Using a world first technique, CSIRO has found convincing evidence that the use of alum - aluminium sulphate - to treat drinking water is safe.
"We found that the aluminium we get from alum-treated drinking water is such an insignificant amount we don't need to worry. Only 1-2% of our daily intake of aluminium comes from water and of this, only the barest trace is absorbed. Much of the aluminium that is absorbed is then excreted in urine," CSIRO scientist Dr. Jenny Stauber says.
The results have significance for water authorities around the world who use alum to clarify drinking water as part of the water treatment process. Alum is later filtered from the water, but a small fraction dissolves and is not removed.
The cause of Alzheimer's disease is subject to international research. A variety of possible causes have been considered however no link between aluminium intake and Alzheimer's has been established. However some conflicting evidence in earlier studies suggested that aluminium that is left in treated drinking water may be more readily taken up by the body than aluminium from other sources.
"Aluminium is the Earth's third most common element and occurs naturally in food and water. Most of the aluminium we consume in our food and drinking water is not absorbed and goes straight through our bodies to be excreted in faeces. What we were interested in was the trace that is absorbed into our blood," Dr. Stauber says.
"If aluminium from water were to significantly increase the total amount of aluminium in the human body, it would have to be in a form that is much more easily absorbed into our bloodstream ( i.e. more bioavailable) than aluminium in food (which has low bioavailability). This is because a greater proportion of our daily intake of aluminium comes from food," Dr. Stauber says.
"We were able to calculate that aluminium from alum-treated drinking water would contribute less than 1 per cent to our body burden of aluminium over a lifetime. However the good news is that a related study on food shows that even what we get from food is well within the safe limits determined by the World Health Organisation," Dr. Stauber says.
A technique normally used for measuring trace minerals in environmental samples, was adapted to measure the amount of aluminium in blood and urine. The new technique was able to accurately detect lower levels than could ever be measured before.
"Using this technique we were able to draw a more complete picture of how the human body copes with aluminium. Before this was developed, this kind of work could not be done because changes in aluminium in blood and urine were too small to be measured using existing methods," Dr. Stauber says.
Funded by the Water Services Association of Australia (WSAA) and conducted by the Centre for Advanced Analytical Chemistry at CSIRO Energy Technology, the study analysed the amount of aluminium in the blood and urine of 29 healthy volunteers aged between 36 and 76, while on a strictly controlled diet and consuming alum-treated drinking water.
Results showed that there was no significant detectable increase in the concentration of aluminium in the blood of volunteers after consuming food or alum-treated drinking water. Age and gender made no difference to the amount of aluminium absorbed from drinking water.
"The results were able to establish that the way the human body copes with aluminium from food and water is similar. This means that aluminium from alum-treated drinking water is not uniquely bioavailable and is therefore unlikely to contribute to Alzheimer's Disease," Dr. Stauber says.
"Our results indicate that water authorities can confidently continue to use alum to treat drinking water with minimal risk to human health," Dr. Stauber says.
The study into drinking water was supported by a related report identifying sources of aluminium in the Australian diet (see attachment for details). This study was undertaken by Dr. Fiona Cumming of the Australia New Zealand Food Authority and Ms. Jane Allen of Deakin University on behalf of WSAA.
The report found that the average amounts of aluminium that Australians consume through food and beverages were well within the safe limit established by the Food and Agriculture Organisation/World Health Organisation Joint Expert Committee on Food Additives (JECFA).
More Information:
Maria Knox 0418 483 559 mobile or (02) 9490 8814 (bh), (02) 9516 2168 (ah)
Dr. Jenny Stauber, CSIRO Energy Technology
(02) 9710 6808(bh) (02) 9543 2199(ah)
email: Jenny.Stauber@det.csiro.au
or Dr. John Langford, Water Services Association of Australia
mobile 0419 321 350, (03) 9606 0678 fax 03 9606 0376
email: info@wsaa.asn.au
Australians' Aluminium Intake Within Safe Limits
A report titled 'Aluminium in Food and Water: An Australian Perspective' was commissioned by the Water Services Association of Australia (WSAA) and produced by Ms Jane Allen of Deakin University and Dr Fiona Cumming of the Australia New Zealand Food Authority. The report provides the first real database of sources of aluminium in the Australian diet.
Australian's intake of aluminium from food and beverages is well within the safe limit established by the Food and Agriculture Organisation/World Health Organisation Joint Expert Committee on Food Additives (JECFA).
The report shows that average Australian adults consume around 0.6 milligrams per Kg body weight of aluminium per week, while average adolescents and children consume between 0.6 & 1.4 milligrams per Kg body weight per week.
This is well under JECFA's recommended tolerable weekly intake of 7 milligrams per Kg body weight for all age groups.
Main contributors to aluminium intake for both males and females were tea and some cereal-based processed foods.
Reports from overseas indicate that it is largely the processed rather than fresh food items that are the main contributors to total dietary aluminium intake.
The report also provides food composition information for people wanting to manage their aluminium intake.
More information:
Dr. Fiona Cumming Australia New Zealand Food Authority
bh (02) 6271 2614 & mobile 0418 476 234
Dr. John Langford, Water Services Association of Australia
(03) 9606 0678 fax 03 9606 0376 , mobile 0419 321 350
email: info@wsaa.asn.au