Algae Poses No Threat To Milk

January 28, 2000 The Rural news

Canberra — Milk remains safe for human consumption even if dairy cattle drink water polluted by toxic blue-green algae, the CSIRO has found.

CSIRO Land and Water's Dr Gary Jones said the toxins did not get into their milk. "Many rural water bodies, including farm dams, can be affected by blooms of blue-green algae which can produce a variety of potentially fatal toxins," Dr Jones said in a statement.

He said it was not uncommon for livestock to drink non-lethal doses of algae from these dams, which raised the question of whether the toxins could contaminate our "clean green" agricultural products and present a health risk. This possibility was raised in a report to the Prime Minister's Science and Engineering Council in 1996.

But research by scientists from CSIRO Land and Water and CSIRO Tropical Agriculture found little risk of the algal toxins contaminating Australian dairy products. Land and Water's Phillip Orr said the research was intended to find out whether one particular toxin could get into dairy products, especially milk.

"The good news is that it can't," Mr Orr said.

To test the theory dairy cows were fed water contaminated with a typical bloom concentration of the blue-green algae microcystis. This produced a potent toxin known as microcystin that can cause liver damage and cancer if consumed in sufficient amounts. The World Health Organisation recently advised an absolute limit of one part per billion of microcystin in human drinking water.

"Not only did the cows themselves show no ill effects from drinking this contaminated water, but we could not even detect trace amounts of microcystin in their milk using two highly-sensitive tests" Mr Orr said.

Tropical Agriculture's Dr Bob Hunter said the findings were reassuring for the dairy industry and for consumers. "We consider it to be good evidence that cows which have consumed water or feed contaminated with microcystin produce milk which is either free of the toxin or has levels so low that it presents no threat to our health," Dr Hunter said,