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Fast Fact

One of the great wonders of the human body is the ability of damaged cells to be repaired or replaced. Red blood cells, for instance, live for about 120 days. Each day, about 1% of your red blood cells retire to be replaced by a fresh generation. The lens of the eye is a notable exception. The cells of the lens of the eye are never replaced; the proteins of the lens are never replenished. The lens cannot repair itself; damage accumulates over a lifetime.
Cataracts are the result of gradually accumulating damage to the proteins of the lens. The most important source of this damage is exposure to ultraviolet (UV) radiation, especially while one is young.
Behind the lens lies the retina, the thin lining of the back of the eye. The retina is the eye's miracle. This patch of tissue, about the size and thickness of a postage stamp, is able to dissolve and create a new image every tenth of a second.
Today in the United States, retinal diseases are the leading cause of blindness. Macular degeneration, the accumulation of damage in the retina, is the leading cause of blindness from retinal disease. Slowly, over the years, the macula is irreversibly damaged by exposure to UV radiation. About one third of adults over age 65 experience this steady decline of central vision, not correctable by glasses.
Excessive exposure to sunlight during early childhood is harmful to the eyes. Sunlight contains harmful UV radiation.
The risk for retinal damage from the sun's rays is greatest in children less than 10 years old, although the consequences usually do not become apparent until well after they are adults.
All children should be taught to wear sunglasses, especially between 10 AM and 2 PM, when ultraviolet exposure is the most dangerous. This is true even for children with darker eye colors, even though their darker pigments afford partial protection. Of course, children with light-colored eyes need sunglasses all the more.
Ultraviolet exposure is at its peak when children are at high altitudes, snow-covered landscapes, bright sandy beaches, or near reflective bodies of water.
All sunglasses are not the same. Effective sunglasses should block both UVA and UVB radiation. The sunglasses must be measured to block 99% to 100% of UVA or UV400 (400 nm is the wavelength of UVA radiation). Thankfully, all sunglasses block UVB radiation.
Large lenses that fit close to the eyes are best. Those that block visible blue light are even safer.
Expensive brand names and polarizing lenses are no guarantee.
Ordinary sunglasses make the situation WORSE! The dark lenses cause the pupils to dilate, allowing more of the dangerous UVA radiation to damage the lens and the retina.

see Fast Facts about Sun and our Eyes »

Infant Botulism

10.24.2002 Add new comment Send to friend Print this article

Related concepts:

Botulism

Introduction to infant botulism:

Sometimes constipation and slow feeding are the only symptoms of infant botulism, a disease that is sometimes caused by honey.

What is infant botulism?

The honey story is fascinating. The safety concern about honey arose because honey often contains spores that, under the right circumstances, can cause a disease discovered in 1976, called infant botulism. Infant botulism is spread by these spores, not by pre-formed botulinum toxin (BoTox).

Botulism spores are found throughout nature – in soil, in dust, and on the unwashed surfaces of unpeeled fruits and vegetables. The spores are present in about 10 percent of the samples of honey tested. These spores are tough to kill. They are quite heat-resistant; some can survive boiling for several hours.

Babies’ intestines are an ideal environment for the spores. When babies swallow them, the spores can turn into growing, multiplying bacteria that pump out a poison called botulinus toxin. This toxin is absorbed through their immature intestines and causes infant botulism. Some cases of infant botulism are mild, but some are fatal.

Who gets infant botulism?

The peak age at which babies are susceptible is when they are 2 to 4 months old. They may be at risk from about 1 week until 9 to 11 months. This is the reason babies under one year old should not be fed honey. Because the spores are so heat-resistant, there is a theoretical risk for babies eating even processed foods containing honey. Commercial canning, however, usually destroys the spores. While honey is the most common single food associated with infant botulism, in most cases of infant botulism, the source is not identified.

Normally, swallowing spores is not a problem for healthy adults or older children. The spores usually remain spores. The bacteria do not grow well in mature intestines teeming with beneficial bacteria. Pregnant women, other adults, and older children are routinely exposed to spores without being affected.

Adults can get botulism from other sources, including getting the toxin directly through food or into wounds. The pre-formed toxin can be found in improperly canned or processed foods. The botulinus toxin is among the most lethal of all naturally occurring substances. Ingesting a trace amount can be deadly. Thankfully, toxin production can be prevented with proper refrigeration, freezing, drying, or adding the correct amounts of salt, sugar, or sodium nitrate. The toxin can be destroyed by heat (20 minutes at 176 degrees or 10 minutes at 196 degrees). It can even be harnessed -- BoTox is in vogue to reduce wrinkles.

What are the symptoms of infant botulism?

Usually infant botulism begins with a slowing down of the intestines, which results in constipation. This can progress to include slow feeding. Breastfeeding mothers often report feeling engorged.

Other classic symptoms include listlessness, weakness, and floppiness. The legs may flop open in a frog-leg position. Sometimes babies look so weak and lethargic that infant botulism is mistaken for meningitis.

The disease is a temporary partial paralysis that moves down the body.