<prompt> A pregnant lady uses fluoridated drinking water. All of the following are true regarding exposure of the foetus to fluoride except:The placenta acts as a regulator and reduces the concentration of fluorides reaching the foetusThe placenta acts as a regulator and increases the concentration of fluorides reaching the foetusBothNone  <response>: There are different views regarding the passage of fluoride across the placenta.Some authors have said that placenta acts as a complete barrier to fluoride, others have said that it is only partial. Some have said that the placenta only acts as a barrier when there is a sudden increase in the maternal plasma fluoride level.Essentials of preventive and community dentistry Soben Peter 5th edition 