Now I'm really confused about this plastic drinking bottle thing. Read what the Toronto Star had to say about it today:

"Bisphenol tied to lower brain function Plastic-bottle chemical may alter neurological links required for learning and memory, study finds"

Prolonged exposure to bisphenol A, a controversial chemical commonly found in plastic bottles and food containers, may affect the brain's ability to create neurological connections needed for learning and memory, researchers say.

A study in the Proceedings of the National Academy of Sciences found that low doses of bisphenol A impaired the creation of synapses in the brain, affecting neurons' ability to communicate.

"The ability of the brain to remain plastic and to respond to things by changing its connection is a critical part of brain function, it's important for learning and memory, it's important for mood swings, for depression," said Neil MacLusky, a biomedical professor at the University of Guelph. "It dramatically impairs the formation of synapses in the regions of the brain where such processes take place."

The use of bisphenol A in plastic bottles, baby bottles and plastic toys came under scrutiny a few months ago, after Health Canada found it to be dangerous to babies and the environment.

But this study focuses on the effect of bisphenol A on adults. The researchers exposed African green monkeys to a daily dose of 50 micrograms per kilogram, an amount declared safe for humans by the U.S. Environmental Protection Agency, over a month-long period.

"This is the very first study to look at a primate exposure over a long period of time," said MacLusky. "One of the biggest surprises of the study is how powerful bisphenol A is."

In the study, synaptic activity was diminished when bisphenol A was introduced in primates, who were also given estrogen, a hormone that normally boosts synaptic processes. Even at low levels, bisphenol A reduced the density of synaptic activity taking place in the brain.

Although the actual exposure of humans in Canada is "much lower than the daily amount," the study is a reminder of the implications of continuous exposure.

"What is the effect of having this around for your whole life? We don't know that yet," MacLusky said. "Governments should really be looking more carefully at what the safe daily limits are, and it is probably wise to not include bisphenol A in things that people are going to eat from and drink from."

In April, Health Canada announced it would work to ban plastic baby bottles with the chemical.