"The Achilles' heel of these studies is that there are so many things lab folks are exposed to, it's hard to nail down which exposure is a problem," says Grajewski.
"Estrogenic exposure is a problem throughout the developed world and there are many instances in which fish population health was degraded through the presence of estrogenic compounds," said Heiko L. Schoenfuss, director of the Aquatic Toxicology Laboratory at St .Cloud State University in Minnesota. .
"The key to the conversation is that TTHM [total trihalomethanes] is not a top health concern," it goes on to say, noting that only "chronic, longterm exposure" poses a problem, while suggesting that Flint's mayor was using the growing alarm to get public money.
The main methodologic problem in environmental epidemiology is exposure assessment, a problem that extends through all of epidemiologic research but looms as a towering obstacle in environmental epidemiology.
Although multidetector helical CT has taken the largest leap, MRI can be used in case of compromised renal function, severe contrast allergy, or in case radiation exposure is a problem, such as in children and pregnant women.
Several of the studies with positive findings are also based on aggregate measures of exposure, and although misclassification of the exposure is likely a problem in such studies, Feychting says, publishing only those with positive findings would give a false impression of consistency.
These low-level mercury exposures may contribute to cumulative environmental mercury exposure and present a problem for sensitive individuals who do not have adequate levels of glutathione and metallothionein and/or are deficient in the trace minerals needed for metal metabolism.
The objective of the present study, begun in 2011, was to determine if child lead exposure was still a problem in Dong Mai and after the study detected disturbing levels of child lead intoxication to identify likely exposure sources and management options.
For her part, Chizewer hopes the state may move to provide water filters to residents to help them reduce their exposure to lead, a problem she admits will not be an easy or cheap fix.
Although the PCR methodology is highly sensitive, the efficiency by which a ligand enters a particular organ following in vivo exposure may be a problem due to low penetration efficiency.
