Did you know that most glazes on items (even food-use items for humans) IF they are made in non-USA countries, have lead in them? If they are made in the USA, they have to be made with a lead-free glaze. If they are made in foreign countries, they can have lead in the glaze. China and India are the biggest offenders.
My mom worked for the Oregon state government lead program, and the biggest offenders for household items made with lead are paint from pre-1978, household dust in houses built before 1978, water from household lead pipes, crystal and leaded glass, made-in-China porcelain and ceramic glazes, window blinds, Christmas lights that are not made in the USA, and crayons and paints made in China and India.
The US has strict laws on lead levels for most products IF they are made here. Window blinds, food/water bowls, and household dust are the main threats for cats (and dogs, and human babies). Do not let your cats lick or bite the window blinds if you have anything except for wood blinds. Have your tap water tested for lead (there is a home test for this, contact your government office), and if there is lead you can get a filter. If unsure of the lead content of your water, use cold water or filter your water. Wet-mop or wet-wipe surfaces such as the floor, counters, and window ledges frequently to prevent dust buildup in pre-1978 houses. If there is peeling paint, paint over it (most house paint is layered, and there can be lead paint under the newer layers in pre-1978 houses).