Integrating a 3rd party service into site that is setting google analytic cookies

Hi,

Im integrating a 3rd party service into my site that loads stuff using JS into the page.

What concerns me is that it is setting the _ga cookie along with _utm* value from its domain. The _Ga cookie is the same value as the one set on our site.

How can I be sure that they are not tracking and reporting our users data to themselves?

Any help would be much appreciated

Thanks

For example now Ive put in the twitter JS, twitter is now storing cookies under their domain for _GA and all the _UTM cookies