Sunday November 12 2:49 PM ET Pope Warns on Biotech Health Risk By FRANCES D'EMILIO, Associated Press Writer VATICAN CITY (AP) - Dedicating Sunday to the world's farmers, Pope John Paul II urged those who are developing new biotechnologies to keep a ``healthy balance'' with nature to avoid putting people's lives at risk. Tens of thousands of farmers and their families, most of them from Italy but many from other countries and continents, crowded into St. Peter's Square on a chilly, overcast day to attend Mass celebrated by the pope on the steps of St. Peter's Basilica. The Mass was part of a Holy Year tribute to the world of agriculture. John Paul didn't cite any specific kind of biotechnology Sunday. But his words picked up on a speech he gave Saturday evening in which he urged rigorous scientific and ethical controls to avoid possible ``disaster for the health of man and the future of the Earth'' from new agricultural technologies. On Sunday, the pope told the farmers in the square that ``if the world of most refined techniques doesn't reconcile itself with the simple language of nature in a healthy balance, the life of man will run ever greater risks, of which already we are seeing worrying signs.'' John Paul didn't specify what signs he meant. The 80-year-old pope looked tired and his breathing at times sounded labored as he read his speech. Some 90 minutes into the ceremony, he consulted his watch as if growing weary of the event. When he was leaving the square, he briefly lost his balance on one of the basilica's steps. Two aides flanking him quickly grabbed on to him and the pontiff was able to continue walking down the steps to his ``popemobile.'' Hip surgery a few years ago and a chronic shuffle as he walks - a symptom of Parkinson's disease - have made it difficult for the pontiff to get around. Throughout the Holy Year called for by John Paul to mark the start of Christianity's third millennium, various fields of work have had their day at the Vatican, from politics to journalism to circuses. John Paul told the farmers Sunday to ``resist the temptations of productivity and profit that work to the detriment of the respect of nature.'' Saying God entrusted land to mankind to take care of it, the pope said: ``When you forget this principle, becoming tyrants and not custodians of the Earth, sooner or later the Earth rebels.''