(An aside: Alright, the analytical/contrarian side of my mind immediately starts considering things like lead dust being blown out amongst the congregation, creating a sort of second-hand 'lead-ing', but no one has reported any such issue that I am aware of, so back to the point of this piece...)The problem is with the blowing - the air is pushed through the pipes by an electric blower. Here is where the Law comes in. The European Union has a set of directives (EU Directive 2002 95/EC RoHS and EU Directive 2002 96/EC WEEE) that dictate that electrical devices can have no more than 0.1 percent lead. Pipe organs have an electric blower, therefore they are electrical devices and either must be refurbished or replaced.
The other considerations my anayltical mind latched onto about the lead, its lifecycle, and impacts on the environment and human health are all reported to be non-issues. So, it all comes down to unintended consequences - at least one hopes that it was unintended. We don't have many 1,000 year old traditions in the first place and even fewer that have brought so much awe, joy, inspiration, and pleasure to the ears and hearts of so many. What would Mozart or Bach have to say about this, I wonder?
(Image source: the website of the Rieger Pipe Organ in the Christchurch Town Hall, New Zealand)