front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |25 |26 |27 |review

In both studies, exposure is defined by proximity to the lanfill site. The �exposure zones� are defined rather crudely. A comparison of the results shows the possible biases inherent in the ecological design. The second study used the same zones, but also made use of the distance from the subject�s residence to the perimeter of the site.