Is mineral buildup on Vicks warm mist humidifier dangerous?

[Owachi]

We have to Vicks warmmist humidifiers we only use when our twins are sick....but there is a hard brown buildup on the heating element which I cannot get off......I'm not sure if it is mineral buildup or from some vicks inhalent falling onto it (because it is impossible to pour in the small hole)....has anyone else had this problem and is the humidifer safe to use or should I just throw it out? I can't find anything on the internet about it....

[annettemarie]

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