I got one and later found this so didn't use it anymore, sorry for spoiling the party :
In the 1950's various chemical compounds were added to baby products, especially those manufactured from polyvinyl chloride (PVC). Governmental regulations in England, as in the United States, had forced mattress manufacturers to add fire retardant chemicals to baby mattresses.
Antimony was approved for this purpose after PVC was found to be very flammable. Antimony is normally an extremely rare element. However, natural products such as sheepskins may contain antimony.
New Zealand sheepskins, in particular, are frequently contaminated with antimony. These sheepskins, which are commonly used by native New Zealanders known as the Maori, are therefore chemically similar to baby mattresses.
This surely accounts for the extremely high SIDS rate among this group. Antimony must be considered dangerous, because both OSHA and NIOSH have strict regulations concerning the protection of workers. Antimony has chemical properties, which make it similar to lead.
Arsenic is also a chemical and compounds containing arsenic have been added to baby mattresses. This fact deserves special attention, because it has been known that the gas of arsenic can be generated by fungal activity for over a century.
You can find the full article here
And there's more in here