through air testing; total project costs quickly become unpredictable. What might have started as an expensive but manageable $100,000 cleanup can readily grow to an unmanageable multimillion dollar cleanup, with no end to the costs in sight. Abandoning otherwise useful buildings can become the only option.

Location, Location, Location

As the old saying goes, when it comes to real estate,  nothing is more important than location; as it turns out this is true of the PCB regulations too. At least for now, EPA’s PCB enforcement program is not implemented consistently across the country. Program implementation is in the hands of the 10 EPA Regional Offices, and each of these sets its own priorities. So while PCBs in building materials are a hot topic with EPA in New England, they are rarely discussed in the Southeast (just one example).

What to do?

If you own or are responsible for a building that may contain PCBs, at some point you will need guidance on what your options are. If the only advice you are receiving is from people telling you that you need to test the materials, consider whether it’s time to find a new adviser. There are other alternatives besides testing. And even if testing is your best (or only) option, you should go into it with your eyes open, aware of the potential risks and possible strategies to reduce those risks.

There have been many recent press accounts regarding the discovery of PCBs (polychlorinated biphenyls) in certain building materials in Malibu California schools.  The Santa Monica-Malibu Unified School District (SMMUSD) retained Environ, an environmental firm, to serve as their consultant to evaluate the PCBs’ significance.  Environ tested indoor air samples, caulk samples and building material wipe samples for PCBs; based on the test results they developed an EPA approved plan for managing the PCBs in place.  But does this approach do enough to make the schools safe?

The Air Sampling Results

PCBs in school air are the primary health concern because all students and staff are breathing the air and would be exposed to PCBs if they were present.  Results of indoor air testing at the Malibu High School and at the Juan Cabrillo Elementary School show concentrations to be less than USEPA’s Public Health Values.  These levels are hundreds of time less than would be required to produce health effects.  Thus indoor air PCB concentration do not pose risk.

Wipe Sample Test Results

A secondary health concern is the potential for direct contact exposures to PCBs on walls, ceilings and other indoor school surfaces.  USEPA method wipe tests are used to evaluate surfaces for PCBs.  Wipe tests performed at the Malibu schools this summer found that PCBs were below USEPA’s concern level.  Thus, PCBs on building surfaces do not pose a risk.

Results of PCB Testing of Caulking

Caulking is the pliable material used to fill the narrow gaps between windows, walls and doors.  It is also used to fill joints between different construction materials like brick and concrete.  Ideally, caulk should remain soft and pliable for decades, but in practice this is hard to achieve.  When added to caulk, PCBs were terrific at helping caulk achieve these goals; until its use was banned.

Caulk is a building material often found with high PCB concentrations.  Some caulk samples from the Malibu schools do contain PCBs at greater than the USEPA limit, but this result has no bearing on health risk.  The positive air tests and wipe tests are relevant to health risk, the caulk tests are not.

Overall Evaluation of PCB Health Risk

Based on the test results for both Malibu schools, there does not appear to be cause for concern about adverse health effects from PCBs at the schools for either students or staff.

The Bigger PCB Issue

It’s well worth noting that no correlation has been found between the presence of PCBs in schools and adverse health effects in either students or staff.  This result is not surprising when you consider that the PCB exposure students and staff may receive is hundreds of times less than the amount required to cause a human health effect.

In fact, scientists have known for some time that risks from PCBs were seriously exaggerated as a result of a 1968 poisoning incident in Japan.  This incident, known as the Yusho rice oil poisoning, was thought to have been caused by PCBs and it received wide international attention.  It was not until many years later that Japanese scientists using better equipment discovered that the poisoning had not been caused by PCBs.  However, by then PCBs had been banned across much of the globe.

Almost every press article about PCBs includes these words in the opening line: either “cancer causing PCBs were discovered . . . ” or “probable cancer causing PCBs were discovered . . . “.  However, the scientific evidence (and there is quite a bit of this evidence) indicates that PCBs do not cause human cancer.  PCBs can cause liver cancer in rats, but rat liver physiology is different than human liver physiology.  Evidence of a link between PCBs and human liver cancer has not been found.

So while arguments about the risks from PCBs in schools are likely to continue, the science on human PCB toxicity is largely settled.  Remember that generations of students attended these same schools with these same PCBs for decades before anyone ever thought about it.  Everything points to these Americans being the healthiest and longest lived of any generation yet.

While the first alarms bells about PCBs in school buildings may have sounded in New England, the echo of that call-to-arms can now be heard on the west coast.   The discovery of PCBs in Malibu California schools and the press coverage that followed, have shattered the myth that PCBs in schools are only found in older east coast buildings.  For those following the Malibu PCB news, it’s hard to deny the drama that only southern California brings to a story; it’s not hard to imagine this  being the basis for a made for TV movie.

What are the facts?

According to a Fact Sheet dated July 27, 2014 by the Santa Monica-Malibu Unified School District (SMMUSD) an evaluation of school building environmental quality was started after three Malibu High School employees were diagnosed with thyroid cancer.  Following consultation with California environmental and health agencies, the district retained Environ, an environmental engineering firm to assess conditions in the Malibu High School and in the Juan Cabrillo Elementary School.

Environ’s evaluation included testing air, surfaces and certain building materials (paint and caulk) for PCBs.  Note that there is no known correlation between PCB exposure and human or animal thyroid cancer.  While PCBs were found throughout the schools, the detected concentrations were in most case well below USEPA regulatory and public health levels.  No air concentrations exceeded EPA recommended levels, although some caulk samples contained PCB concentrations greater than EPA’s 50 ppm regulatory criteria.

On August 14, 2014 the USEPA Region 9 Regional Administrator issued a letter in which he approved of the plans and actions taken by SMMUSD without exception.  The next day the SMMUSD issued a press release which informed the public that the district’s response to PCBs in the schools had won the endorsement of the USEPA.

What was the public reaction?

In 2013, after PCBs were found in the schools, an organization called Malibu Unites began seeking more testing and ultimately the removal of PCBs from the schools.  The group boasts a membership that includes “parents, teachers, community members, celebrity environmentalists, medical professionals, scientists, and environmental organizations working together for healthy, toxin-free schools”.   The presence of “celebrity environmentalists” has drawn a good deal of attention and press coverage to the group.

Here is an excerpt from an August 29, 2014 article published in the Los Angeles Register that helps convey the sense of frustration felt by the more concerned public:

“Unhappy with the school district’s current clean-up plan, Mayor Skylar Peak said he plans to demand further testing of toxic chemicals at the city’s public schools.

“The City of Malibu doesn’t have any control over its public schools because of state law, but council members decided to put the item on the next agenda after more than an hour of public comments from concerned parents during Monday’s City Council meeting.

“At least 24 parents have taken their children out of Malibu public schools because of elevated levels of PCBs – polychlorinated biphenyl – found in at least five classrooms at Malibu High School.  PCBs are found in window caulking, and sometimes the lighting, of structures built from the 1950s until the chemical was banned by the federal government in 1979.

“Parents and Peak want the district to test the source: the caulk.  The district says the classrooms are safe to re-enter.  Currently, the district is relying on “best practices” of cleaning, dust sampling and air sampling to identify PCB levels”.

Also, a notice of intent to sue the district and the EPA pursuant to the Toxic Substances Control Act was served by the Vititoe Law Group and the Public Employees for Environmental Responsibility (PEER) on August 20, 2014.   The notice gives SMMUSD 60 days to remove toxic materials from the schools or face a federal lawsuit.

Is Malibu the tipping point for PCBs in schools?

In his 2000 best-selling book “The Tipping Point”, Malcolm Gladwell explored the process by which some trends achieve great popularity, while others eventually fade.  The issue of PCBs in schools and other buildings has been simmering just below the surface of public awareness for several years, but outside of the small community of regulators, environmental lawyers and technical consultants, the full potential significance of PCBs in schools and other  buildings has not been understood.

For this post I am not offering my own analysis or opinion about the specific circumstances or health risks associated with PCBs in the Malibu schools.  What I am questioning is whether the Malibu PCB situation may draw sufficient public awareness that it becomes the tipping point that triggers an increased national awareness and policy development regarding PCBs in schools. We’ll see.

 At the end of May I posted an article that reviewed the routes of exposure by which people are exposed to PCBs.  After some general discussion, the article focused on the total PCB intake for three elementary school-aged child receptors who attended schools with different indoor air PCB concentrations:

  • A school with a relatively low 100 ng/m3 (nanograms per cubic meter) of PCBs in air;
  •  A second school with 300ng/m3 of PCBs in air (this is the EPA Public Health Level); and
  •  The third school with 400 ng/m3 of PCBs in air, 33% greater than the EPA Public Health Level.

The article calculated a total average daily dose of PCBs for these different student receptors by adding the amount of PCBs they ingested each day from food (this worked out to be 11.8 ug/day, aka micrograms per day), to the amount of PCB they inhaled at school and the amount they inhaled at home.  Recall that there are 1,000 ng in 1.0 ug.  Here is the summary table I ended up with:

Table 3 – Percentage of Daily PCB Exposure from Food and Air


% PCBs from Food

%PCBs from Air

Total % PCB Exposure

1 (100ng/m3)




2 (300ng/m3)




3 (400ng/m3)




The article’s conclusions were: 1) for these student receptors the overwhelming majority of their daily PCB dose comes from their diet; and 2) trying to reduce their daily PCB intake by reducing the concentration of PCBs in school air was a poor use of limited school resources because the proportion of the student’s daily PCB dose coming from air was too small to be of consequence.

What Happens When PCB Air Concentrations are even higher?

Let’s say you are growing a little skeptical about the potential health benefit of reducing PCBs in indoor air when the reduction is from 400 to 300 ng/m3.  But, what if the original indoor air PCB concentration is much higher than 400 ng/m3, what if it were 800ng/m3 (new Scenario 4) or 1,600 ng/m3 (new Scenario 5)?  Okay, take a look at Table 4:

Table 4 – Updated Sum of PCB Daily Exposures from Food and Air (in ug)





2 (300ng/m3)




3 (400ng/m3)




4 (800ng/m3)




5 (1,600ng/m3)




What I’ve done here is added the average daily dose of PCBs from food to the average daily dose of PCBs from air for our hypothetical elementary school students.  Scenarios 2 and 3 are the same as before, but new Scenarios 4 and 5 incorporate more extreme indoor air concentrations.  Scenario 5 is an unusually extreme indoor air concentration of PCBs.

Table 5 (below) uses the information just presented in Table 4 to identify what percentage of the student’s average daily PCB intake is coming from food and air with the new scenarios 4 and 5.

Table 5 – Percentage of Daily PCB Exposure from Food and Air


% PCBs from Food

%PCBs from Air

Total % PCB Exposure

2 (300ng/m3)




3 (400ng/m3)




4 (800ng/m3)




5 (1,600ng/m3)




Table 5 shows that even when elementary school indoor air concentrations reach 1,600 ng/m3, only 27% of an elementary school student’s daily dose of PCBs would be from air (mostly from school air, but some from air at home too).

The Upside of Removing PCBs from Schools

Finally, Table 6 identifies the percentage reduction in average daily student PCB intake that can be achieved by reducing the indoor air concentration to the EPA Public Health Level of 300 ng/m3:

Table 6 – Percent of PCB Exposure Reduction from Reducing Indoor Air Levels


% Reduction

2 (300ng/m3)


3 (400ng/m3)


4 (800ng/m3)


5 (1,600ng/m3)


A Lot of Pain to Reduce PCB Air Concentrations, but is there Real Gain?

A conclusion that I did not highlight in the earlier article is that bringing indoor air concentrations down from 400 ng/m3 (a level well above the EPA public Health Level) to 300 ng/m3 will reduce a student’s average daily PCB intake by roughly 2%.  From a toxicological standpoint a 2% reduction cannot be expected to have any discernible health benefit, in fact it is almost certainly a difference too small to measure using even advanced methods.

      By reducing an indoor air concentration from 800 ng/m3 to 300 ng/m3 the total dose reduction for an average student would be just under 10%, again this difference in total PCB dose is too small to measure in a student population if the study were to be done.  Just think about the quality control acceptance criteria for PCB analysis (generally results that fall between 70% and 140% of the true value are considered accurate).  It is unlikely that a 10% difference in dose could be reliably detected.

      For scenario 5, the case with 1,600 ng/m3 PCB in air, it is harder to dismiss a potential 21% reduction in PCB dose as inconsequential.  That large a reduction in dose could in-fact be significant from a health perspective if the total dose received were on the “steep portion” of the dose-response curve.  The steep portion of a dose-response curve is the dose range where small changes in dose are most likely to have the biggest effect.  However, in the case of PCBs the steep part of the dose-response curve just begins at doses between 50 to 500 times greater than the doses we have been considering.  In other words, reducing PCB air concentrations in schools, even those as high as 1,600 ng/m3, are unlikely to produce any measurable health benefit because:

  1. The PCB dose received from the average student diet is still much greater than the dose received from air; and
  2. The total average daily dose of PCBs received by average elementary school children is much less than dose needed to produce detectable health effects.