It annoys me when news stories don't link to their sources. Here it is: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2605.2009....

The study is terrible. All the reported effects include 0 well within the 95% confidence interval (e.g. ranges like -2.3 to +3.2), yet mysteriously the P values end up just the right side of "significant". This reeks of confirmation bias, or worse.

Well, no, there are a couple of intervals that don't include 0 and those are the ones they report.

Other than that, this does look like a pretty poor study. They do that classic (but misguided) thing where they say that their study was conducted on a small sample and so the fact that they found anything at all is super-duper-extra telling. In reality, it just makes it more likely that any effect that is reported will be exaggerated – as was brilliantly pointed out by Andrew Gelman and John Carlin in http://www.stat.columbia.edu/~gelman/research/published/retr....

Accounting for multiple testing by Bonferroni, none of the results is significant (at least, none reported in the abstract).

And since they're doing multiple tests, 0.05 isn't even a stringent enough threshold: https://xkcd.com/882/

Actually, it's worse than that - theoretically, they should be doing an F-test, but those are essentially useless[0] except as exercises for unfortunate undergraduates.

This gets into the flaws with hypothesis testing (and p-values) as a tool altogether, though. And while I would love to see the natural sciences eschew these rather rudimentary heuristics in favor of the more sophisticated modeling tools that we already have, I'm not holding my breath on that happening anytime soon.

[0] http://andrewgelman.com/2009/05/18/noooooooooooooo/

I'm glad someone looked up the actual paper. Not surprising that the findings were weak.

I couldn't see the article, only the abstract. But what they report in the abstract is some regression coefficients for a "masculinity score" and associated p-values. A very simple analysis, and not much that can go wrong there.

My only concern is with cherry picking the chemicals. It wasn't clear if they were only reporting specific chemicals that had significant relationships, or if all the chemicals that would be expected to have a significant relationship did.

The experiment:

The women, who gave birth to 74 boys and 71 girls, were followed up when their children were aged four to seven and asked about the toys the youngsters played with and the games they enjoyed.

The result:

They found that two phthalates DEHP and DBP can affect play behaviour. Boys exposed to high levels of these in the womb were less likely than other boys to play with cars, trains and guns or engage in "rougher" games like playfighting.

  DEHP - used to make PVC soft and pliable, used in products like flooring

  DBP - used as a plasticiser in glues, dyes and textiles

I recently read an article on a similar topic: https://medium.com/@GregDowney1/plastics-tiny-penises-and-hu...

On the other hand...

>Porn and video game addiction are leading to 'masculinity crisis', says Stanford prison experiment psychologist

http://www.independent.co.uk/news/science/porn-and-video-gam...

That's probably the worst article that I've read in the last year.

Meanwhile the opposite from another psychologist:

>Research on exposure to television and movie violence suggests that playing violent video games will increase aggressive behavior. A meta-analytic review of the video-game research literature reveals that violent video games increase aggressive behavior in children and young adults. Experimental and nonexperimental studies with males and females in laboratory and field settings support this conclusion. Analyses also reveal that exposure to violent video games increases physiological arousal and aggression-related thoughts and feelings. Playing violent video games also decreases prosocial behavior.

http://pss.sagepub.com/content/12/5/353.abstract

Even exposure to a even just a picture of a gun may cause an increase in aggression:

https://en.wikipedia.org/wiki/Weapons_effect

I have wondered, assuming the effect is real, if the "problem" of media causing violence is even socially solvable if we are psychologically this sensitive.

Related re: BPA / estrogen: http://m.toxsci.oxfordjournals.org/content/114/1/1.full

BPA was replaced but the alternative is just as bad.

By the way BPA is still in the thermal paper used for cash register receipts.

Should probably be marked in the headline that this is from 2009.

I'd really prefer a link to the actual study or paper, because this sounds a little... biased, to say the least. More specifically, it sounds like the whole "Bisphenol A" thing [1] and from even before that, the "soy mimics estrogen" thing [2].

There's nothing new under the sun.

1: http://www.fda.gov/newsevents/publichealthfocus/ucm064437.ht...

2: http://well.blogs.nytimes.com/2013/09/27/ask-well-is-it-safe...

I've never heard a single thing about concerns over PVC until today. Before I even saw this article on HN I was in the process of researching it because a friend brought up how their dad told them not to drink the water from their faucet because it's running through PVC. I'm in the process of buying a house that has new PVC all over and I can't find any reliable info on this concern. Does anyone here have any sources to share?

Most new water pipes in cities are made from PVC, so it's not just what your house is made from you need to think about. I expect you could also find articles talking about metal leaching into water being bad too. Short of distilling your own water I don't know what you can really do.

You can get a reverse-osmosis water filter. Mine fits under my kitchen sink. I love it.

So, you mean that in ancient Rome/Greece people used plastics?

I find a small part of me wondering if this wouldn't actually be kind of a win for humanity.

The term feminisation as used in the article title is actually not what you think it is. I'm not in your head, but I would guess you're associating feminisation with being nicer, less aggressive, less violent, less hateful, more loving, more caring, prettier, and other such positive things (which incidentally are more associated with oxytocin than the xenoestrogens, bpas, and whatnot that they're talking about), but here, feminisation strictly means a hormonal imbalance.

You can argue the accuracy and the validity of the science all you want, but the observed effects of this so-called "feminisation" is penis-related birth defects for boys and earlier puberty + menopause for girls. You are, of course, entitled to your own opinions and views on this matter, but as a man, I personally would prefer to have as large and functional penis as naturally possible.

This could be more charitable. The very first sentence of the linked article says "less likely to play with boys' toys like cars or to join in rough and tumble games", so it would be reasonable to assume they're talking about behavioral changes is that vein.

So to be completely fair, I'd break it up into two parts:

1) Given our current understanding of endocrinology, anything that alters the hormonal balance of children is probably not what you'd call a "good idea".

2) However, if something were to make the behavioral patterns of male children more closely resemble those of female children, that effect might not be bad for a society.

And I'll put forward, hesitantly, that the strong pushback against this idea has less to do with the obvious (1) and more to do with the deeply controversial (2).

This definitely captures the spirit of my off-the-cuff remark, thanks.

If some sort of "social feminization" were a productive idea (and I'm not saying I truly believe it is), I wouldn't advocate accomplishing it through medication, let alone haphazard doses of environmental chemicals.

Wow, can you imagine the reaction you would get if you made the reverse suggestion? You are making so many assumptions- here is something to challenge your beliefs: http://www.ncbi.nlm.nih.gov/pubmed/19997098?dopt=Abstract&ho...

How many assumptions can I possibly exhibit in a one-sentence comment? It seems to me you're assuming a lot about my assumptions and beliefs.

I appreciate the link though, that's pretty interesting.

The article itself talks about less "playfighting" so it's not exactly an "assumption" of the OP. Perhaps it's an assumption of this study.

> Girls' play

So a lack masculinity is equal to femininity? Yay gender binaries