Particle board contains formaldehyde typically which does offgas. It depends if IKEA offgases this in the manufacturing process or not.
Lacquer contains Volatile Organic Compounds (VOCs) which offgas more than particle board typically.
Plastic laminate can be used to seal in these chemicals so long as it is properly done and all edges are sealed. As soon as the laminate starts to degrade or delaminate, the seal is broken though. Laminate itself is pretty inert and most are Greengaurd certified because they themselves do not offgas, but it depends on the company.
For more information:
Read "Is there a finish I can use to seal MDF surfaces on a changing table for my baby's nursery?" a Q&A answered by Debbie Sek.