I googled around a bit about the safety issues of both types of tree with a baby in the house and this is what I found...
Question: Are Christmas tree lights covered in lead and are they hazardous? I am not normally paranoid, but I just read an article on how the presents under the Christmas tree get covered in lead dust
Christine Climer replies: The wires of many electrical devices, including Christmas lights, are insulated inside a plastic (PVC) coating. Some sort of stabilizer must be added to the PVC so that it will be heat resistant. PVC stabilizers commonly include metals such as lead, cadmium and tin.
The concern with these Christmas lights is that the lead will leech out of the PVC and be deposited on your hands while you are decorating. Lights containing lead that are sold in California must carry a Proposition 65 warning label, but those sold elsewhere contain no warnings. Lights manufactured in the United States are less likely to contain lead.
Do not allow your children to handle Christmas lights. Wash your hands thoroughly after handling them yourself.
You should also be aware that those Christmas lights arent the only things to be cautious about when selecting your holiday decor. Artificial Christmas trees made of PVC also contain stabilizers.
Researchers at the Environmental Quality Institute at the University of North Carolina-Asheville have found that some PVC trees release lead dust into the air and onto the ground and presents underneath the tree. Your children can breathe the dust and contaminate their hands while touching the ground or unwrapping gifts. As we all know, lead exposure is of particular concern during childhood.
Sue