“No need ever to wear shoes in our resort,” says the ad for an idyllic, upscale, family-friendly tropical beach resort.

Alas, if only true! Footwear - plus other precautions - is essential at all beaches, at home and in the tropics, with tropical beaches requiring some extra precautions.

Call it sand pollution. Researchers have known about it for years, but there have been few studies. While most health departments test swimming water for disease-causing microorganisms and ban access when pollution becomes excessive, sand is rarely monitored and access to sand is almost never restricted.

Beach sand can harbor as many types of disease-causing microorganisms and in similar concentrations as adjacent swimming water. So says the Environmental Protection Agency (EPA). There is a positive relationship between sand exposure and intestinal illnesses. Wet sand is more likely to cause illness than dry sand; it contains more water.

Fortunately, in temperate climates, most sand-related illnesses are more annoying than alarming. Families should watch their steps on beaches (literally and figuratively), but there is no need to discourage families from going, says the EPA.

Sand-related activities determine possible illnesses. Walking in sand can cause foot injuries. Intestinal illnesses are more commonly associated with (in order of increasing frequency) lying on the sand, digging in the sand, and being buried in the sand. Young children are particularly at risk. They place their hands in their mouths, eat food items that they drop in the sand, rarely wash their hands, and are particularly susceptible to intestinal illnesses. Skin, eye, ear, nose and respiratory infections also increase with sand contact. However, most of these illnesses, too, are not severe, and the mode of transmission is often not obvious.

Particular situations increase the risk of illness. Look for sand spots far from sewer outlets, especially in the days after major rainstorms. Heavy rainstorms can overwhelm the local sewage plantbs ability to treat wastewater, resulting in raw sewage flowing into the water and polluting the sand. Some microorganisms survive longer in sand than in water. Choose spots away from birds and animals; their feces contain many disease-causing organisms.

Take precautions to reduce the likelihood of illnesses. Read postings about local hazards. Dress children in appropriate footwear (see below). Wash their hands frequently. Have them lie on beach chairs or, at least, on blankets over the sand. Teach children not to touch strange objects on the beach or in the water, even if the objects appear harmless. Carry and use hand sanitizers.

Insist that children wear appropriate footwear. Walking barefoot in the sand or wading in the water can be the first leg of a trip to the first aid station or ER. Common injuries include bruises, stubbed toes, lacerations, puncture wounds, and burns from hot sand or pavement. Choose well-ventilated, hard-soled footwear that covers toes, is lightweight and easily slips on and off. Dozens of types are advertised on the web (search for “beach footwear”).

Tropical beaches are especially troublesome. Sandy sea bottoms conceal poisonous sea life that may have tentacles, fangs, barbs, spines, or stinging cells that can inject venom into human intruders. Poisonous sea life can resemble rocks or seaweed. Jellyfish blend into their background and their tentacles can extend many feet. Coral is a live organism with sharp edges that can lacerate skin. Grains of coral may enter wounds, causing infection. Some coral produces venom, further aggravating the injury.

Treating tropical beach injuries requires expertise. Injuries caused by different forms of sea life call for different treatments, and the wrong treatment can worsen the problem. Moreover, many people, especially children, are unaware of what injured them. Waterfront personnel can be helpful in suggesting appropriate treatment. Seek expert medical care if the injured person shows shock-like symptoms (paleness and difficulty breathing, for example).

Playground sandboxes also can be sources of illness. Sandboxes attract small animals. They should be covered when not in use, checked for microorganisms periodically, and the sand should be changed from time to time. Very often, none of these are done. Many playgrounds have eliminated sandboxes as being too troublesome.