If you pin your original art please read this, it tells you exactly what the owners of Pinterest can do with your art!
"We may, in our sole discretion, permit Members to post, upload, publish, submit or transmit Member Content. By making available any Member Content through the Site, Application or Services, you hereby grant to Cold Brew Labs a worldwide, irrevocable, perpetual, non-exclusive, transferable, royalty-free license, with the right to sublicense, to use, copy, adapt, modify, distribute, license, sell, transfer, publicly display, publicly perform, transmit, stream, broadcast, access, view, and otherwise exploit such Member Content only on, through or by means of the Site, Application or Services. Cold Brew Labs does not claim any ownership rights in any such Member Content and nothing in these Terms will be deemed to restrict any rights that you may have to use and exploit any such Member Content."
They may not do anything like this but this gives them the right to do whatever they wish with your own work! They can sell, modify, adapt or sublicense your work!
If you have posted your work I would highly recommend that you take it down.
Here is the link: http://pinterest.com/about/terms/
Sharon Teal Coray