Every day, the porcine shadow of H1N1 creeps closer, whether it's the nationwide shortage of the vaccine or the quarantine-worthy case that struck your friend's friend's co-worker. The swine flu, seasonal flu, and common cold each spread more easily through hand contact than by airborne transmission (coughing or sneezing). As the CDC instructs, our best line of defense against the spread of germs is vigilant hand-washing and, when that's not possible, using an alcohol-based hand rub. But all hand sanitizers are not created equal. In fact, some can do much more harm than good.

Health officials deem that a hand sanitizer is only effective if it contains at least 60% alcohol, which disinfects the skin by disrupting the metabolism of bacterial cells. Ethyl alcohol (ethanol), an anti-microbial agent that has been recommended for sanitizing hands since 1888, has a lower drying effect on the skin than other types, such as isopropyl alcohol. Nonetheless, ethanol and isopropanol alcohols are equally capable of killing microorganisms and inactivating viruses. There doesn't appear to be a mechanism whereby bacteria and other organisms can evolve resistance to alcohol.

The amount of alcohol content in a single squirt of hand sanitizer that is absorbed by the skin is comparable to drinking 1.5 ml of wine (less than a full sip). In 2007, the New England Journal of Medicine reported two cases of severe intoxication following ingestion of alcohol-based hand sanitizers. The good news is that- aside from drinking straight from the bottle- your hand sanitizer won't put you (or a child) at risk from finger licking, since the alcohol evaporates within seconds as it dries.

If alcohol isn't the enemy, what are the precise hazards that should make your hands hide in fear? To name a few, the red flags include parabens, diazolidinyl urea, triethanolamine, denatonium benzoate, and synthetic dyes (i.e. FD&C Blue 1, FD&C Red 4). Artificial fragrance, a ubiquitous sanitizer additive, is the single most common cause of contact dermatitis, and adverse reactions to this catch-all ingredient are on the rise. An Institute of Medicine report recently put fragrances in the same category as second-hand smoke for triggering asthma. Unfortunately, fragrance is hard to detect on an ingredients label since there are no regulations about disclosing it in consumer products. The healthiest alternatives are essential oils, which are naturally antimicrobial and antibacterial.

Alcohol may kill bacteria, but it doesn't necessarily clean your hands by removing organic material such as dirt, blood, and feces. It also doesn't eliminate the norovirus or E. coli very well. That's where bacteria-busting ingredients like triclosan come in. The downside to triclosan is that it's also a pesticide that reacts with free chlorine to produce chloroform, a bioaccumulating toxin and probable human carcinogen. Not only can it weaken your immune system and destroy the delicate balance of friendly flora in your intestines, but studies suggest that it may promote the evolution of drug-resistant strains of bacteria.

Hand sanitizers from popular brands like Dial, Purell, Softsoap, Bath & Body Works, CVS, Walgreens, and even Avon Naturals all register at moderate to high hazards in the Cosmetics Safety Database. Among the health dangers of common chemicals in hand sanitizers are cancer, irritation, reproductive concerns, and toxicity to the body. But you don't need to don a hazmat suit or seek out the nearest sink every time you need to rid your hands of germs. There are plenty of non-toxic, mostly natural sanitizers that contain a sufficient amount of alcohol to get the job done.

Our favorite picks, combining powerful protection with safe ingredients, are All Terrain Hand Sanz, Belli Moisturizing Hand Sanitizer, Burt's Bees Aloe Vera & Witch Hazel Hand Sanitizer, EO Hand Sanitizing Spray, and Jao Hand Refresher. Each of these formulas have the ideal concentration of alcohol to destroy harmful germs without harming your health, in addition to nourishing components that keep your hands from looking dry and showing their age. Honorable mentions include CleanWell Natural Hand Sanitizer (substitutes alcohol for thyme, and as a result, leaves your hands smelling like they were dipped in spaghetti sauce), Herban Essentials Lemon Towelettes (simply water, lemon essential oil, and an emulsifier), and Method Hand Sanitizer (points docked for chemical fragrance and dyes).

All Terrain Hand Sanz Active Ingredients: Ethyl Alcohol (62%). Inactive Ingredients: Water Purified, Hydroxyethylcellulose (Wood Cellulose), Vegetable Glycerin, Aloe Vera, Vitamin E, Grapefruit, Orange, Lime Seed Oil Complex, Food Grade Colorant

Belli Moisturizing Hand Sanitizer Active Ingredient: Benzalkonium Chloride 0.1%. Other ingredients: SD Alcohol 40-B, Deionized Water, Hydrolyzed Jojoba Esters (and) Jojoba Esters, PEG-7 Glyceryl Cocoate, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Triethanoloamine, Lactose (and) Cellulose (and) Hydroxypropyl Methylcellulose (and) Ultramatin (and) Retinyl Palmitate, Tocopheryl Acetate (Vitamin E), Citrus Medica Limonum (Lemon) Peel Oil, Disodium EDTA

Burt’s Bees Aloe & Witch Hazel Hand Sanitizer Active Ingredient: Ethyl alcohol 62%. Other Ingredients:  Water, hamamelis virginiana (witch hazel) water, glycerin, fragrance, aloe barbadensis leaf extract.

EO Hand Sanitizing Spray Ingredients: 62% Organic ethanol (non-GMO), purified water, organic lavender essential oil, organic echinacea extract, vegetable glycerin, vitamin E

Jao Hand Refresher Active ingredients: Ethyl alcohol 65%. Inactive ingredients: water, aloe, glycerine, glyceryl polyacrylate, panthenol carbomer, aminomethyl propanol, ppg-20, methyl glucose ether, chamomile and calendula extracts, oils of lavender, tea tree, eucalyptus, geranium, clary sage.