The European Parliament has approved far-reaching legislation which will lead to the safety testing of thousands of chemicals used in everyday products.
Business has sought to weaken the law, unions to strengthen it
The law, called Reach - Registration, Evaluation and Authorisation of Chemicals - would create one database including all chemicals used in the EU.
Employers say it will impose heavy costs and cause firms to flee Europe.
MEPs also included a measure obliging firms to replace hazardous chemicals with safe ones, whenever possible.
The regulation has to be approved by national governments before it can become law, and may return to the parliament for another vote next year.
Reach in its original form would have led to about 30,000 substances - found in everything from cars to computers to children's toys - being tested for their impact on health and the environment.
It has been intensely controversial, prompting some of the biggest lobbying campaigns ever seen in Brussels, with industry on one side and unions, and health and environmental groups on the other.
REACH IN NUMBERS
1,000 pages of text already, rising potentially to 15,000
1,000 amendments voted on
30,000 chemicals to be registered over 11 years
At least one million more animal tests
Estimated costs of c 5bn euros for business over 11 years
Billions of euros saved in healthcare costs
Last week, the largest political groups in the European Parliament - the conservative European People's Party and the Socialist group - agreed on a compromise, limiting the amount of data required for substances used in volumes of less than 10 tonnes.
All of the 30,000 chemicals will still need to be registered, but up to two-thirds of them may be exempted from tests.
Instead, a new European Chemicals Agency, based in Helsinki, will decide which of these chemicals used in low volumes are risky enough to have to pass through the testing procedure.
Duty of care
Businesses wanting to use the most dangerous chemicals will have to get special authorisation from the agency.
The European Parliament also voted for improved labelling of products made with chemicals thought to be harmful.
Up to now, chemicals put on the market before 1981 - the vast majority of those currently in use - have not had to be checked for their effects on health and the environment.
The onus has been on public health authorities in individual countries to test those they suspect may be dangerous.
Reach puts the burden of proof, and a "duty of care", on business.
The tests would have to be carried out in phases over 11 years, starting with the most dangerous substances, and those used in the largest volumes.
Italian Socialist MEP Guido Sacconi, who steered Reach through the parliament's environment committee, said the vote gave Europe the "strongest protection in the world" from dangerous chemicals.
He added that "unbelievable pressure" was brought to bear on MEPs by big businesses.
Nadine Toscani, a senior policy adviser at Unice, a pro-business lobby group, said: "The legislation is going in the right direction."
But, a group of green groups, including Friends of the Earth and Greenpeace, said the MEPs had diluted the legislation too far.
"A Reach adopted on this basis will not deliver the health and environment protection the public needs, as it would leave thousands of chemicals without basic toxicity data," the groups said in a joint statement.
The European Consumers Organisation, BEUC, also said the law, as amended by parliament, would not "identify risks and hazards that need to be identified".