Ralph Nader's Health Research Group (HRG) asked yesterday that all the remaining synthetic dyes made from coal tars be banned from the food supply immediately.

The Washington-based group said there is evidence that some of the nine dyes used to color orange skines, sofr drinks, ice cream, hot dog casings, and bakery products cause cancer and there is at least "suggestive evidence" that others are carcinogenic.

In a petition filed with the Food and Drug Administration, HRG said children are particularly vulnerable to these artificial colors since some of them "eat as much as one quarter pound of coal tar dye each year."

A spolesman for FDA said the search group "is overstating the issue and causing public alarm that is simply not warranted."

Coal tar dyes, in use since the 1800s, belong to "a suspect family of chemicals, some of whose members have beeb banned by the FDA for their ability to cause cancer . . .," according to the petition. These include Red No. 2, once the most widely used artficial color, and Red No. 4, both of which were banned last year.

A 1960 law required that all food dyes be proved safe. The law said dyes could be marked for 2 1/2 years or longer until safety studies were completed. Between 1963 and 1971, FDA permanently approved six of the coal tar dyes; the other three are still provisionally approved. According to HRG, which examined FDA's data, the tests either are inadequate to prove safety or actually prove the dyes are carcinogenic.

One of the nine dyes cited by HRG, Yellow No. 5, which is the most widely used food color in the country, is known to cause serious allergic reactions in humans. FDA said yesterday it will soon require that Yellow No. 5 be listed on labels by name because many people are allergic to it.

HRG said Red No. 40, the second most widely used artificial color, is shown in current tests to cause cancer in animals. An FDA spokesman said yesterday agency scientists will act on the testing data "as fast as law and science will allow them."

The other approved coal tar dyes are Citrus Red 2, used to color some Florida oranges; Orange B, which colors hot dog and sausage csings; Red No. 3 and Yellow No. 6 are provisionally approved.

The research group also asked FDA to review 23 non-coal tar dyes like caramel. HRG said there is little information in agency files on these color additives to either prove or disprove their safety.