I first became interested in this topic when a paper came out in the New England Journal of Medicine for patients who had undergone carotid surgery, they actually found micro- and nanoplastics in a significant proportion of the carotid plaques that were removed. Those plaques that had the micro- and nanoplastics had more inflammation and more clinical events associated with it. This got me thinking, if micro- and nanoplastics are literally everywhere in every organ and tissue of the body, might they be associated with cancer? 

As a urologist, I’m primarily focused on prostate cancer research, so I wanted to start there, so got together this collaboration to start looking at micro- and nanoplastics in prostate tissue. 

What was the study design? 

It took a long time to get this whole study set up just because there is so much plastic even in the operating room and the pathology lab and the laboratory so creating procedures to try to minimise the amount of plastic exposure that these samples might have along the way took really a lot of buy-in from the personnel in the operating room and the pathology lab to curate these samples. Eventually we were able to collect samples from patients who were undergoing radical prostatectomy for prostate cancer, and from each of the patients we took a sample from the tumour and also a sample of benign tissue from the opposite side of the prostate to be able to compare. 

We used two different methods to look for micro- and nanoplastics: Raman microspectroscopy and pyrolysis-GC/MS. These approaches each have strengths and limitations so we’re trying to increase rigour by using multiple methods. Basically what we found through this combination of methods is that nine of the ten patients that we have analysed so far did have microplastics in their prostate. This is literally things like pieces of a water bottle in the prostate, and that the concentration was higher in tumour tissue compared to the benign tissue samples from the other side of the prostate.  

What were the results? 

So the findings were that nine of the ten patients had micro- and nanoplastics in the prostate tissue and that the concentration was higher in the tumour tissue than the benign tissue.  

What impact could these findings have? 

This is very early data, so this is only ten patients, so I think it would be too early to make any kind of strong conclusion like to say that microplastics are associated with prostate cancer risk, but this is definitely something that we’re continuing to study. We have a grant from the Department of Defence so we’ve now collected over 30 samples, so we’re continuing to process all these samples to increase our sample size.

We also really want to look at some other things like for example, what is the association with tumour grade. So once we have more cases we will be able to look at differences. For example, in this first ten patients there was one patient who had high grade disease and had very high levels, but that’s one single case, so it’s not something that we could make any conclusions, so we really need to increase our numbers. 

I would say in the meantime, certainly there’s growing evidence to suggest that micro- and nanoplastics themselves, but more so that chemicals associated with plastic, can have negative health impacts. Not to mention that there’s such a harm to the environment from the growing amount of plastic. I think that we could safely say, regardless of this study, that we should all be thinking about how we can reduce our use of plastic, whether it’s storing food in non-plastic containers, trying to reduce the use of single-use water bottles, not using plastic pods in the dishwasher. Just on an everyday basis, what can we do to try to cut back on this massive societal problem. 

What could be the mechanism for microplastics increasing cancer rates? 

There’s a couple of possible mechanisms. One that we’re looking at as part of this grant from the Department of Defence is inflammation. As I mentioned earlier, in the original study that inspired this work looking at the carotid plaques, the plaques that had micro- and nanoplastics had more inflammation, and inflammation is certainly something that can be associated with cancer development so we are looking at these tissue samples to see if there was an association between the concentration of micro and nano plastics with inflammation as a possible mechanism. 

Another possible mechanism is that it is the chemicals associated with plastic, so there are chemicals, for example things like phthalates and bisphenols, which are endocrine-disrupting chemicals that are associated with these plastic particles. So it could also be that the plastic piece itself is a vehicle through which these chemicals are getting into these tissues and that they are exerting endocrine-disrupting effects that are associated with cancer. 

I think there’s a lot of different possibilities, and hoping that over the next year we’ll be able to get more data on this to parse this out a bit more.