| ▲ | sigmoid10 2 hours ago | |||||||
You'll excuse me if I only explain the first one, since the others seem redundant (not to say suspiciously redundant if you look at the authors). And none of this is a meta review like I asked, but I'll let it slide this time. First: >no significant association was found between MP exposure and sperm concentration or total sperm count Second: N=34 Third (if second didn't give it away): The one effect they did find sits at p=0.056. That means one in 18 random studies will find that effect just because of probability statistics. And as you have nicely pointed out, there are maaaany studies like this out there. You just don't find all the null results if you go into research with your mindset. But that is exactly what differentiates a scientist looking for truth from a hobbyist trying to argue on the internet. | ||||||||
| ▲ | dijit 2 hours ago | parent [-] | |||||||
You asked for a meta-analysis. Here's one: 39 studies, published in the Journal of Hazardous Materials: https://www.sciencedirect.com/science/article/abs/pii/S03043... It found microplastics caused a decrease of 5.99 million/mL in sperm concentration, 14.62% in sperm motility, 23.56% in sperm viability, and a 10.65% increase in sperm abnormality rate. (I copied and pasted these values directly from the source). You said you'd be "onboard immediately" if someone showed you a rigorous causal link. This is a meta-analysis with an adverse outcome pathway mapping the causal chain from molecular initiating event (ROS) through to tissue-level damage. That's about as rigorous as it gets before human clinical trials, which (for obvious ethical reasons) nobody is going to run. As for the p=0.056 critique: you picked the weakest single data point from one of four links and declared victory (scientific!). The in-vitro study I linked exposed actual human semen to microplastics under controlled conditions and observed time-dependent decline in motility and increased DNA fragmentation. That's not a simple correlation, it's a direct causal experiment on human tissue. You didn't address it. The goalposts have moved from "show me evidence" to "show me a meta-review" to "well not THAT meta-review." At some point you have to engage with what the research actually says rather than with what you'd like it to say. | ||||||||
| ||||||||