WASHINGTON — The Trump administration, after heavy lobbying by the chemical industry, is scaling back the way the federal government determines health and safety risks associated with the most dangerous chemicals on the market, documents from the Environmental Protection Agency show.

Under a law passed by Congress during the final year of the Obama administration, the E.P.A. was required for the first time to evaluate hundreds of potentially toxic chemicals and determine if they should face new restrictions, or even be removed from the market. The chemicals include many in everyday use, such as dry-cleaning solvents, paint strippers and substances used in health and beauty products like shampoos and cosmetics.

But as it moves forward reviewing the first batch of 10 chemicals, the E.P.A. has in most cases decided to exclude from its calculations any potential exposure caused by the substances’ presence in the air, the ground or water, according to more than 1,500 pages of documents released last week by the agency.

Instead, the agency will focus on possible harm caused by direct contact with a chemical in the workplace or elsewhere. The approach means that the improper disposal of chemicals — leading to the contamination of drinking water, for instance — will often not be a factor in deciding whether to restrict or ban them.