Road-Ice Melting Gets Ecologically Friendly: Green Vehicles Articles: Eco20/20

Road-Ice Melting Gets Ecologically Friendly

Ice melting is a necessity in some climates, but salt chemicals may be toxic to small animals, and can harm larger ones if taken in quantity. Luckily, environmentally friendly options do exist.

Conventional De-icing has Already Gotten Eco-friendlier

* In the past, salt suppliers often used poisonous additives to enhance salt's performance. Chromium was added as a corrosion inhibitor, but in some forms chromium can be a toxic heavy metal. Sodium Ferro-cyanide and ferric Ferro-cyanide were once added to prevent caking; but specific conditions may cause Ferro-cyanide compounds to generate cyanide, a severe poison. These poisons might still be used in special cases, but are not commonly sold to the public, so today's deicers are already moving in the right direction.

* In general, roadway and household deicers are made from single or blended chlorides (calcium chloride, sodium chloride, potassium chloride, magnesium chloride). Sodium chloride is often used alone. Calcium chloride may be used alone, but is also the primary ingredient in many blends.

o Rock salt is sodium chloride. It's endothermic; which means that when you use rock salt, you get slush. Rock salt absorbs the sun's heat and uses it to melt ice into liquid brine. It is effective down to a few degrees over zero. It does not aid evaporation, so water left behind might seep, refreeze, and cause damage to porous surfaces.

o Solutions of calcium chloride are exothermic; releasing heat to melt the ice. Calcium Chloride is also hygroscopic, meaning it can absorb and retain water. Calcium Chloride mixes with water to help it evaporate, and will melt ice and snow down to 25 degrees below zero. It is kinder on walkways, shingles and aluminum gutters but must be kept in an airtight container or it will convert to water.

The Health Effects of Ice-melting Salts

Even without poisonous additives, deicer salts can still be toxic; especially for pets and wildlife.

* For adult humans, the most common effect of exposure to rock salt is skin irritation. Calcium Chloride is slightly harsher, causing more skin-damage and respiratory irritation. Cover your hands when using these products.

* Children are more severely affected by road salts than adults, especially if they don't wash after playing outdoors where the salts have been used.

* Pets and wildlife are the likeliest to become sick from ingesting ice-melt products. A small animal may lick the chemicals from wet paws, drink contaminated water, or eat contaminated snow. A larger animal, like a deer, may drink contaminated water, or make a habit of eating deicer because the product smells like a 'salt lick'. Symptoms of deicer salt poisoning can range from excessive thirst, vomiting and diarrhea, to tremors, disorientation, seizures and even death depending on the amount of salts ingested.

The Options for Salt-free Deicers

* Calcium magnesium acetate is a salt-free biodegradable alternative being explored by road crews. It works by interfering with the bond between snow particles and the road surface. In recent years, there has been considerable improvement in the product. It still takes more CMA, initially, to deice a road, as compared to salts, but it lasts longer and subsequent applications may be lighter. The temperature range is equivalent to rock salt.

* SafepawsTM is the brand name of an exothermic compound made of a modified crystalline amide core infused with a special glycol admixture. Proponents say it won't irritate pets' paws, won't damage human skin, won't poison pets or local wildlife, and it's better for surrounding plants.

* Sand or gravel, while not able to melt ice, can provide traction for better footing on snow, if that's the only feature required.

Although the salts have themselves become more eco-friendly, the guiding principle should always be to use the most environmentally sound process that will still accomplish the job; so for household use the best combination is SafepawsTM for walkways, where ice is a serious hazard; and plain old sand where traction is the only concern.