Over the past year there have been a number of articles published about reproductive risks to orcas (killer whales) posed by PCBs (example articles 1, 2, and 3).  Some of these articles go so far as to claim that orcas are threatened with extinction due to their reproduction being inhibited by PCBs.

But do PCBs really pose really pose an extinction risk to orcas?  Or have these authors used limited information to draw conclusions that are out of proportion with the actual science?  With this post I want to consider what we know about orcas and PCBs and evaluate whether the warnings in these recent articles are realistic.

orcas photo


Orca Characteristics and Behavior

Orcas are among the top predators in the ocean.  They are not true whales, instead they are the largest member of the dolphin family.  Although all orcas belong to the same species, scientists that study them group them into three subpopulations (resident, transient and offshore) based on their behavior.  As you would guess, resident orcas live in near-shore locations and remain there for their entire lives, they eat either fish or other marine mammals.

The transient orcas remain close to shore, but migrate along the coast in the pursuit of prey, which consists of mostly of other marine mammals.  Offshore orcas are the least well known, but they live and feed far from shore and are believed to feed on sharks and other large fish or marine mammals.  Although all three groups belong to the same species, they do not interbreed or otherwise mix socially despite being considered highly social within their own group.  As a species, orcas are generally not considered endangered.

Almost everything we know about orcas comes from studies of resident populations because they are relatively easy to monitor.  Possibly the most carefully studied orca group (known as the Southern Resident Killer Whales), lives in the waters of the Pacific Northwest, off the coast of Washington state and southern British Columbia.  Two other closely monitored resident orca groups are: a pod residing off the west coast of Scotland (known as the West Coast Community); and the Northern Resident group, which lives off the more northerly coast of British Columbia.

Orca Population Decline

While the (North American) Southern Resident and (Scottish) West Coast Community groups are different in many ways, both are now experiencing population decline.  In the case of the Southern Resident group, which now has 75 individuals, scientists concluded the decline is due to the reduction in their nearly exclusive food source, Chinook salmon.  Scientists have found a close link between orcas’ annual reproductive success and the abundance of Chinook salmon in their home waters.  A recent decline in the salmon population is believed to have resulted in the orcas expending more effort to achieve an adequate diet and having less reproductive success.  These scientists are hopeful that the key to increasing the Southern Resident group’s population is changing the salmon fishery management to ensure the orcas receive adequate nutrition.

In contrast, the West Coast Community orca group off of Scotland may indeed be on the path to extinction.  This group consists of four-females and four-males, a total of 8 individuals, with no new births in the group in 25 years.  In fact, the group was recently reduced when an older female died after becoming entangled in fishing lines.  Scientists speculate that the remaining females may now be too old to give birth.  There is no agreed upon cause for the reproductive failure of the West Coast Community orcas, however, speculation has whirled around the idea that PCBs may have caused a lack of fertility among the females as a result of its ability to mimic estrogen.

PCBs and Orcas

One report that sheds considerable light on the question of PCBs and orca reproduction is a 2000 Institute of Ocean Studies article, which describes a study in which scientists collected fat samples from 47 live, wild orcas off the coast of British Columbia and tested these samples for PCBs, furans and dioxins.  The samples were collected from transient orcas as well as individuals form the Southern and Northern Resident Groups (note that the Northern Resident Group is distinct from the Southern Resident orcas, but there is some overlap of their territories of the coast of British Columbia).  This study is among the most comprehensive investigations of PCBs in orcas.

The study had three important findings relative to orca reproduction:

  1. The study found all of the orcas sampled had surprisingly high concentrations of PCBs in their fatty tissue. The transient and Northern Resident orcas had higher PCB concentrations than the Southern Residents.  This is believed to be attributable to their different diets.  Transient and Northern Residents consume primarily marine mammals and Southern Residents consume primarily salmon.  Salmon has significantly lower PCB concentrations than do the marine mammals preyed on by the orcas.
  2. In each of the three populations the adult males had significantly higher PCB concentrations (and presumably higher PCB body burdens) than did the adult females. Since their diet and thus their potential PCB exposures are the same, the only explanation for this is that the adult females transfer their PCB body burden to their young during gestation and after birth through their milk when nursing.  Because the fat content of orca milk is high, and because this fat carries the PCBs accumulated by the mother, these PCBs are transferred to the nursing young.  It is estimated that 60% of the mother orca’s PCB body burden is transferred to their young by nursing.  The transfer of PCBs from mothers to their young is seen in other mammals as well.
  3. The concentrations of dioxins, furans and dioxin-like PCBs in the orca fat samples were less than anticipated based on the relatively high concentration of non-dioxin like PCBs. The authors suggest that this finding may explain how the orcas could tolerate such high PCB body burdens, without experiencing adverse effects such as reproductive failure.  The authors speculate that the more toxic dioxins, furans and PCBs may have been metabolized by other animals lower on the food chain such that only the less toxic and more chemically stable PCBs are actually passed on to the orcas in their food.


The objective of this post was to consider whether the available scientific evidence supports the claim that PCBs may drive orcas to extinction as a result of reproductive failure.  It is undeniably true that orcas carry high PCB body burdens, and that these PCBs are the result of their diet, whether that diet consists of fish or marine mammals.  However, based on the 2000 Institute of Ocean Studies report, it does not appear that high PCB body burdens are contributing to reproductive failure in the populations studied.

As odd as it may seem, some of the strongest evidence for orca reproductive success from this study is the much lower PCB concentrations found in the adult females compared to those detected in the adult males.  Since the PCB exposure of the females and males are similar (they all derive PCBs from their diet), the consistent large differences in concentration in their fat tissue can only be explained by the transfer of the adult female’s PCBs to their young.   Sexually immature females and males have similar PCB concentrations.  But, upon reaching reproductive age, the female’s PCB concentrations drop, while the male’s PCB concentration continues to increase with age.

The study data indicates that the orcas continue to reproduce successfully among the transient and the resident orca populations on the North American west coast despite their high PCB body burdens.  In other words, the PCBs do not appear to be adversely impacting the orca’s reproduction.

It may not be appropriate to extrapolate the results of the North American orca/PCB study to the decline of Scotland’s West Coast Community group.  However, the study clearly does not provide support for the contention that PCBs are causing a worldwide decline in orca population.

PCB or Non-PCB

The other day I got an email asking a good, basic question about the federal PCB regulations: “Where did the 50 ppm regulatory cut-off for PCBs come from?”  Is it a science based number? Or did the 50 ppm number just get pulled out of the air?

The more I thought about it, the more consequential the question seemed.  Thus a new PCB blog post seemed to be in order.  As you’ll read, the 50 ppm level wasn’t exactly science based, but then it wasn’t totally pulled out of the air either.

What does TSCA say?

Congress passed and the president signed the Toxic Substances Control Act (TSCA) in 1976.  This statute directed EPA to develop two sets of PCB regulations that became known as: (1) the 1978 PCB Disposal and Marking Rule; and (2) the 1979 PCB Ban Rule.  TSCA does not specify a PCB concentration cut-off limit to let EPA (or the rest of us) know exactly what Congress had in mind as to how concentrated PCBs had to be for them to fall into the regulatory net.

Wise legislators must have agreed that setting a regulatory cut-off limit is a decision best left to the professional staff at the regulatory agency. (I will leave the question of whether the phrase “wise legislators” is an oxymoron for a more politically oriented blog).  So TSCA is silent on the issue of PCB cut-off concentrations.  This was something EPA needed to figure out.

What does EPA say about the 50 ppm cutoff?

In the draft public comment version of what became the Disposal and Marking Rule, EPA proposed a 500 ppm cut-off limit for the regulation of PCBs.  But, by the time the final rule was published in the Federal Register (February, 1978), EPA was already getting cold-feet about this high a limit.  The agency warned in the preamble to the Rule that they would likely soon reduce the cut-off level to something in the neighborhood of 50 ppm, but needed to go through a more prolonged regulation development process before they did so.  Quoting from the preamble:

“The Agency is aware that adverse health and environmental effects can result from exposure to PCB’s (sic) at levels lower than 500 ppm; however, at this time the Agency is not establishing a level based on health effects or environmental contamination but rather a level at which regulated disposal of most PCB’s can be implemented as soon as possible”.

EPA goes on to explain that they had only recently acquired the additional scientific information needed to support a lower cut-off level, and that this information was not available in time to include in the administrative record or hearings for the Disposal and Marking Rule.  More from the Rule’s preamble:

“As a consequence, the 500 ppm definition for a PCB mixture, as proposed, is included in this final rule making.  However, the Agency plans to propose a lower concentration of PCB’s, possibly in the range of 50 ppm or below, to define PCB mixture in the forthcoming . . . regulations”.

In accordance with EPA’s warning, the preamble to the May, 1979 PCB Ban Rule explains that EPA had in fact decided to adopt the 50 ppm cut-off level.  This was after the Agency considered cut-off levels of 1 ppm, 10 ppm, 50 ppm and 500 ppm.  EPA concluded that reducing the cut-off level to 10 ppm was impractical because it would bring far too much physical material and too many unrelated chemical processes into the PCB regulatory net.  EPA pointed out that a 1 ppm cut-off level would obviously be even more impractical than the 10 ppm level.

So the 50 ppm level was chosen as the happy medium.  It was a concentration that could be “administered” by EPA (presumably unlike the lower 10 ppm and 1 ppm levels) and yet would capture hundreds of thousands of pounds of PCBs that would have gone unregulated with a 500 ppm cut-off level.

So, that is the story of where the 50 ppm PCB cut-off concentration came from.  It wasn’t rocket science, one could argue it was barely science at all.  In retrospect it was a compromise between those interested in controlling as much PCB as possible and those whose focus was on what could realistically be accomplished.

Now some might wonder why it is that under the 1998 PCB Mega Rule there is a 1 ppm cut-off concentration for PCB remediation waste, but that’s a question for another blog post.

caulk and bricj

PCBs, polychlorinated biphenyls, are a group of related chemicals that were used for a variety of applications up until the 1970s.  In the 1960s the development of improved gas chromatography methods allowed environmental scientists to become aware of the environmental persistence and global distribution of PCBs in the environment.  Since that time there have been hundreds of studies conducted to better understand the environmental transport and fate of PCBs.

However, it has been only over the past 20 years or so that studies have focused on learning more about PCBs that were incorporated into building products and their fate in the indoor environment.  Much of what has been learned is surprising and counter-intuitive.

For example, while it is generally true that PCBs have low volatility and low water solubility, it turns out that even at room temperature they are volatile enough to permit them to migrate in and around buildings at concentrations high enough to have regulatory implications.  This migration may take place slowly, over the course of several decades, but in some instances, it has happened in as little as a year.  With today’s sensitive instrumentation, chemists are able to track the movements of even tiny concentrations of PCBs as they migrate.

This post is a primer on the three primary categories of building materials which contain PCBs and how their PCBs can move inside of buildings.

Primary Sources

As the name suggests, primary sources are building materials that were either deliberately or accidentally manufactured with PCBs as an ingredient prior to their installation in a building.  The most common primary sources are:

  • Caulking;
  • Paint;
  • Mastics;
  • Various surface coatings; and
  • Fluorescent light ballasts (FLBs).

FLBs are different from the other materials on this list because they use PCBs in an “enclosed” manner.  This is defined as use in a manner that will ensure no exposure of human beings or the environment to PCBs.   However, with continuous use FLBs are known to deteriorate, sometimes resulting in the release of PCBs.  Only FLBs manufactured before the PCB ban (1979) should contain PCBs and by now (2017) any of these older PCB containing FLBs should have been replaced with non-PCB ballasts since even the youngest PCB FLBs are almost 40-years old.  FLBs are considered to have had a functional life span of only 10-15 years.  The type of PCBs used in US-made FLBs were almost exclusively Aroclors 1242 and 1016.

The other primary PCB sources on the above list are considered to be “open” PCB uses because, unlike FLBs, the PCBs were not contained in an enclosure.  In most of these cases PCBs were added to the materials to improve the performance of the products by contributing: fire resistance, plasticity, adhesiveness, extended useful life and other desirable properties.  For PCBs to impart these properties they were generally included at concentrations ranging from 2% to about 25%; this is equivalent to 20,000 parts per million (ppm) to 250,000 ppm.  The most common PCBs found in US-made building materials are Aroclor 1254 followed by Aroclor 1248, 1260 and 1262.

PCBs can sometimes be present in primary sources by accident rather than by design.  The presence of Aroclor PCBs in primary sources at concentrations less than 1,000 ppm (equal to 0.1%), or non-Aroclor PCBs at any concentration, may indicate an accidental PCB use.

Under the federal PCB regulations primary sources of are referred to as PCB Bulk Products and they are regulated when their PCB concentration is 50 ppm or greater.

Secondary Sinks and Secondary Sources

When a PCB primary source is in direct contact with a porous building material, the PCBs in the primary source can often migrate from the primary source into the porous material.   Porous building materials known to adsorb PCBs in this way include concrete, brick and wood.  When this migration occurs, the now PCB containing porous materials are referred to as secondary PCB sinks.  Secondary sinks often have PCB concentrations in the range of 10-1,000 ppm.

While the federal regulations apply to primary sources when their concentration is 50 ppm or greater, requirements for secondary sinks are stricter.  They are categorized as PCB Remediation Wastes and are regulated when their PCB concentration is 1 ppm or greater.

In some situations, the PCBs in secondary sinks can be remobilized and either migrate directly into other porous materials or they can volatilize into the air.  When this occurs, these secondary sinks may be referred to as secondary sources.  In practice one hears the terms secondary sinks and secondary sources being used interchangeably.

Tertiary Sinks and Sources

Tertiary sinks arise when PCBs from primary or secondary sources volatilize into the air and then condense onto other materials in a building.  The significance of volatilization as a PCB migration pathway was underappreciated until recent times because the relatively low volatility of PCBs suggested that the volatilization rate was too low to be meaningful.  However, laboratory testing and numerous real-world examples have demonstrated that volatilization of PCBs from primary and secondary sources with redeposition on other materials can be significant in some settings.   Tertiary sinks often have PCB concentrations between 1-100 ppm.

Some authors prefer to use the term secondary sinks to describe both secondary and tertiary sinks.  Personally, I prefer to use ‘tertiary sinks’ to identify materials affected by indirect contact (through the air) and ‘secondary sinks’ to identify materials affected by direct contact to primary sources.  However, I acknowledge that it is not always evident whether a material is a secondary or tertiary sink.

Why Understanding PCB Sources and Sinks Matters

Understanding the ways that PCBs move around in buildings is important if your goal is to reduce potential exposures inside of buildings.  It is a frequent occurrence in PCB building remediation for primary sources to be removed only to find that indoor air concentrations have not been reduced to the extent expected.  Or for air concentrations to fall immediately after remediation, only to return to previous levels with the passage of time.  This is often due to an insufficient appreciation for the influence and action of secondary and tertiary sinks.

If you have a particular PCB in building condition that needs a fresh set of eyes to review it, consider reaching out us for another opinion.

Soxhlet Extraction Schematic
Soxhlet Extraction Schematic

Thanks to a friend’s sharp eye, I recently learned something new about the analysis PCB caulk samples.  Because of its potential significance I thought it deserved a special blog note.

First a little background on how caulk samples get tested for PCBs.  It’s basically a three step process:

  1. First a carefully measured amount of the caulk sample is extracted with an organic solvent. As a chemist would say, PCBs would rather be dissolved in a non-polar organic solvent than to be in the caulk, so they move from the caulk to the solvent.  If you are in USEPA Region 1 this extraction must be conducted using “the Soxhlet method” also known as EPA Method 3540C.  The Soxhlet method is the gold standard of extraction methods, but it uses a lot of energy, water, solvent and glassware so ecologically it is not a very “green” method.  Additionally, it takes a long time.  The method calls for the extraction to proceed for 16 to 24 hours. In other EPA Regions other extraction methods (such as sonication) may still be acceptable.
  2. Once the PCBs have been extracted from the caulk to the solvent phase, the solvent needs to be cleared of the other potentially interfering chemical schmutz that got extracted out of the caulk along with the PCBs. These cleanup steps are fairly critical before you run any of the extract through the gas chromatograph (GC).  The GC is the instrument that will tell the analyst how much PCB is in the extract.
  3. Following the cleanup steps you inject a very small portion of solvent extract  into the GC. At the end of the GC is a very, very sensitive detector that can measure the truly minuscule amounts of PCBs in that may have been in the sample.  The detector generates a signal that allows the analyst to back-out the concentration of PCBs that were originally in the caulk, if any.

Well this probably seems simple enough, but think for a minute about what might happen when your GC is set to measure PCB concentration levels of between 1 and 10 ppm and all of a sudden a caulk sample comes through with 200,000 ppm of Aroclor 1260! Yikes!  This is the equivalent of trying to weigh a full grown African elephant on an office postage scale!  You are not going to get an accurate weight, and your postage scale will never be the same.

And of course it’s not a happy day for the analyst who will now need to spend many hours or days getting the residual PCBs out of that very sensitive GC detector, not to mention all the grossly contaminated glassware and other lab equipment.  Obviously labs need to take steps to protect themselves from this possibility or they would very quickly be out of business.

How Labs try to Reduce this Risk

One thing labs can do to reduce the risk of blowing out their GCs is to ask the people submitting samples if they know the approximate concentration of PCBs in the caulk.  But usually they don’t know, and if it were your lab would you necessarily take the word of the person submitting the sample?  I’m not sure I would.

Another option is to pre-screen samples using a “quick and dirty” method to get a rough idea of the PCB concentration.  Such a method might involve a very simple extraction, followed by a big dilution of the extract to reduce the PCB concentration (if any are actually there) followed by injection into the GC.  Something very close to this procedure is known to EPA as Method 3580A, but is also known colloquially as the “swish and shoot” method.

Now this method is completely fine for getting a quick read on the relative PCB concentration in a sample.  In fact, if the results from the swish and shoot screening shows the analyst that the sample is hot (i.e. lots of PCBs well in excess of the regulatory limits) then there really is no need to conduct any further analysis because the person submitting the sample is in most cases just wanting to know whether the concentration is greater or less than the regulatory thresholds for PCBs.  So some labs stop the analysis at this point and report the results from the sample prepared with the method 3580A extraction.

Situations Where Swish and Shoot Results might Steer you Wrong

If a sample is analyzed following a relatively inefficient extraction and the resulting sample concentration still exceeds regulatory standards, then a more efficient extraction can only result in a concentration that exceeds standards by an even greater amount.  As long as the sole analytical objective is to identify whether or not samples exceed regulatory standards, then this objective can be satisfied by a less efficient extraction provided the result is greater than the regulatory standard.

However, if your analytical objective is also to map PCB concentrations over an site area to achieve a clearer picture of how concentrations change spatially in the field, then you need an extraction and analysis protocol that is consistent, efficient and reproducible.   Without these qualities you won’t be able to reliably tease out the forensic trends you want from the data.

The lesson to be learned  from choosing  the right extraction method for PCB analysis is the timeless quality assurance principle of identifying how you want to use data before you collect samples and analyze them.  Some of the biggest problems with scientific studies can arise when data is collected for one purpose, but then used in a way that was not anticipated by the scientists who collected and analyzed the samples.  Data that satisfied the original study’s objectives may not be suitable for a subsequent study with different objectives.

So-called “meta studies” and a number of retrospective studies where batches of pre-existing data are aggregated to increase the statistical power of a study’s conclusions can be guilty of not thinking about whether the data quality objectives of the original studies meet the needs of the new study.  What motivates the meta study authors is creating as large a data set as possible to give their results statistical significance.  But this quest for large data sets can cause the consideration of data quality objectives to fall by the wayside.

These “big data” studies can sometimes make for splashy headlines because the large number of samples make results look statistically significant.  But too often these results need to be walked-back because the authors did not adequately consider the data quality objectives of the original studies in assembling their meta-data sets.

Last Word

So to reiterate again, think about how your PCB data will be used before you submit the samples to a lab, then make sure the extraction and analysis methods to be used will give you the data you need.

In Part 1 of this post, I wrote about the misguided push in my home state of Connecticut to test more schools for PCBs. There’s a misconception that PCBs, even with the low potential doses likely to occur in the indoor environment, pose a health risk. This misconception persists despite a 50+ year history of PCBs in many school buildings without a documented instance of a student, teacher or other staff member experiencing adverse health effects indicative of PCB toxicity. And yes, scientists have looked.

While the presence of PCBs in buildings does not seem to have caused bodily harm, the act of removing them from school buildings can be devastating to school and municipal budgets. Experience shows that removing PCBs from schools is a very expensive process; one whose budget can grow exponentially as more information and test data becomes available. There are relatively few communities whose annual school budgets can withstand the impact of a school PCB removal project.

I ended Part 1 with this paragraph:

“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?”

The goal of Part 2 is to answer that question.


In the beginning . . .
From their first publication in 1978/79 until the 1998 Mega-Rule changes, the PCB regulations contained what I call the “in-service rule”, which reads in part:

“NOTE: This subpart does not require removal of PCBs and PCB Items from service and disposal earlier than would normally be the case. However, when PCBs and PCB Items are removed from service and disposed of, disposal must be undertaken in accordance with these regulations. PCBs (including soils and debris) and PCB Items which have been placed in a disposal site are considered to be ‘‘in service’’ for purposes of the applicability of this subpart”.

My naive interpretation of the in-service rule is that PCBs that were already incorporated into some product – and thus in-service – could remain in service until that product was taken out of service.  Thus PCBs in building materials could remain in those materials (and those materials could remain where they were) until they were removed from service and prepared for disposal.

(First Disclosure: In a conversation with EPA headquarters, I was told the in-service rule was only intended to apply to PCBs that had already been disposed of in a manner that did not comply with the PCB regulations. However, I think it’s obvious from the use of the words “in-service” that this current EPA HQ interpretation is inconsistent with a plain reading of the text. In my view it takes a somewhat “strained” interpretation to equate the terms “in-service” with “illegally disposed of”).

Looking beyond the in-service rule, even a casual examination of the current PCB regulations makes it apparent that EPA’s main regulatory focus has been on liquid PCBs, like the ones found in transformers and capacitors. This makes sense when your objective is to limit the further spread of PCBs to the environment – liquids are prone to being spilled and obviously spread much more easily than solids. Objectively, the regulation of PCBs formulated into solid products, like building materials, seems to have been an afterthought for EPA. While its researchers knew about PCBs in building materials, even in the 1970s, EPA’s regulation writers either did not know about them or just decided they weren’t important.

The 1994 proposed use authorization
EPA’s regulation writers finally started paying attention to PCBs in solids in the mid-1990s.  In a prelude to the 1998 PCB Mega-Rule, EPA published an Advance Notice of Proposed Rule Making (an ANPRM) in 1991 requesting comments on a number of issues concerning PCB regulation. In the December 6, 1994 Federal Register, EPA published a summary of the comments received and explained how the agency planned to respond to them.

Many commenters described experiences where PCBs had been unexpectedly discovered in building materials (such as caulk, paint and adhesives) during demolition or renovation projects. These commenters told EPA that removing these PCBs posed a huge engineering, construction and financial burden. EPA responded that it had previously been unaware of this problem, but was now proposing a solution to this unintended consequence of the PCB regulations. A few pages later, in the very same 1994 Federal Register volume, EPA proposed a new use authorization, 40 CFR 761.30(q), to legally authorize the continuing use of PCBs incorporated into solid building materials.

In the preamble to the proposed change EPA explained its rationale for the new use authorization this way:

“While the continued use of unauthorized pre-TSCA materials is a violation of the existing PCB regulations, in most cases the premature removal of the media containing PCBs could only be achieved with great difficulty and at enormous expense given the extraordinary efforts that would be required to remove the PCBs.” (Emphasis added).

So as of December 1994, the stage was set for the adoption of a new use authorization for PCBs in solid building materials. But, as one of my old bosses liked to say, “There’s been many a slip between the cup and the lip”. When, four years later, EPA finally promulgated the 1998 PCB Mega-Rule the proposed use authorization for PCBs in building materials was missing. What happened? The only explanation on offer was found at the end of the 1998 Mega-Rule preamble:

“Finally, EPA is deferring regulatory action on proposed 761.30(q) for future rule-making”. . . . “Although EPA received many comments supporting the proposed authorizations, many commenters wanted EPA to drop many, if not all, of the proposed authorizations. EPA needed additional time to review the recently submitted risk assessment studies and also to obtain additional data for certain uses in order to reduce the uncertainties associated with the available studies.”

Since it is almost 20 years later, do you think it would it be impolite to ask whether these uncertainties still exist? In a conversation with EPA headquarters a few months ago I was told not to expect a use authorization for PCBs in building materials any time soon.

So what exactly are the uncertainties EPA is concerned about? And how do they relate to PCBs in schools?

(Second disclosure: This the end of the historical account. The rest of this post is based on my research and opinions).

We know a lot about PCBs. In fact they are among the best studied of all the man-made environmental contaminants. There are 209 different individual PCB chemicals, known as congeners that make up the PCB group; we know all their molecular weights, volatilities, and many of their other physical properties. We divide them into dioxin-like and non-dioxin like categories based on the way they interact with biological receptors, which has also been studied in depth. There are elaborate risk assessment models that claim to assess the level of risk based on just which particular combination of the 209 congeners are present. Every week there is a new research paper published about PCBs with even more information.

What is probably more important is that we know the average concentration of PCBs in the environment and in people has been dropping significantly since the 1970s. We know that the average daily and annual doses of PCBs people receive has also declined significantly. And of course we know that despite their significant efforts, scientists have not been able to tease out any consistent evidence of adverse health effects in people exposed to PCBs in building materials.  Remember, consistent reproducible results is the most important factor separating good science from bad science.

The question I set out to answer with this post was: 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?

Because, after all if Congress were inclined to pass legislation, or if the EPA were going to promulgate regulations that would cost communities and public school systems billions of dollars, don’t you think there would be a cost-benefit analysis somewhere? Before new federal regulations come into being, there is supposed to be a rigorous assessment of potential negative and positive impacts – for the very purpose of avoiding costly unintended consequences. So um, what happened here?  Because there never was a cost/benefit analysis; there never was an honest discussion with the public about risks, costs and potential benefits about regulations that could collectively cost communities hundreds of billions of dollars.

Reluctantly, the conclusion I’ve come to is that there are no good answers to my questions.  My best guess is that most EPA researchers and independent scientists would rather not be the ones to point out that the emperor has no clothes; but the facts are that the fear of PCBs in buildings is without scientific foundation. But at the cost of millions of dollars per building incurred to our school budgets unnecessarily, isn’t it time to to pay attention to the real science?

Final thoughts
Last July EPA issued new guidance for schools and other buildings that may contain PCBs. While the preface contains disclaimers that the new guidance is not intended to replace the requirements of the PCB regulations or TSCA, after reading them one could be forgiven for thinking that this was pretty much what they were supposed to do. The guidance recommends a sensible Best Management Practices (BMP) approach to managing known or suspected PCBs in buildings and downplays the need or desirability of testing building materials for PCBs.

It’s unlikely that this new guidance will be codified into regulations any time soon, but it is helpful for EPA to soften its guidance and it hopefully signals a more rational approach to the issue of PCBs in buildings going forward.


Postscript: OTO just changed its web host, which led to some confusion in the posting of this article.  We apologize for any inconvenience.

cons 1

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.

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.

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.