sUrlListas = "https://www.us8.api.mailchimp.com/2.0/lists/members.json?apikey=XXXXX&id=XXX;
urlLoader2 = new URLLoader();

urlLoader2.load(new URLRequest(sUrlListas));

<cross-domain-policy>
 <site-control permitted-cross-domain-policies="all" />
 <allow-access-from domain="*" secure="false" to-ports="*"/>
</cross-domain-policy>

<cross-domain-policy>
 <allow-access-from domain="*"/>
</cross-domain-policy>