While the study certainly admits that there is much that we don't know. It confirms a lot of what we do. And it ain't pretty. As many as 1 in 6 US children suffers from some sort of neurodevelopmental disorder, including Autism, hyperactivity, speech delay and ADHD.
Please read the entire article here, but in case you don't get to it this is a rather long excerpt that I found incredibly compelling:
We are beginning to learn more about how these substances may alter brain development. Their strategies are complex and varied. Under the influence of methylmercury, for example, the brain’s nerve cells “are lying helter-skelter, not in their usual logical locations,” says Grandjean. Pesticides are designed to be neurotoxicants—that’s the whole point—and some, like chlorpyrifos, work by inhibiting cholinesterase, an enzyme critical to brain-cell communication. Different neurotoxicants affect children differently. At high levels, methylmercury appears to cause memory deficits, while lead primarily decreases attention span and pesticides tend to impair spatial perception. Black carbon apparently affects attention and processing speed.
Not all kids are equally vulnerable. Other factors matter, like genes, psychosocial stress, and, interestingly, gender. Boys tend to be more vulnerable than girls to the deficits associated with PAH. Studies of prenatal exposures to phthalates and bisphenyl-A (BPA), both endocrine disruptors, also show gender differences. Phthalates are considered anti-androgens, while BPA acts like an estrogen, and the developing brain takes important cues from both hormones. With chlorpyrifos exposure, for example, boys have greater difficulty than girls with working memory.
Many of these substances disproportionately affect the poor, but not all. Poor kids are exposed to more lead and first- and secondhand tobacco smoke. More affluent populations accumulate more mercury from their diet. Urban kids may be exposed to more PAH and black carbon, farm kids to more pesticides and arsenic from well water.
Of all the suspects, brominated flame retardants may be the most democratic. Although levels of PBDEs are now dropping in pregnant women, Americans still have the highest levels tested anywhere in the world. Flammability standards enacted in California in the 1970s resulted in the addition of PBDEs to everything from electronics to home furnishings nationwide. Unfortunately, the molecules easily migrate, accumulating in blood and breast milk and persisting for years. Structurally similar to PCBs in some cases, they appear to interfere with thyroid hormone signaling, either by directly altering the amounts of hormone or by blocking the hormone transporters. As researchers learned from studying cretinism, thyroid hormones are critical to brain development, among other functions.