Can anyone tell me if there is a limit to the amount of tinned tuna kids can eat "safely"? DDs (aged 4 and 2) insist on having a tuna mayonnaise sandwich/pitta every lunchtime (and would eat the same for tea if I let them!) I read somewhere about limiting the amount of tuna but I think that was for fresh tuna (?) and possibly in relation to pregnant women. Can anyone put me straight?