Following on from my previous post, let's see how this fits in with the spatial epidemiology of PD.

As we've done before, we start with the paper by Willis et al. [1] which shows geographical variations in the incidence [2] of PD across the US. Roughly speaking, the west has low incidence and the east (from Texas north-eastwards) has high incidence.

If aluminium plays a part in the aetiology of PD, its spatial distribution, as far as ingestion is concerned, should match that of PD.

Where does the aluminium come from:
- pots, pans, cans;
- water;
- food
- pollution.

The aluminium content of food and water will, to the extent that it is sourced locally, in part, depend on the amount of aluminium in the soil. The distribution of this across the US is given by Shacklette and Boerngen [3]. It shows almost the opposite distribution to that of PD:
Average aluminium content either side of 96th meridian
West 5.8%
East 3.3%

However, what probably really matters is the rate at which the aluminium leaches from the soil. This will depend, in part, on the pH of the rainfall [4] which is high to the west (an "eye-balled" average of 5.5) and low to the east (4.6).

It turns out that this difference has a completely disproportionate effect on solubility [5]: going from a pH of 5.5 to a pH of 4.6 the solubility quadrouples. This more than makes up for the original lower level of aluminium.

This acidity has a double whammy: it leads to greater leaching from pots, pans and cans.

No claim is made that aluminium is the cause of PD. Rather, we have shown that a role for aluminium in the aetiology of Parkinson's is not blown out of the water by the epidemiological evidence.

References

[1] "Geographic and Ethnic Variation in Parkinson Disease: A Population-Based Study of US Medicare Beneficiaries"
Willis A., Evanoff B., Lian M., Criswell S., Racette B.
Neuroepidemiology. 2010 April; 34(3): 143–151.
Published online 2010 January 15. doi: 10.1159/000275491
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865395/

[2] http://www.ncbi.nlm.nih.gov/pmc/arti...395/figure/F2/

[3] "Element Concentrations in Soils and Other Surfici 1Materials of the Conterminous United"
U.S. Geological Survey professional paper 1270
Shacklette H., Boerngen J.
http://pubs.usgs.gov/pp/1270/pdf/PP1270_508.pdf

[4] "Acid Rain and Acid Deposition"
http://oceanworld.tamu.edu/resources.../acidrain.html

[5] "Soil Aluminium and Soil Test Interpretation" http://www.spectrumanalytic.com/supp...rpretation.htm

John