WASHINGTON — Further decreases in the trans fat content of foods is possible without the “extreme, unprecedented and unnecessary” approach of banning the use of partially hydrogenated oils, according to a March 7 letter sent by the American Bakers Association to the Food and Drug Administration.

The F.D.A. in a Nov. 8, 2013, Federal Register notice said it tentatively had determined that partially hydrogenated oils (P.H.O.s) are no longer Generally Recognized As Safe (GRAS) because they are the primary dietary source of industrially-produced trans fat. If finalized, the F.D.A.’s proposed rule would mean food manufacturers no longer would be permitted to sell partially hydrogenated oils, either directly or as ingredients in another food product, without prior F.D.A. approval.

The A.B.A. responded to the F.D.A.’s request for comment through the March 7 letter signed by Lee Sanders, senior vice-president of government relations and public affairs.

“We believe that reducing consumption of trans fat in the U.S. population is an important public health goal, and A.B.A. members’ voluntary efforts have resulted in extremely low levels of industrially-produced trans fat in finished products — lower than the levels presented by F.D.A. in its tentative determination,” she said. “Consequently, consumption of trans fat in the U.S. has dramatically decreased and will continue to decrease as industry continues to develop alternatives for the remaining few, but difficult to replace, sources of trans fat.

“Withdrawing the GRAS status of one source of trans fat, therefore, is an extreme, unprecedented and unnecessary approach and sets an unlawful standard for withdrawing the GRAS status of ingredients.”

The A.B.A. said it found several flaws in the F.D.A.’s tentative determination.

According to the A.B.A. the determination is at odds with the World Health Organization, Health Canada and other countries’ trans fat policies in two significant ways. First, their polices are directed at all sources of trans fat rather than at a single source of trans fat. Second, Canada and several other countries that follow the W.H.O. recommendations have socialized medicine health care systems and still do not recommend a complete ban on partially hydrogenated oils or trans fat.

To enforce the rule, the F.D.A. would need to provide standard methods for determining whether a substance is a partially hydrogenated oil, according to the A.B.A. The Washington-based association proposes that partially hydrogenated oils be defined as an oil produced using hydrogenation processing of the base oil to an Iodine Value (IV) of 5.1 or more.

The F.D.A. also needs to prove why it no longer believes partially hydrogenated oils are GRAS after recognizing their GRAS status for decades, according to the A.B.A.

“Given the historical safe use of P.H.O.s, F.D.A. bears the burden of demonstrating P.H.O.s are no longer GRAS based on the consumption levels in today’s diet,” Ms. Sanders said.

No other country comparable to the United States has taken a zero tolerance approach to partially hydrogenated oils or to trans fat, according to the A.B.A.

The A.B.A. proposed several alternatives to the banning of partially hydrogenated oils. The F.D.A. could change the rounding rule for declaration of trans fat on the Nutrition Facts panel to less than 0.2 grams per serving from less than 0.5 grams per serving. Currently, if a product has less than 0.5 grams of trans fat per serving, the F.D.A. mandates the level must be rounded down to 0 grams.

For another alternative, the F.D.A. could revisit the value of adding a statement to the Nutrition Facts panel recommending that consumers limit their intake of trans fat (and saturated fat). Also, the F.D.A. could declare certain uses of partially hydrogenated oils as GRAS. Some partially hydrogenated oils contribute only trace amounts of trans fat to the finished food product, according to the A.B.A.

“F.D.A.’s tentative determination that P.H.O.s are not GRAS for any use is overly broad,” Ms. Sanders said.

Both the F.D.A. and A.B.A. agree trans fat intake has decreased since 2003, but they differ on how much it has decreased.

The F.D.A. in July 2003 estimated the mean adult intake of trans fat from products containing partially hydrogenated oils was 4.6 grams per day. The F.D.A. recently estimated the mean dietary intake of industrially-produced trans fat has decreased significantly to about 1 gram per day, or 0.5% of total energy intake. The F.D.A. concluded some people still may consume high levels of trans fat, resulting in a daily intake of added trans fat of about 2.1 grams per day.

According to the A.B.A., the F.D.A. believes high-level consumers consistently would choose products with the highest levels of trans fat, including refrigerated biscuits, ready-to-use frostings, certain brands of frozen pizza and certain brands of microwave popcorn. The A.B.A. called these products “special occasion foods” that would not be consumed often.

“A.B.A. members are continuing to further reduce the use of P.H.O.s, particularly as new functional alternatives become commercially available, but certain specialty and infrequently consumed bakery products present unique challenges in trying to develop effective alternatives to P.H.O.s,” Ms. Sanders said.

The A.B.A. added the F.D.A.’s dietary intake assessment assigns a value of 0.4 grams to foods that declare 0 grams of trans fat on the label. According to the A.B.A., most reformulated bakery products use palm oil or soybean oil and typically contain less than 0.2 grams of trans fat that is from sources other than partially hydrogenated oils.

The F.D.A. pointed to possible unintended consequences resulting from the banning of partially hydrogenated oils.

Consumers may confuse partial hydrogenation with “essentially complete” hydrogenation and incorrectly believe “essentially complete” hydrogenation may contribute trans fat.

“Hydrogenation is a critical process to industry, especially to the baking industry, where solid fats are required for functionality, taste, texture, structure and shelf stability,” Ms. Sanders said.

The banning of partially hydrogenated oils might mean the loss of interesterification as a technology. Interesterificaiton produces saturated fats with precise melting characteristics and texture.

“Losing interesterification as a technology would be a great loss to industry and consumers,” Ms. Sanders said.