  A celebrated result due to Wolff says if $E$ is a compact subset of ${\Bbb
R}^2$, then the Lebesgue measure of the distance set $\Delta(E)=\{|x-y|: x,y
\in E \}$ is positive if the Hausdorff dimension of $E$ is greater than
$\frac{4}{3}$. In this paper we improve the $\frac{4}{3}$ barrier by a small
exponent for Cartesian products. In higher dimensions, also in the context of
Cartesian products, we reduce Erdogan's $\frac{d}{2}+\frac{1}{3}$ exponent to
$\frac{d^2}{2d-1}$. The proof uses a combination of Fourier analysis and
additive comibinatorics.
