Estimates of the newborn frequency of cystic fibrosis in different Caucasian 
groups range from 4 times more to 40 times less common than the generally 
accepted figure of 1:2000. Current meconium screening trials which may be 
effective in populations with the incidence equal to or greater than 1:2000, may 
be useful for populations with an incidence as low as 1:7000 only after maximum 
improvement of the methods. Once the true incidence or the variable incidence is 
proven for Caucasian populations, screening trails in Negro, Oriental and Indian 
populations will be required.