Millions of tonnes of dangerous substances are being used unsafely in consumer and other products and getting into the environment.
Officials have been urged to step up efforts to regulate chemicals which could pose a risk to human health and the environment.
EU governments have not taken action on dozens of substances found to be unsafe, according to a new report by the European Environmental Bureau (EEB).
The group, which represents around 150 environmental organisations, has also called for regulation to be sped up and more checks to be carried out.
Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) - an EU regulatory process - was set up to protect health and the environment by identifying the properties of chemical substances.
National authorities, including the UK, began substance evaluations in March 2012.
A group of 352 suspected of being potentially harmful were prioritised for evaluation by the end of December 2018.
By this point, safety checks had been completed on 94 substances, 46 of which were declared to pose a possible risk to human health or the environment, according to the EEB report.
In 34 out of the 46 cases highlighted, the European Chemicals Agency (ECHA) received no plan to manage the risk from the EU member state.
Proposed action could include implementing a ban or improving labelling.
Jeremy Wates, secretary general of the EEB, described the numbers as "stark" and urged officials to "raise their game".
"The analysis documented here reveals that progress is far slower than expected or hoped and a startling proportion of problem substances remain uncontrolled," he said.
Tatiana Santos, EEB chemicals policy manager, called for officials to make chemical safety a "much higher priority".
"Millions of tonnes of dangerous substances are being used unsafely in consumer and other products and getting into the environment," she said.
"It can take over a decade for officials to protect us, largely because companies fail to provide sufficient safety information.
"Is it really too much to expect good data from an industry worth £500 billion a year in Europe? It claims safety is a priority. The facts suggest it is not."
Professor Sir Colin Berry, emeritus Professor of Pathology at Queen Mary University of London, warned chemical testing is a "long and complex process".
"Looking at the sorts of things that are now being tested, I'm not concerned that they are a real problem in terms of human health," he added.
"I think there are problems environmentally, from the disposal of chemicals, but that's a different set of problems which I think has to be managed in a quite different way."
The ECHA said an action plan aimed at increasing the number of checks and accelerating its work was due later this year.
"We agree on the need to speed up and encourage member states to find enough resources to do the work and follow-up on substance evaluation findings through risk management measures," it said in a statement.
"Our strategic plan for 2019-2023 focuses on ensuring efficient and effective use of the EU chemicals legislation.
"The core of our work for the coming years is data generation and regulating substances of concern to improve the safe use of chemicals."
Sally Wardle is the health and science correspondent for Press Association.