For years, researchers have puzzled over the surprisingly high
levels of aluminium that turn up in the shrivelled brains of Alzheimer's
disease victims. While some scientists believe that the aluminium
deposits are only a side effect of Alzheimer's, a growing number
of investigators say that aluminium may play a central role in causing
the disease that afflicts mostly elderly people. Aluminium occurs
naturally in some waters but is also introduced as aluminium sulphate
by some municipal water departments to remove fine particles, color
and bacteria. Municipal water departments usually control the water
to a slightly alkaline condition, i.e., pH between 7 and 8. In alkaline
conditions aluminium precipitates as fine solid particles, which
are then filtered out by means of sand filters. However, sand filters
become less efficient for particles as small as 4 to 5 microns and
therefore fine particles slip through.
The latest evidence of a link emerged when Australian scientists
reported that aluminium used to purify water accumulated in the
brains of laboratory rats. The Australian study focused new interest
on the issue at a time when Ottawas environmental health directorate
is preparing to propose Canada's first national guidelines for aluminium
levels in drinking water. The Australian study was important, said
the directorate's chief, Dr. Barry Thomas, because it showed that
aluminium in drinking water can be absorbed by the body. "As
to whether it actually causes memory loss and brain damage,"
added Thomas, "there is not conclusive evidence. But we fear
that it may." Although tiny amounts of aluminium are used in
a variety of products, including antacids, antiperspirants, and
some processed foods, the metal is pervasively present in drinking
water. The reason: municipalities in Canada and other countries
often use aluminium sulphate, or alum, to remove mineral particles
from water in filtration plants, a process that leaves an aluminium
residue in the water.
In the past, studies in Canada and other countries have pointed
to links between aluminium and Alzheimer's. University of Toronto
researchers found in a 1991 study that they could slow the rate
of deterioration in Alzheimer's patients by treating them with a
drug that removed some aluminium from their brains.
In a far-reaching study published in January (1995), William Forbes,
a university of Waterloo gerontologist, demonstrated an apparent
connection between mental impairment and aluminium in about 100
Ontario communities. In each community, researchers determined the
amount of aluminium in the water supply and tested the mental state
of people starting at the age of 45 and continuing over a period
of 35 years. They concluded, said Forbes, that the risk of impaired
mental functions was "almost 10 times higher in areas where
the aluminium levels in drinking water were high."
Since Doulton ceramic filter elements efficiently filter to less
than 1 micron; they effectively remove most of the residual aluminium.
200ppb (parts per billion) is the maximum level likely to be encountered
in our water supply. It is also the maximum allowable level stipulated
by the EEC regulations but the recommended guide level is 50ppb
More articles on the dangers of Aluminum.