Possible link between Alzheimer and DDT.. wait, that DDT??

A team of researchers from Rutgers (yay!) and Emory University published a paper today in JAMA Neurology showing that folks with Alzheimer Disease (AD) had higher levels of DDE circulating in their blood and risk was also modulated by a genetic component.

DDE is one of the products of DDT when it breaks down. In the parlance of environmental chemistry we would just say that DDE is a DDT metabolite. I suspect that the current generation in college has never heard of DDT yet everyone over 45 probably has. This molecule was banned for use in the US in 1972 by the EPA. Yup, we stopped widespread spraying of DDT forty-two years ago. What the hell is it doing in blood at levels that may induce AD?

A few points may shed light on this

1. DDT is a persistent organic pesticide that is stored in human body fat - apparently for long periods of time. So those people exposed to DDT in before the ban may still have dangerous levels in their blood

2. DDE is amazingly persistent in soil, such that DDE becomes recirculated in the environment when we dredge (dig in rivers) and through the action of earthworms. Once in the environment, DDE is able to enter food webs and end up in bodies.

3. DDE circulates widely. DDE is stable in water and soil and be transported in the atmosphere. DDE is still showing up in Arctic predators where, to my knowledge, DDT was never used. 

Birds, particularly fish eating birds, such as pelicans and Bald Eagles, and birds that consume other birds (including those that eat fish), such as Peregrine Falcons still show DDE in eggs and blood. And these birds are not over 40 years old. So there is also the potential that we are still consuming DDE when we eat fish. Is anyone looking for DDE in fish? Not sure. It would be small amounts. But that's the problem with molecules that bioaccumulate, small quantities add up over time. Dilution is not the solution to pollution. 

Willing or not, we are still consuming many contaminants that accumulate in our bodies including phthalates and flame retardants. The effects? Not sure. But I doubt we can be as indifferent as we were in the past as shown in this video. 

References:

Clark, K., et al. (2009). "Organochlorine Pesticides, PCBs, Dioxins, and Metals in Postterm Peregrine Falcon (Falco peregrinus) Eggs from the Mid-Atlantic States, 1993–1999." Archives of Environmental Contamination and Toxicology 57(1): 174-184.

Fisk, A. T., et al. (2005). "An assessment of the toxicological significance of anthropogenic contaminants in Canadian arctic wildlife." Science of the Total Environment 351: 57-93.

Grier, J. W. (1982). "Ban of DDT and subsequent recovery of Reproduction in bald eagles." Science 218(4578): 1232-1235.

Jagannath, A., et al. (2008). "Eggshell pigmentation indicates pesticide contamination." Journal of Applied Ecology 45(1): 133-140.


Nilsen, E., et al. (2014). "Contaminants of legacy and emerging concern in largescale suckers (Catostomus macrocheilus) and the foodweb in the lower Columbia River, Oregon and Washington, USA." Science of the Total Environment(0).

Stemmler, I. and G. Lammel (2009). "Cycling of DDT in the global environment 1950–2002: World ocean returns the pollutant." Geophys. Res. Lett. 36.