Ennis-Hill hoping for cleaner future but 'more to be done'
Dame Jessica Ennis-Hill remains hopeful London's World Championships will not be tarnished by doping but warned problems will not disappear overnight.
The 2012 Olympic heptathlon champion wants to see a clean summer as she prepares to collect her third World Championship gold.
Ennis-Hill is due to receive heptathlon gold from Daegu 2011 after she was upgraded from silver when Tatyana Chernova was stripped of her title last November following a doping offence.
Jo Pavey is also in line to receive a 10,000m World Championship bronze from 2007 after she moved up from fourth when Turkey's Elvan Abeylegesse retrospectively failed a doping test.
She is due to join Ennis-Hill at a special ceremony in London in August and Ennis-Hill, who retired last year, hopes others will avoid their long wait.
"We have made massive steps to becoming a cleaner sport in the past year but there's a lot that needs to be done," she said.
"You can't have that assumption that every athlete is cheating if they get on the podium because that's definitely not the case."