Lead based paint is a problem!!
Lead has long been known to be a significant health hazard, particularly toxic for small children. It is cumulative and among its many health concerns can cause damage to the central nervous system.
Lead was usually added in the manufacture of paints prior to the 1970 in New Zealand to help with paint drying and as a preservative.
Prior to 1945 white lead was used extensively as a pigment, but was subsequently replaced by titanium dioxide. The use of white lead was discontinued in New Zealand about 1965. Red lead was used as a primer until the 1980s.
All paint manufactured after 1980 in New Zealand has a very low level of lead. Paint manufacturing is now highly regulated.
With older houses new paint is usually just applied over the top of the existing paint, so most of these houses still have extensive areas of lead based paint.
Lead based paint is generally not a major issue if covered by newer paint. When sealed it can remain dormant indefinitely. It becomes a health hazard issue when the underlying paint is disturbed.
There are some health precautions required where lead-based paints may be present, even if the original paint has subsequently been painted over with newer paints without any lead content.
Avoid the creation of dust containing lead through dry sanding, or lead containing fumes with burning off paint from old houses without taking proper protective measures, particularly in the interior.
There is a useful government publication on lead: Guidelines for the Management of Lead-based Paint that is a free download from the Department of Health website.