By Mark Jones
I got skunked. Two groups published an idea I had before I could complete the research.
But let’s go back to the beginning. Ever the supportive spouse, I accompanied my wife for her colonoscopy in early May. But I had an ulterior motive; I wanted a sample from the IV bag.
A paper I saw provided my motivation, one that continues to get press. The research found microplastics in the heart plaques of cardiac patients. 12.1% showed PVC particles. It is one of the articles commonly quoted as proof we’re being harmed by microplastics in the environment and from food and drink. The elevated PVC struck me as curious. Ingestion studies show that PVC is a minor component of exposure. I developed a hypothesis — that elevated PVC in hospital patients comes from receiving IVs.
PVC is a very common medical polymer. I’m not certain what the IV bag my wife was using was made of. It might have been PVC; the line from the bag to her arm certainly was. I asked for the IV bag, which was well less than half used. The facility refused. I was able to grab a sample, about 40 mL.
I have a home-built Rayleigh scattering rig. I’ve tested lots of samples. My system has deficiencies but allows comparison. I can tell a lot from a little. My scattering technique cannot distinguish between plastic, inorganic, and biological particles. I rely on collecting the particles and looking at them under a microscope. It isn’t perfect.
The sample from the IV bag was filled with microparticles. I went about making PVC microparticle samples for testing. I was able to concentrate PVC particles from the suspensions I made and was able to investigate their properties. Everything pointed to the particles in the IV samples being PVC.
I hit the literature again. To my chagrin, others have identified IVs as a source of microplastics. I can’t believe it hasn’t gotten more attention. Studies showing minor shedding of particles from cutting boards get tons of press. Two studies show pretty unequivocally that IVs dose microplastics directly into the bloodstream end up largely ignored.
The studies show that IVs are a certain source of microplastics. One of the studies shows a time evolution, demonstrating the particle level is highest at the start of flow. Rinsing with as little as 12 mL reduces exposure.
Come December, it was my turn for a colonoscopy. I grabbed samples, again showing lots of particles. I haven’t done any further analysis, just the scattering showing many more particles than in the average disposable water bottle. It is not a fair comparison; it’s just that disposable water bottles are frequently vilified for their levels of plastic. The studies on IVs did not change behavior in Michigan. There was no line purging before the needle went into my arm.
It prompts pondering when we collectively know something and when evidence is sufficient to warrant action. We’ve been here with climate change, PFAS, alcohol consumption, and any number of other worrying studies. Even considering that there are microplastic particles present in IV bags doesn’t demand action. Presence fails to prove harm but suggests more studies are needed.
Many interpret the cardiac plaque study as evidence of harm caused by plastic. Particles in plaques could simply be the result of recent hospital exposure, not an underlying cause of plaque buildup. PVC use in medical applications began in the 1940s, and PVC still accounts for over 30% of all medical plastic with tubing for IVs being a significant use. With 80 years of experience, these are the first studies I can find questioning the risk. If plastic particles in IVs are harmless, as decades of use would suggest, there is no need to follow the recommendation of purging lines before use.
On the flip side, it seems like a pretty minor step to reduce exposure. Directly injecting microplastics into a vein doesn’t sound good. Two colonoscopies, an admittedly small data set, each used less than half an IV bag. Purging lines with 12 mL seems a minor perturbation until the science is settled.
Filed Under: Commentaries • insights • Technical thinking
