Herbicide manufacturer Syngenta had reservations dating back to 1970s but regulator says tighter controls, including phasing out backpack sprayers, can protect workers Follow our Australia news live blog for latest updates Get our breaking news email , free app or daily news podcast The herbicide paraquat, banned in over 70 countries, will remain legal in Australia despite Parkinson’s groups, scientists and neurologists arguing there is a strong correlation between direct exposure and the incidence of the disease. The Australian Pesticides and Veterinary Medicines Authority (APVMA) announced its final decision on Tuesday following a decades-long review of the highly toxic paraquat and a related chemical, diquat. Both are widely used in Australian agriculture.