WASHINGTON (AP) - Tobacco companies will be required to report

the levels of dangerous chemicals found in cigarettes, chew and

other products under the latest rules designed to tighten

regulation of the tobacco industry.

     The preliminary guidance issued Friday by the Food and Drug

Administration marks the first time tobacco makers will be required

to report quantities of 20 chemicals associated with cancer, lung

disease and other health problems. The FDA will require companies

to display the information in a consumer-friendly format by next

April.

     Constituents or byproducts of tobacco products that are subject

to the new rule include ammonia, carbon monoxide and formaldehyde.

     Regulators have identified more than 93 harmful or potentially

harmful chemicals in tobacco products, though the agency is only

focusing on 20 for the coming year. The agency will take comments

on the guidance until June 4, before finalizing them.

     A law enacted in 2009 gave the FDA authority to regulate a

number of aspects of tobacco marketing and manufacturing, though

the agency cannot ban nicotine. The same law lets the agency

approve ones that could be marketed as safer than what's currently

for sale.

     In separate guidance issued Friday, the FDA laid out the

scientific studies it will require before any company can market a

so-called modified-risk tobacco product. Companies must submit

extensive testing data on health risks, user behavior and consumer

understanding of marketing materials for new products.

     "The law sets a high standard to make sure that tobacco

products marketed to reduce risk actually reduce risk," Dr.

Lawrence Deyton, director of FDA's tobacco center, told reporters

on a conference call.

     The FDA's handling of modified-risk products has been highly

anticipated by both the public health community and bigger tobacco

companies, which are looking for new products to sell as they face

declining cigarette demand due to tax increases, health concerns,

smoking bans and social stigma.

     Some tobacco companies have alternatives like snus - small

pouches like tea bags that users stick between the cheek and gum -

and dissolving tobacco - finely milled tobacco shaped into orbs,

sticks and strips. But they are not explicitly marketed as less

risky than cigarettes.

     Industry experts expect it will take the FDA a year or more to

review applications for modified risk products.