Environmental Engineering Reference
In-Depth Information
may not always follow a monotonic relationship between dose and effect, particularly at
lowdoses.Forexample,bisphenolAinmicecanshowahump-shapeddoseresponsecurve
for tumour development, where “moderate” exposure produces the highest frequency of tu-
mour development. Other dose response curves are possible. For example, the oestrogen
mimic p-nonylphenol shows a complex U-shaped curve in some species, while the pesti-
cide atrazine can produce a greater effect at lower doses than at high doses.
Studies also show that the developing human brain is particularly vulnerable to dis-
ruption, especially at apparently short periods of exposure during prenatal development.
As early as 2000, a U.S. National Academy of Sciences expert committee estimated that
3% of neurobehavioural disorders are caused directly by toxic environmental exposure and
another 25% by interactions between the environment and inherited susceptibilities. In a
short review paper published in 2012, Philip Landrigan and colleagues listed nine groups
of substances that have been implicated in developmental neurotoxicity, leading to autism
and learning disabilities. They are lead, methylmercury, PCBs, organophospate pesticides,
endocrine disruptors, automotive exhaust, PAHs, brominated flame retardants and perflu-
orinated compounds (our PFAS). The list looks so familiar to the Arctic Messenger. All
the substances - even the “generic” automotive waste - have been shown to be capable
of long-range atmospheric transport. No country or region is immune from the toxic emis-
sions of another region. Most of the substances on the list are capable of biomagnification
and most have been implicated in low-dose epidemiological effects in Arctic and non-Arc-
tic human populations. From our earlier study, we understand how physical and biological
processes conspire to make this happen, but I am often asked if these neurological and be-
havioural effects are significant. It is a question I find downright repugnant at the personal
level. Should a person be labelled a luddite for questioning the morality of allowing per-
sistent substances to enter the environment that we anticipate will increase the proportion
of children born with intellectual deficits and behavioural disorders?
There is another way the information can be presented. Think of intelligence as being
an attribute that has a financial value to society. Next, consider its measurement as IQ be-
ing represented as a simple bell curve in the population of a country or region. The bulk of
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