It is lead carbonate and yes it is toxic. You can easily remove it with a mild acid like vinegar or coke. The primary route of entry into your body is as a respirable dust so it isn't a good idea to run this though your loader that drops shot a few feet from your nose or the blast the stuff into the air.
Was there a little plastic bag packed with the shot that broke open? Let's see...lots of lead production in Peru.....hmmmmmm......coke production in Colombia....Colombia via Peru------->U.S. j/k....Rick
Call the FBI or a Haz Mat Team... it could be anthrax. Or it could be all of the above. Even if you reload it with a mask on... shooting it could also be a problem for your health and others. Good idea to clean it really well.
If there is just a little white lead carbonate on some of the shot, I would load it with care. If there is a heavy white layer on all of the shot, wash it with diluted vinegar and then wash off the shot and let it dry.
I would just tumble it with a few shots of tri-flo.. a teaspoon of graphite..and load it.. The tri-flo will stop the airborne particles in there track.. and the graphite will stick to the tri-flo recreating the old Winchester lubaloy shot.. The trick is to keep the lead oxide out of the air you are breathing..