CAMBRIDGE, Mass.—In the basement workshop of Rockler Woodworking and Hardware, instructor Palo Coleman is wrapping up a class on epoxy resin art, a popular craft for creating sparkly jewelry or charcuterie boards and “river” tables, with vibrant glass-like features that seemingly flow through the wood surfaces.
As Coleman’s students—a woodworking hobbyist, and a retired builder and his doctor daughter—gather around a workbench, he tears pieces of 400 grit sandpaper and demonstrates how to sand and stain the elm and cherry coasters they crafted and adorned the week prior with electric blue, red, and copper epoxy resins. The students had mixed two substances—a resin and a curing agent—added pigments, and poured the concoction into grooves. The chemicals reacted to form the solid plastic now glittering on the coasters’ surface.
While beautiful, these resin materials are loaded with a dangerous hormone-disrupting, and likely carcinogenic, chemical called bisphenol-A diglycidyl ether, or BADGE. BADGE is similar to bisphenol A (BPA), an endocrine disruptor that can hijack the body's hormone functions at tiny concentrations. BPA is linked to multiple health problems including cancer, diabetes, reproductive impacts, and behavioral problems, and is especially harmful to unborn and young children whose hormone systems are still in development.
BADGE is far less studied than BPA, but its chemical structure concerns researchers because it includes reactive compounds known to cause cancer and other serious diseases. It is broadly used beyond artisan woodworking, such as in glues, boat repair and refinishing, in powdered coatings in automotive and other metal finishing, and in can linings. Zero workplace exposure limits on BADGE leave the door open for potentially harmful worker exposures, and sketchy, or even false, advertising about the safety of woodworking and art supplies. Researchers worry that the failure to adequately test and regulate BADGE leaves scores of workers, artisans, and individuals at risk.
“Joe woodworker, who knows nothing about chemistry, is being given products that are endocrine disruptors of massive significance, potential carcinogens, and told to go play with them,” Terrence Collins, Teresa Heinz Professor of Green Chemistry at Carnegie Mellon University, told EHN.
BPA’s “insidious alter ego”
BADGE is the most widely used epoxy resin.
Wooden coasters embellished with epoxy resin art.
BADGE is the most widely used epoxy resin, with an annual U.S. production of several million tons. EHN’s review of epoxy resin kits sold online and in stores found just nine of 16 brands provided material safety data sheets (MSDS). Out of these, all but one, which blacked out its chemical ingredients, reported their resins contained BADGE at concentrations as high as 70% to 100%. Many resins also contain nonylphenol, another endocrine disruptor.
Collins began investigating BADGE a decade ago after learning that BPA was used in epoxy resins. Reviewing BADGE’s chemical structure, he thought “this compound is too dangerous to be used,” he said.
BADGE is a BPA molecule with two reactive chemical groups stuck to it that link to other bisphenol molecules to yield a viscous epoxy polymer. Mixing it with an acid, or heating it, in the presence of a solvent, sets a reaction in motion that ends in a chain of alternating BADGE and bisphenol molecules (BPA, BPS, or PBF) that form a tough plastic.
It has a so-called “double alkylation structure,” which means it can crosslink with DNA and potentially result in cancer, said Collins. In 1989, the International Agency for Research on Cancer (IARC) found limited evidence for the carcinogenicity of BADGE. Two of five mice studies reviewed by the IARC found increases in epidermal, kidney, and lymphoreticular/haematopoietic tumors following skin application of BADGE. The other studies saw no increase or were “inadequate for evaluation.” IARC also noted that glycidaldehyde, a metabolite of BADGE, is carcinogenic to experimental animals and classified as possibly carcinogenic to humans.
BADGE “really should be treated as a potential carcinogen,” Frederick vom Saal, BPA expert and distinguished professor emeritus of biological sciences at the University of Missouri, told EHN. “It’s not rocket science, that’s just applying the chemistry to the biology.”
BADGE has been identified as an endocrine disruptor in animal studies, and shown to promote the differentiation of fat cells in humans. A recent review of research to date—noting little information available at human-relevant levels—concluded that BADGE is a potential endocrine disruptor.
BADGE differs from BPA in that its reactive chemical groups make it an unstable compound that can break down into byproducts that aren’t well known or studied.
It’s like “BPA’s insidious alter ego,” Patricia Hunt, Meyer distinguished professor in the School of Molecular Biosciences at Washington State University, told EHN. “It disappears, or turns into something else, and we don't know what the metabolites are.”
BADGE’s half-life in the body isn’t known, but evidence suggests it can linger for a long time in the blood, said Collins, and if it's traveling around in the body, it can make its way into cells where it does its damage.
One of the few studies on human exposure found widespread prevalence of BADGE, Bisphenol F diglycidyl ether, and five BADGE metabolites in blood and fat samples collected from New York City residents. The same study also measured BPA levels and found that they positively correlated with BADGE and its metabolites.
“If there’s BADGE, there’s BPA,” said vom Saal, confirming these findings on co-exposure. Resin can linings for food are still predominantly made with BADGE, he said, and they all release BPA at varying amounts.
Lack of regulations and worker exposure
Despite these warning signs, there are no regulations for workplace exposure to BADGE, and the Food and Drug Administration continues to allow both BADGE and BPA use in can linings, arguing that exposure levels are low and that the chemical clears the body rapidly when ingested. An FDA spokesperson pointed EHN to its policy on approving food contact materials and said the agency “ is not aware of any new information that has raised concern about the safety of BADGE under its intended use.”
The Consumer Product Safety Commission, which has the authority to develop standards for art materials, declined to comment on whether the agency was addressing BADGE in epoxy resins, but directed EHN to a guide on health hazards in art supplies.
When BPA is breathed in or absorbed through the skin, however, Hunt said her research shows it gets into the blood and lingers. And that’s how woodworkers would be exposed—through skin contact when mixing and pouring the resin materials, or by breathing in dust when sanding the cured plastics.
“As you sand … you're probably getting a nice coating on your body, some of which is making its way into your body” even if you’re using a vacuum system on the wood dust, said Hunt.
Fully cured resins in theory would not release BADGE when sanded, at least in the short-term, but “very few reactions are ever 100 percent complete,” said Collins. That residual BADGE could become airborne on dust during finishing.
In woodworking “everything is carcinogenic”
“In woodworking, the assumption is that everything's carcinogenic."
Rockler Woodworking epoxy aisle.
Coleman, a vegan with closely-cropped grey hair and pale blue eyes, is knowledgeable about woodworking’s chemical hazards, although he did not know that the resin mixes contained a potential carcinogen and endocrine disruptor.
“In woodworking, the assumption is that everything's carcinogenic,” he told EHN. “That's why it's just best to use best practices whenever working with any chemical.”
Best practices for Coleman, who has taught at Rockler for five years, means mixing resins outside in open air when possible, not mixing large portions at once, wearing personal protection equipment, and waiting at least a week for the materials to cure before he sands.
In class he donned purple nitrile gloves and safety glasses when handling the resins, and showcased Rockler’s HEPA air filtration system on its routers, sanders, and saws.
“I train people how to use epoxy and how creative it is,” said Coleman. “When they leave, it's on them to do the things that keep them safe that they've learned in the class.”
Other woodworkers may or may not be aware of woodworking hazards. Steve Minnehan, a 35-year-old woodworker perusing the epoxy resin aisle at Rockler, questioned whether epoxies were any more dangerous than other chemicals he’s exposed to. “I know it’s incredibly harmful. I mean, this has a cancer warning,” he said, waving his hand at a product on the shelf. “It’s the nature of the work.”
Inadequate warning labels
Michaels craft store resin aisle. A few products warn of potential cancer and reproductive harms.
Blick Art sells the Art Resin brand, one of a handful that market their products as BPA-free. ArtResin is 80% to 90% BADGE.
What of the occasional hobbyist? The Internet is a free-for-all of DIY art resin videos, and most don’t talk about safety.
“They never tell you on YouTube that [uncured] epoxy will harden in your lungs, because it hasn't cured yet. All these people who sand it the next day, if they're not wearing hazmat suits, it's really dangerous,” said Coleman, pointing to a wood piece with a deep vein of resin that had yet to cure from the week before because it hadn’t been mixed properly. As an experienced woodworker, Coleman can tell when resin is completely cured, but that may not be the case for people doing projects at home.
Worsening matters, the majority of epoxy resin kits sold in stores and online—in bottles up to half a gallon in size—are poorly labeled. A few products, like those sold at the craft store Michaels, warn of potential cancer and reproductive harms, per California law. Many others simply say that the kits contain chemicals that may be harmful if misused and to read the cautions—which can only be found online.
Others provide outright misleading information. Blick Art Materials sells a brand called ArtResin, with 80% to 90% BADGE and a label that says BPA free, while only warning of skin irritation and allergic reactions. Online, the product is marketed as non-toxic.
Asked whether the company was aware of the health hazards of BADGE, a spokesperson told EHN, “Our formula is so pure everything reacts during the chemical reaction, and that makes it very safe for home use.” She directed EHN to a blog about BPA on its website where it claims that testing shows its fully-cured products contain only trace amounts of BPA that “are so infinitesimally low that we are able to say our epoxy resin is BPA-free.”
Brands sold on Amazon are particularly egregious. Unicone Art advertisements say, “With low odor and no fumes, our resin epoxy is non-toxic, making it 100% safe for you to work with for your casting, mold making and glazing projects.” It blacks out the chemical ingredients in its MSDS. Ecopoxy markets its FlowCast kit, labeled with a green leaf, as “thinner, clearer and more eco-friendly,” because it contains biorenewable content. Its kit is 40% to 60% BADGE. Some brands, like HXDZFX and Janchun have no websites other than their Amazon pages full of sparkly resin art supplies, which do not provide detailed safety information.A spokesperson for the American Coatings Association, Danielle Chalom, told EHN that the association was “unfamiliar” with the research on BADGE and therefore unable to comment.
Unknown health impacts
Meanwhile, back at Rockler, students discuss their home project ideas with Coleman. One is planning to build an L-shaped raised bed with an ensconced bench, and he may dabble with resin art to create some Christmas presents.
The doctor, who runs a nonprofit on children’s allergy issues, tells EHN she is concerned about the resin materials though she doesn’t know much about what’s in them. “I’m learning about them, as I work with them,” she told EHN.
As Coleman tidies the workbench, he talks about the time he researched urethanes and discovered just how little was known about potential health impacts.
“A lot of the safety issues won’t show up for a long time, [until] after you’ve messed up your body,” he said.
Banner photo: Palo Coleman shows his class how to use a router for cutting grooves in the resin-decorated wooden coasters they created. The black hose sucks the wood/resin dust, capturing via the workshop's HEPA air filtration system.
All photos taken by Meg Wilcox for Environmental Health News.