Of the 60 kindergartens that volunteered for testing, two-thirds showed high levels of phthalates, a type of plasticizer that can cause endocrine system disruption, environmental group Friends of the Earth Germany (BUND) said in Berlin.
The chemicals, used in countless plastic products worldwide, can change hormone levels, causing sterility, birth defects, and increasing the risk of breast and testicular cancer, the group said.
Children are particularly vulnerable to phthalates because their organs have not fully developed.
The high concentration in care centres for children seems to arise from their abundant use of plastic products, including PVC flooring, tumbling mats, balance balls and toys.
BUND analyzed dust at each of the facilities, finding that the phthalates DEHP and DINP were most common.
The Federal Environment Agency (UBA) generally discourages the use of phthalates, in particular DEHP, in toys, a practice that has been restricted in the European Union since 1999. The 2008 the United States also banned the use of more than 0.1 percent of certain phthalates in children's toys.
Phthalates and other plasticizers are mixed with synthetic materials to improve flexibility and durability, and some products contain up to 50 percent of the substance. According to BUND, one million tonnes of phthalates are produces in Western Europe annually.
Used in a variety of products, from cosmetics to building materials, the chemical does not bond to other materials, thus it is released into the environment as plastics break down. While this poses no problem outdoors, where they biodegrade, they accumulate indoors, increasing the risk of exposure.