Dr. Heather Williamson is a 2000 graduate of KCOM and is board certified in family medicine and disaster medicine. She also has a CAQ in occupational medicine. She currently practices in the urgent care and occupational health settings with Mercy Hospital in St. Louis, Missouri. And as Jeffrey said, Heather is virtual, but she will answer questions. Heather, it's all you. Thank you, Dr. Clark. I'd also mention there's a couple of handouts, supplemental handouts she's provided on these two topics in your app. Okay everybody, we're here for the plastics and then the pesticide lecture. So with plastics, you have three major routes of entry. It can be inhalation, dermal contact, or skin absorption, and ingestion through the GI tract. The industry of plastics employs nearly three quarters of a million people, a large number of facilities, injury rate of almost four per 100 full-time employees, 59 work-related fatalities in the plastics industry in those three years, that 2013 to 2016. It's harder to find more updated information than that, but it is a massively profitable industry. Synthesis of plastics can give you some more toxic products than the final issue products. Compounding of the plastic with additives modifies the toxicity profile. You can get organic and epoxy plasticizers, stabilizers, fillers, colors, flame retardants, and all of that will change the end toxicity potential. Fabrication usually involves heat and pressure, molding, blowing, cutting, and grinding, again all can increase the risk of exposure to some of the compounds, and combustion and degradation, all of them decompose into other chemicals, many of them are toxic. So major categories of plastics are thermoplastics, which are heat resistant, things like acrylics, amides or polyamides, fluoropolymers, polyethylene, polyvinyl chloride, and polypropylene, and then there are thermosets, which are the amino resins, polyurethane, polyesters, and epoxy resins. So acrylics, we've all heard of acrylic fingernails, but they are a broad category of elastomers, polymers, they're pretty resistant to breakage, and they're common in fake nails, glue, and dental appliances. Exposure can be inhalational, skin, or through the eye. Toxicity, you can get both an irritant effect to the skin, respiratory system, eye, and mucous membranes, but on the skin you can also get allergic dermatitis, and that is sensitizing, which means each time that the person gets exposed to it again after they've developed that allergic reaction, they can have a more significant allergic reaction, and also to a smaller amount of the allergen. With methylmethacrylate, you can get hand and finger paresthesias. There's a possible link between methylmethacrylate and myoproliferative disorders, esophageal and breast cancer in women less than 36 years old. As you can see here, I have underlined some of the most important take-home messages here, so whenever you see it underlined, that tells you that that's a good thing to remember about these. The picture here, you can see some very characteristic appearing dermatitis related to acrylics, and you do see this somewhat commonly in people that work in nail salons, so kind of be on alert for that. It usually starts out more right around the fingernails and the tips of the fingers, but can be anywhere on the hands. If you can find a dermatologist that specializes in occupational exposures, you can do skin patch testing, neurological respiratory exams, but there's not a specific lab test for this. So the polyamides, which include nylon, they have applications in apparel and mechanical parts, exposure to nylon fibers can cause what they call flockworker's lung, and sometimes these nylon fibers remain in the lungs for a very, very long time. Some skin exposure can cause some irritation as well. It can cause allergic and irritant dermatitis. The irritant dermatitis is usually from dyes in it as opposed to the undyed part. Respiratory sensitization and asthma. Flockworker's lung is often misdiagnosed as asthma or recurrent pneumonia. Symptoms do improve days to weeks after cessation of exposure with respiratory asthma, but it can also be linked to bladder cancer, early breast cancer. Sometimes on CT scan of the chest, it'll have a ground glass appearance. For the Teflon fluoropolymers, the main risk is inhalation of vapors during the initial application of thermal processing, but there's a possibility for exposure with cookware that's heated way higher than it is meant to be. Seeing it solvent narcosis with the fluoropolymer resin airing off, it's called the Teflon flu, aka polymer fume fever, and it's very much a flu-like illness. Thermal degradation products start around 500 degrees Fahrenheit, so don't use your nonstick Teflon pan on the outdoor grill or get it way overheated on the stove. It can cause polymer fume fever about 12 to 24 hours after exposure, so it's not immediate, but it can cause some but you know chills, malaise, cough, shortness of breath. You can have actually an increased white blood cell count, so it starts to make you think bacterial, but in fact it's polymer fume fever. Chronic exposure can cause possible thyroid problems, ulcerative colitis, pregnancy-induced hypertension, kidney or testicular cancer, and strangely high cholesterol. We don't have a specific test for that. For polyethylene, it's the most common basic plastic we produce in the U.S., about 80 million metric tons per year. It's used in food and beverage containers, plastic bags, pipes, packing foam, and a whole host of other things. When you look at the little recycling symbol on various products, it is the one, two, or four in the little triangle. Exposure, main occupational exposure is inhalation of vapors during the thermal processing of it. It's very, very flammable and thermal degradation of it produces carbon monoxide, formaldehyde, and acrylin. Acrylin can cause occupational asthma and is a respiratory irritant, and obviously a large fire, especially in a plant that produces or contains a lot of the polyethylene, can cause a significant amount of carbon monoxide. So I don't think it's just if you see somebody who's inhaled the smoke from such a fire or been in an enclosed space with such a fire. It's not just the toxicity from polyethylene. Look for carbon monoxide poisoning. We don't have a specific test for polyethylene, but if you are concerned about the carbon monoxide, obviously you can get an arterial blood gas and carboxyhemoglobin level A. Vinyl chloride. It's a base for PVC. It's colorless gas. It can be inhaled during manufacture. It is the three in the recycling triangle. Toxicity, acute toxicity is narcosis, hepatitis, but you can have chronic exposure to it. It's a known carcinogen. It can cause liver angiosarcoma, but the really big tip-off that you don't see with probably anything else is called acroosteolysis of the phalanges. It's underlined. And the image there on x-ray is that it's basically just necrosis of the tufts on the fingers, the bone at the tufts of the fingers. You can also get Raynaud's phenomenon, COPD, cardiac arrhythmias, hyperkeratosis. Birth, potentially in pregnant women, can have fetuses or baby with birth defects, spontaneous abortions, brain, lung, and blood cancers. You can check and monitor liver functions and PFTs on people that work with this on a chronic basis, but really be alert for that acroosteolysis of the phalanges. It's kind of pathognomonic for that for vinyl chloride exposure. Polyvinyl chloride, it's still the three in your recycling triangle there. It's used to make solid hard plastics, but plasticizers can add some flexibility. It's used in pipes, wire insulation, furniture, construction. I'm sure we all have PVC pipes in our home. Once it's all set, it's not so big of a problem, but during manufacture, main route of exposure is inhalation. There's been an association in the past of PVC and meat wrappers asthma. However, they think that that may actually be more from a different compound that's in the labels. These are packages of meat when your meat's been processed and placed into a package, and that clear wrapper goes around it, that the heat shrink. They think it may be more from the labels than the actual PVC, but you can also have an irritant effect in the respiratory tract due to the thermal byproducts if it gets hot. There have been reports of scleroderma and pulmonary fibrosis with chronic exposure to PVC dust. Again, no special tests for that. Polypropylene, again, something else I'm sure we all have at home. It resists solvents and acids. It's used very frequently in prescription bottles, such as the one here for Skittles. Food containers, plastic bags, and other packaging, again, main road of exposure occupationally is inhalation. It is highly flammable. Again, the thermal degradation products can cause asphyxiation and respiratory irritation, so you don't want to be around these when they're burning. They also put additives in there, such as biocides. They can also be toxic, but again, more during the actual production of it than just having the plastics sitting around. The polypropylene is the five in your recycling triangle. For amino resins, they're used in coatings for paper and textiles and in medium density fiberboard. Medium density fiberboard is that particle board that we all had in our furniture in college and med school. Main route of exposure is inhalation in skin. It can cause toxicity from allergic dermatitis, respiratory mucous membrane irritants. Systemic symptoms include headache, nausea, vomiting, fatigue with the urea formaldehyde. Thermal degradation, again, when it burns, it releases carbon monoxide, formaldehyde, ammonia, and cyanide, and all of that can cause irritation and asphyxia. Again, if you've got somebody that works in a place with a lot of this MDF present or they manufacture it, you've got to be alert for those things if it burns, especially the carbon monoxide and cyanide. I think sometimes when you have a fire with these, people overlook the potential for carbon monoxide and cyanide in favor of just thinking it's direct smoke inhalation, but it's not. No special lab tests for this, again, except unless you're looking for carbon monoxide or cyanide poisoning from a fire. Formaldehyde can also be released from cutting and sanding the MDF, so got to keep that in mind too. All right, on to isocyanates or polyurethane. Polyurethane is a polymer of isocyanides. It's used in foam, insulation, protective coatings, paint, furniture, especially like polyurethane like cushions. Once it's reacted, it's chemically inert and safe, but during manufacture of it, you can get exposure via inhalation, skin, and eyes. So isocyanates come in a variety of different versions. I have those for methylene, diphenyl isocyanate, toluene isocyanate, hexamethylene isocyanate, and isoforone isocyanate. The big problem that you're most likely run into really is respiratory sensitization, asthma, and hypersensitivity pneumonitis, although they can also get allergic and contact dermatitis. And again, this stuff is sensitizing, so once a worker is sensitized, they can have no future exposure to this, not even with PPE, because they can have a significant reaction to even an amount of this that is well below the permissible exposure limit. Rare cases can cause corneal burns, pulmonary edema, COPD. Again, when this stuff burns, it is bad. Burning plastic is bad. You can get isocyanates re-released from the burning polyurethane. You can get hydrogen cyanide and carbon monoxide. Again, if you can find somebody to do a skin patch test, that is a potential to determine if someone has been sensitized to the isocyanates. And you can monitor PFTs. So, the Bhopal disaster in India was a problem of isocyanate release, so 40 metric tons of methyl isocyanate was actually released from the Union Carbide plant in Bhopal, India. About 700,000 people were exposed to the isocyanates in the middle of the night, and it caused nearly 4,000 deaths. They had 38,000 or so temporary partial injuries and approximately 3,900 severely and permanently disabling injuries. In October 1984, the tank that contained 42 metric tons of methyl isocyanate was supposed to be pressurized with nitrogen, but wasn't holding that nitrogen, and therefore, the methyl isocyanate could not be pumped out. So, several vents of gas scrubbed the tank, the water leaked into the tank and caused a runaway exothermic reaction, accelerated by high ambient temperatures and iron from the corroded pipes. Two different senior refinery employees assumed the reading was an instrumentation malfunction. So, at 11.30 p.m. that night, workers in the area at the plant were told that there was a leak in the tank, and that they had at 11.30 p.m. that night, workers in the area at the plant were feeling the effects of minor exposure and began to look for a leak. They found it by 11.45 p.m. They reported it to a supervisor on duty at the time. The decision was made to address the problem after a 12.15 a.m. tea break, and in the meantime, employees were instructed to continue looking for leaks. Five minutes after the tea break ended at 12.40 p.m., the reaction in the tank reached critical state. Temperatures were off the scale, maxed out beyond the measurable limit, and the pressure in the tank indicated 40 psi. One employee witnessed a concrete slab above the tank crack as the emergency relief valve burst open, and the pressure in the tank continued to increase, even after atmospheric venting. Direct atmospheric venting should have been prevented, or at least partially mitigated, by at least three safety devices which were not working appropriately, not in use, or insufficiently sized. So, you know, there were all these problems you can see here. The vent gas scrubber was turned off. The water curtain that was supposed to douse all of this was not designed to be high enough to reach the gas. The flare tower that was designed to burn off the gas wasn't working because the connecting pipe had been removed. The Freon from a refrigeration system was shut down in June to save money, and the Freon shipped to other plants, and then the storage tanks were obviously inadequate since water leaked into there. So anybody that thinks that OSHA is a giant pain in the rear, which they are, it's things like this that point out the need for significant plant safety and standards. Anyway, moving on to polyesters. It's used for fabrics, cushions, spray-on films, LCDs, filters, and I'm sure we all remember the polyester leisure suit of the 1970s. Main exposure during fabrications, inhalation, or skin. It's overall low toxicity, but it can be sensitizing. So it's a limited respiratory and dermatological irritant, but can be sensitizing, so then you end up with somebody who cannot continue to work around polyesters. The fibers may also hang out in the lung tissue and stay there for extended periods of time. Epoxies. We've probably all seen these in the little two-syringe mixer that you have to mix up at home. It's a wide application in adhesives, paint, circuit boards, coatings, main route of exposures, inhalation, or skin. It can again cause both allergic dermatitis or irritant dermatitis. It gets in the eyes. It can cause conjunctivitis. It is also a respiratory sensitizer, so it can cause occupational asthma. Some epoxy resins also contain bisphenol A, which is an endocrine disruptor and increases the risk for prostate cancer. Occupational exposure to BPA is about 10 to 20 times greater than the general population's exposure through commercial and consumer products, but 90% of people in the U.S. have detectable bisphenol levels in their blood, so there has been a move over the last decade or so to get bisphenol A out of a lot of the cups and plates and plastic plates and that sort of thing. Can do skin and respiratory exams for that. The confounder with a lot of these exposures is that most plastics have a lot of additives in them. Everything from lead, cadmium, zinc, boron, phthalates, colorants, fillers, foaming agents, flame retardants, stabilizers, sulfants, and all of that stuff can have its own separate toxicity profile. So you have to get these safety data sheets from the employers, find out what else was in what else had been used in the plant at the time and or what might have been in these things that burned if there was a fire. Any questions? I have a question. You mentioned that people exposed to isocyanates can't use them again, even in PPE. What kind of PPE usually contains those isocyanates? I actually meant that you can't just put somebody in PPE who's sensitized to isocyanates and then send them back into their previous position. It's not that there's PPE and there's isocyanates in their PPE. It's that you can't take somebody who's sensitized, continue to expose them, and think that you're fine just if you put them in some gloves or you know a respirator or something. They can still get exposed in even very small amounts that can cause serious allergic reactions. Gotcha. Thank you.

family and disaster medicine

plastics exposure

thermoplastics and thermosets

toxicity risks

personal protective equipment

Bhopal incident