Q.I can't help but notice the red blemish on Mr. Gorbachev's forehead. Do you know what caused it? Is it a sign of any other condition?

A.The Soviet leader has a birthmark on his forehead called a port wine stain. Named for its red-wine color, this skin blemish usually is present from birth, most often affecting the face or arms. It is caused by a malformation of blood vessels and appears either as a flat or pebbly patch of purplish-red skin.

Port wine stains usually last for life, although they may fade a little.

Until recently, there was no good treatment for this type of birthmark, except for wearing a masking make-up like Covermark.

Now, various laser techniques -- the newest being the "tunable" laser -- use special wavelengths of light to obliterate the abnormal blood vessels, leaving a more natural-looking skin surface. But even laser therapy is often unsatisfactory, and in most cases it may be best to get along without any treatment.

Most of the time, port wine stains are simple birthmarks and not a sign of any other abnormality. Occasionally, port wine stains on the face are accompanied by malformations of blood vessels in the brain -- a serious condition known as Sturge-Weber syndrome that can cause mental retardation, blindness, strokes and seizures.

Port wine stains are somewhat different from a related birthmark known as strawberry hemangiomas (blood vessel growths). Named for their raised, bumpy, dark red appearance, these birthmarks generally get larger during the first six to 12 months of life. After that, they gradually clear, usually from the center outward. Most disappear in early childhood, so treatment -- with surgery or lasers -- is usually not needed.

Q.As a baby-sitter, I've observed many young children brushing their teeth before going to bed. I'm alarmed at the number who swallow toothpaste after brushing rather than rinsing out their mouth.

In fact, one child cried and was upset because I tried to make him rinse after brushing.

Are there any risks to children who regularly swallow toothpaste?

A.There are some risks to young children from swallowing toothpaste, so it's important that they be taught how to brush their teeth properly and be supervised until they know how to do it right.

Fluoride is the main potentially harmful ingredient in toothpaste. Different problems can develop depending on whether a young child swallows a lot of toothpaste at one time, or swallows small amounts over longer periods.

A single large dose of fluoride toothpaste -- such as eating a whole tube -- can be harmful. A 9-ounce tube contains about 255 milligrams of fluoride.

The potentially lethal dose of fluoride is about 11 milligrams per pound of body weight. For the average 2-year-old (weighing 27 pounds), that's about 300 milligrams, not much more than in a 9-ounce tube.

Fortunately, other ingredients in toothpaste are irritating to the stomach, and eating any significant amount of toothpaste would cause a child to vomit, largely eliminating the risk of serious fluoride poisoning.

In addition, the National Capital Poison Control Center at Georgetown University reports that most toddlers who accidentally eat toothpaste don't ingest more than 1 ounce at a time. One-time ingestions, therefore, have a high margin of safety.

The situation is different with children who regularly swallow small amounts of toothpaste, similar to what you've described. Although there's no immediate danger, long-term ingestion of fluoride toothpaste can lead to fluorosis -- a permanent yellow-brown discoloration of the teeth.

Swallowing even small amounts of toothpaste regularly can double a child's fluoride intake (especially if water is already fluoridated, as it is in the District of Columbia metropolitan area).

An increase of two to three times the recommended fluoride dosage for children -- 1 milligram daily between 3 and 14 years of age -- can cause permanent tooth discoloration. Thus, the margin of safety for swallowing toothpaste day after day is low.

New, "extra-strength" fluoride toothpastes are being introduced onto the market. The higher concentration of fluoride increases slightly the risk of fluoride toxicity while providing no clear benefit, and I don't recommend these products for young children.

To develop good teeth-brushing habits in young children, have them use a small amount of toothpaste under your direct supervision, and teach them not to swallow it.

Jay Siwek, a family physician from Georgetown University, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington.

Consultation is a health education column and is not a substitute for medical advice from your physician. Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Questions cannot be answered individually.