Thursday, May 25, 2006

Exposure to Phthalates from Water Insignificant

News and opinion articles in the Australian media continue to suggest links between genital abnormalities and water supplies. This week its a group of chemicals called 'phthalates' towards which the finger is pointed. Lets take a closer look at the issue.

Phthalates are man-made chemicals that have been shown to have hormonal-type effects on some animals exposed to high doses in laboratory experiments. These effects include improperly formed reproductive organs, reduced sperm counts and a general decrease in mating, pregnancy and fertility.

Scientists reasonably suspect that similar effects may be possible for humans exposed to sufficient doses. However, very little is currently known about human health effects. Direct links between the effects observed in animals and a decline in human reproductive health have so-far been unable to be established.

These concerns make it very important for the issue to be carefully investigated and monitored. The first questions we should ask are how much are we exposed to phthalates? And what are the significant sources of exposure?

Last year an international group of experts met at a Workshop on Environment, Reproductive Health and Fertility in Copenhagen, to discuss current issues in human fertility and reproduction trends. The papers from this meeting were published in the International Journal of Andrology (Vol 29, No. 1). Phthalates were an important topic on the agenda. A number of the papers presented described the likely major sources of exposure to people.

US scientist, Dr Ted Schettler from the Science and Environmental Health Network identified a long list of consumer products which contain phthalates. These included “building materials, household furnishings, clothing, cosmetics, pharmaceuticals, nutritional supplements, medical devices, dentures, children’s toys, glow sticks, modelling clay, food packaging, automobiles, lubricants, waxes, cleaning materials and insecticides”. He did not identify drinking water among the significant sources.

A team of German scientists from the Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, also identified an extensive list of products containing phthalates. These were flooring, carpeting, roofing, vinyl wall covering, upholstery, wire and cable sheathing, clothing, packaging, toys, detergents, industrial solvents, wetting agents or lubricating oils, e.g. for lacquers, colours or adhesives. Again, drinking water supplies were not identified as a significant source.

Dr Schettlers paper states “Historically, the diet has been considered the major source of phthalate exposure in the general population, but all sources, pathways, and their relative contributions to human exposures are not well understood. Medical devices containing di-(2-ethylhexyl) phthalate are a source of significant exposure in a susceptible subpopulation of individuals. Cosmetics, personal care products, pharmaceuticals, nutritional supplements, herbal remedies and insecticides, may result in significant but poorly quantified human exposures to dibutyl phthalate, diethyl phthalate, or dimethyl phthalate”.

Since phthalates are known to leach from plastics, it may reasonably be assumed that bottled water (and anything consumed from a plastic container) may be a source worth investigating. However, having now reviewed all of the papers presented at this meeting, I have been unable to find any justification to reasonably assume Australian tap-water supplies to be a significant exposure source.

I have searched, but have not been able to find any data showing any Australian drinking water to contain concentrations of phthalates that could come within a bull’s roar of the much higher doses that we are exposed to from practically everything else we come into contact with.

Accordingly, current calls, by a few doctors, to revise Australian drinking water guidelines on the basis of phthalate exposure seem to me to be unfounded and alarmist. To link Sydney's drinking water supplies to a reported increase in genital abnormalities in New South Wales is utterly unscientific. Nonetheless, I am always willing to consider any alternate evidence that anyone would like to provide me with.

If a need to more carefully control phthalate exposure from drinking water is established, major drinking water recycling schemes offer a unique opportunity to do this. Only advanced treatment processes such as reverse osmosis and advanced oxidation are able to significantly remove these compounds. It is unrealistic to expect that these expensive and energy-intensive processes will be routinely employed for conventional drinking water sources. However, planned drinking-water recycling schemes provide a strong justification for their use.

Promoting fear about chemical exposures from recycled water seems to be an increasingly popular pastime in Australia. However, perhaps it makes more sense to see water recycling as an opportunity to actually decrease our exposure to hazardous chemicals.

Tell me what you think.



Anonymous said...

Fair enough that water may not be a significant source, but the information in this blog-entry is pretty darn scary anyhow!!

iwtfmb said...

great blog stuart. i appreciate your effort to stick to the facts rather than overstating the claimed benefits of reycling, worldwide experience with recycling or the ability of the so many other proponents seem to do! i hope you can keep it going.

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