We take safety and sustainability seriously. It was important to us that the blocks also be durable and of lasting quality. These blocks are designed from durable and sustainable hardwoods, finished with safe plastic fittings. We work closely with all our suppliers to ensure safety is a top priority, from design through finishing. Zenius toys comply with the criteria set forth by independent testing agencies who have verified our compliance with the applicable federal regulations. See our CPC here and test results here.