my @combined = ();
my ($col1, $col2, $col3, $col4) = '';

while (@array1) {
$col1 = shift @array1; chomp $col1; $col1=~s/,/\,/g; #escape commas
$col2 = shift @array2; chomp $col2; $col2=~s/,/\,/g;
$col3 = shift @array3; chomp $col3; $col3=~s/,/\,/g;
$col4 = shift @array4; chomp $col4; $col4=~s/,/\,/g;

push @combined, "$col1,$col2,$col3,$col4\n";
}

open OUTPUT, ">$target_file" or die "Cannot open target file!  $! \n\n";
print OUTPUT @combined;
close OUTPUT;