By Elizabeth Grossman
While commercially manufactured polychlorinated biphenyls (PCBs) were banned by the US Environmental Protection Agency (EPA) in 1979 due to concern about their extreme environmental persistence and toxicity – including potential to cause cancer – current EPA regulations allow the presence of limited amounts of PCBs that occur as manufacturing by-products. These by-product PCBs are not created or added to products intentionally but occur as a result of certain manufacturing processes, among them the synthesis of certain pigments that go into dyes, inks and paints.
As I reported earlier this month in Environmental Health Perspectives (EHP), recent research has found these by-product PCBs, particularly one known as PCB-11, in air and water samples all across the United States as well as in Great Lakes sediment. These PCBs have also been identified in commercial paints and in printed products – papers and plastics and dyed textiles used in clothing – colored with pigments known to be associated with by-product PCBs. Japan’s Dyestuff and Industrial Chemicals Association has recently detected PCBs in the majority of organic pigments it tested. These by-product PCBs have also been detected in effluent discharged from facilities recycling paper printed with inks that contain these pigments.
So the question arises, are people who work with such pigments – either in their production or in the manufacture or disposal of products that contain them (dyes, inks, paints and colored products such as printed papers, plastics and textiles) – being exposed to these PCBs? And if so, does this exposure pose a health risk?
Legacy and non-legacy sources of PCBs
PCBs, which are entirely synthetic and don’t occur naturally, are a complicated class of chemicals. There are 209 different PCB molecules or congeners, each named for the number of chlorine atoms it contains. The PCBs that have received the most attention are the commercial mixtures that were used as insulation fluids in transformers and electrical equipment among other industrial and commercial applications; a number of these PCBs have been identified as carcinogenic.
The commercial PCB mixtures are well-recognized as environmental and health hazards both short and long-term. Their adverse health effects include liver damage, adverse impacts on the immune, endocrine, nervous and reproductive systems – and cancer. But recently, environmental health scientists and medical researchers have begun to identify a range of health effects associated with PCB congeners not previously studied, including endocrine disrupting and neurological effects that can occur at very low levels of exposure.
We’ve known for decades that the old now-banned (or “legacy”) commercial PCB mixtures can last for an extremely long time once released into the environment. That PCBs can occur in the production of certain pigments – particularly diarylide and azo pigments that primarily make yellows but also some reds and orange colors, and phthalocyanine pigments that make up certain blues and greens – is also well and long-known. These by-product PCBs apparently occur in syntheses that involve chlorine, hydrocarbon compounds and salts processed at high temperatures.
The EPA knew and accommodated this in its 1979 regulation of PCBs with a rule that was finalized in 1982. But in 2010 EPA issued an advance notice of proposed rulemaking indicating it would consider tighter regulation of these by-product PCBs. EPA has proposed dropping the current 50 part per million (ppm) limit for by-product PCBs to 1 ppm. The comment period for this proposed rulemaking closed in August 2010 but EPA is not expected to conclude this process until 2014. The FDA, meanwhile, allows PCBs up to 10 ppm in food-packaging paper while EPA’s water quality limits for PCBs is 170 parts per quadrillion (ppq). And while the FDA allows PCBs up to 2 ppm in fish and 3 ppm in poultry, the Spokane Tribe has set its PCB fish consumption level at 3.37 ppq.
Until recently, the assumption was that PCBs being detected in the environment were all coming from these legacy sources. But PCBs are continuing to be generated and are present in a wide variety of products. Relatively new and increasingly sensitive monitoring and analytic technology, has enabled researchers to identify a greater range of PCB congeners and at smaller levels of detection, including the by-product PCBs, which have a distinctly different profile from those in the old commercial mixtures.
But where in manufacturing processes – either of pigments, paints, inks, dyes and colored products – might workers be exposed to these PCBs? And can these processes be altered so that PCBs do not occur? The answer to both these questions is at this point, we really don’t know.
The pigment and dye industry trade associations stated in written responses to EPA’s advance rulemaking notice that if the EPA were to prohibit or deeply reduce allowed manufacturing by-product PCBs, their industries would be in jeopardy. While researching my story for EHP, I contacted numerous ink, pigment and dye companies to ask about the difficulty of changing manufacturing processes or materials to avoid the creation of by-product PCBs. None of the many companies in the industry I contacted was willing to discuss the issue of by-product PCBs in any detail.
What I was able to learn is that the supply chain for pigmented products – inks, dyes and paints and the finished colored products – is complex and typically involves proprietary information, not only for the colors themselves but for the formulations that enable the colors to work in specific applications – in specific printing processes or with specific materials, for example. Many pigments and dyes are now manufactured in Asia and imported elsewhere for incorporation into other colorants and manufactured products – so this trail is often long and difficult to follow. And given the pigment and dye industry’s long and well-known history of using toxic materials and generating toxic waste, it is not surprising that hazardous by-products are part of the process.
Worker exposure limits
When it comes to worker protections, the Occupational Safety and Health Administration (OSHA) currently only has Permissible Exposure Limits (PELs) for two now-banned commercial PCB mixtures: one known as chlorodiphenyl (42% chlorine) for which the OSHA PEL is 1 milligram per cubic meter of air (mg/m3), and another for chlorodiphenyl (54% chlorine), for which OSHA’s PEL is 0.5 mg/m3. The National Institute for Occupational Safety and Health (NIOSH) PELs for these compounds, however, are 0.001 mg/m3. These standards apply to airborne PCBs and PCB-laden dust. Because PCBs can be absorbed through the skin as well as inhaled, extensive personal protective equipment is recommended. But the sources of PCBs identified in relation to these occupational health guidelines typically involve remediation and other handling of equipment and materials contaminated with legacy PCBs – including fluorescent lamp ballasts and old caulk. By-product PCBs are not discussed in existing workplace regulations.
OSHA’s PCB safety and health guideline says that current “Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new information is available.” So it would seem there is research to be done. If by-product PCBs are turning up in paper, plastic and textiles printed with dyes and inks that contain pigments in which these PCBs occur, more testing of such pigmented products to determine the presence of such PCBs seems in order. Similarly, testing of workplaces where such pigments and their colored products are used and manufactured would seem to be called for to determine if PCBs are present in ways that could expose workers or others using these materials. Finally, the hardest question to answer will be: Do such exposure pose human health hazards?
We know that detection or presence of a hazardous chemical does not necessarily mean it will cause someone harm. But we also know that these contaminants are but one of many that people are exposed to constantly. And we also know that health effects associated with these PCBs are among those now implicated in common chronic health disorders. So more research is needed, specifically into the health effects of the by-product PCBs. Another question to answer is how PCB environmental and exposure limits can be met if PCBs are allowed to be present in products that far exceed those levels.
Elizabeth Grossman is the author of Chasing Molecules: Poisonous Products, Human Health, and the Promise of Green Chemistry, High Tech Trash: Digital Devices, Hidden Toxics, and Human Health, and other books. Her work has appeared in a variety of publications including Scientific American, Salon, The Washington Post, The Nation, Mother Jones, Grist, and the Huffington Post. Chasing Molecules was chosen by Booklist as one of the Top 10 Science & Technology Books of 2009 and won a 2010 Gold Nautilus Award for investigative journalism.