An article published in today s JAMA Pediatrics purports to link premature birth to exposure to the group of chemicals known as phthalates. These are plastic softeners-plasticizers, and are also found in numerous household products and cosmetics and shampoos.
In fact, this so-called study is a typical product of those researchers whose goals are rather than the advancement of science, knowledge, or public health to advance their own agendas and careers by propelling the anti-chemical bandwagon to which they have attached their stars. Despite all the self-expressed plaudits with words such as elegant, robust, and solidifies, anyone with an inkling of insight into valid epidemiological methods will smell a rat almost immediately.
The authors all with well-padded CVs bespeaking their environmentalist creds chose to evaluate a large number of possible urinary metabolites, as they announce in their methods section. However, they report results based upon one specific chemical only, and one of its metabolites. They also selected various cut-off points based on retrospective reviews of their data anathema to any good study actually seeking a possible valid link, leading to a cause-and-effect relationship and managed to come up with some statistically significant associations between the phthalate metabolite in the pregnant women s urine (DEHP, if you must know) and early delivery, i.e. before 37 weeks gestation.
What happened to all those other chemicals ostensibly analyzed? The blaring press release from the journal states that The study results indicate an association between increases in some phthalate metabolite concentrations in urine during pregnancy and higher odds of preterm birth. This clearly indicates that numerous other metabolites were assayed, allowing the authors to pick and choose among various results and slice and dice the cut-off criteria to attain the desired goal: Statistical Significance, and Journal Publication! (While the authors and the well-known anti-phthalate crusader, Shanna Swan, who wrote the accompanying editorial, are careful not to invoke a cause-and effect link, the journal s press group was not so coy: Preterm Birth Risk Increases for Pregnant Women Exposed to Phthalates, it alerted the concerned reader).
ACSH s Dr. Gilbert Ross had this to say: Here s another stinkeroo from the folks who brought you many other anti-chemical studies , based either on high-dose rodent tests or, like this one, with some human connection (however tenuous and attained only with the twistiest of data manipulations). These types of distortions of sound science are well-known to the editorial writer, Shanna Swan, whose infamous work on phthalates and ano-genital distance has been roundly satirized in the responsible literature and it goes without saying never replicated (and never will be, I daresay). As with that study, scientists would love to have access to the raw data used to cobble this junk together, but none will be forthcoming, as per their usual tactics of evasion. The real villains here again, hate to be repetitious are JAMA and its Pediatrics progeny, whose willful blindness as to the scientific method and editorial responsibility is shameful, and has come to be expected, sadly.