The 28 April London conference heard Campbell respond to three researchers who discussed neonicotinoid damage to bees.
Campbell said there were "multiple threats to pollinators" and that beekeepers say diseases such as varroa are the number one threat, rather than chemicals.
He added: "We have done a lot in the industry to improve this aspect of pollinator health through risk reduction measures and there has been a massive reduction in bee poisioning incidents."
He said laboratory versus field experiments were not reliable indicators of damage to bees, adding: "Beware of studies using forced exposure."
Campbell said presence of residue does not mean there is a risk and that there is no evidence of accumulation.
Professor Dave Goulson had outlined his research that found mixtures of neonicotinoids and other pesticides are found in the pollen and the nectar of wildflowers growing in arable field margins and hedgerow flowers like hawthorn, wild rose, blackberries and honeysuckle at concentrations that are sometimes much higher than those found in the crop.
The EU stopped three neonicotinoids from being used in 2013 (imidacloprid, thiamethoxam and clothianidin) but the UK and some other nations have since allowed emergency use on oil seed rape.
Campbell said "correlation is not causation" adding that "contamination is very easy" and that he could understand how the concentrations could be higher in wild plants.
He said "habitat is one of the key issues to make a difference to pollinator health" and called for more support for wildflower margins, concluding: "Is there not more scope to work together on what we can agree will improve pollinator health instead of arguing abut what which divides us?"