Weather Modification

Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud. The usual intent is to increase precipitation (rain or snow), but hail and fog suppression are also widely practiced in airports.

In the United States, cloud seeding is used to increase precipitation in areas experiencing drought, to reduce the size of hailstones that form in thunderstorms, and to reduce the amount of fog in and around airports. Cloud seeding is also occasionally used by major ski resorts to induce snowfall. Eleven western states and one Canadian province (Alberta) have ongoing weather modification operational programs. In January 2006, an $8.8 million cloud seeding project began in Wyoming to examine the effects of cloud seeding on snowfall over Wyoming's Medicine Bow, Sierra Madre, and Wind River mountain ranges.

In our review of the materials used for cloud seeding we have found the following materials in use:

Acetamide - Known carcinogen and a suspected skin or sense organ toxicant. It is more hazardous than most chemicals in two out of five ranking systems.

Acetone - Suspected cardiovascular or blood toxicant, gastrointestinal or liver toxicant, kidney toxicant, neurotoxicant, respiratory toxicant, and skin or sense organ toxicant.

Aluminum - Suspected cardiovascular or blood toxicant, neurotoxicant, and respiratory toxicant. Ranked as more hazardous than most chemicals in 4 out of 11 ranking systems.

Ammonia - Suspected gastrointestinal or liver toxicant, neurotoxicant, respiratory toxicant, and skin or sense organ toxicant. Ranked as one of the most hazardous compounds (worst 10%) to ecosystems.

Ammonium Chloride - Suspected cardiovascular or blood toxicant.

Ammonium Nitrate - decomposes on heating or on burning producing toxic fumes (nitrogen oxides). Eye, skin, and respiratory tract irritant. Suspected blood toxicant.

Barium - Suspected developmental toxicant, neurotoxicant, and respiratory toxicant.

Barium Chromate - Known carcinogen.

Bismuth - Suspected cardiovascular or blood toxicant, kidney toxicant, and skin or sense organ toxicant.

Boron - Suspected cardiovascular or blood toxicant, neurotoxicant, and respiratory toxicant.

Cadmium - Recognized carcinogen, developmental toxicant, and reproductive toxicant. It is a suspected cardiovascular or blood toxicant, endocrine toxicant, immunotoxicant, kidney toxicant, neurotoxicant, and respiratory toxicant. Ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health.

Carbon Dioxide - Suspected developmental toxicant, neurotoxicant, and reproductive toxicant.

Catechol - Suspected carcinogen, gastrointestinal or liver toxicant, neurotoxicant, and skin or sense organ toxicant.

Cesium - Suspected neurotoxicant.

Cobalt - Recognized carcinogen. It is a suspected cardiovascular or blood toxicant, gastrointestinal or liver toxicant, immunotoxicant, kidney toxicant, neurotoxicant, respiratory toxicant and skin or sense organ toxicant. Ranked as one of the most hazardous compounds (worst 10%) to human health.

Copper - Suspected cardiovascular or blood toxicant, developmental toxicant, gastrointestinal or liver toxicant, reproductive toxicant, and respiratory toxicant. Ranked as one of the most hazardous compounds (worst 10%) to human health.

Cupric Sulfate - Suspected cardiovascular or blood toxicant, gastrointestinal or liver toxicant, kidney toxicant, and neurotoxicant.

Cyclotrimethylenetrinitramine - Suspected carcinogen, cardiovascular or liver toxicant, and neurotoxicant.

Dimethyl Acetamide - Suspected gastrointestinal or liver toxicant, and skin or sense organ toxicant.

Dimethyl Sulfoxide - Suspected cardiovascular or blood toxicant, and skin or sense organ toxicant.

Epoxy Resin - Suspected skin or sense organ toxicant.

Ethanol - Suspected carcinogen, cardiovascular or blood toxicant, developmental toxicant, endocrine toxicant, gastrointestinal or liver toxicant, neurotoxicant, respiratory toxicant, and skin or sense organ toxicant.

Ethylene Glycol - Suspected cardiovascular or blood toxicant, developmental toxicant, endocrine toxicant, gastrointestinal or liver toxicant, kidney toxicant, neurotoxicant, reproductive toxicant, respiratory toxicant, and skin or sense organ toxicant.

Ethylenediaminetetraacetate - Decomposes on heating, producing toxic fumes of nitrous oxides. Eye, skin, and respiratory irritant. May cause effects on the kidneys.

Ferric Chloride - This compound is a strong irritant to skin and tissue. When heated to decomposition it emits highly toxic fumes. It will react with water to produce toxic and corrosive fumes. Symptoms if inhaled include wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest.

Hexabromobenzene - More hazardous than most chemicals in 2 out of 2 ranking systems. Ranked as one of the most hazardous compounds (worst 10%) to human health.

Hexachlorobenzene - Known carcinogen and developmental toxicant. It is a suspected cardiovascular or blood toxicant, endocrine toxicant, gastrointestinal or liver toxicant, immunotoxicant, kidney toxicant, neurotoxicant, reproductive toxicant, and skin or sense organ toxicant. More hazardous than most chemicals in 13 or 14 ranking systems. Ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health.

Hexachlorocyclohexane - Recognized carcinogen. It is a suspected cardiovascular or blood toxicant, endocrine toxicant, gastrointestinal or liver toxicant, immunotoxicant, kidney toxicant, neurotoxicant, respiratory toxicant, and skin or sense organ toxicant.

Hexachloroethane - Recognized carcinogen. It is a suspected developmental toxicant, gastrointestinal or liver toxicant, kidney toxicant, neurotoxicant, reproductive toxicant, respiratory toxicant, and skin or sense organ toxicant. More hazardous than most chemicals in 11 out of 14 ranking systems.

Lead - Known carcinogen, developmental toxicant, and reproductive toxicant. Lead is a suspected Cardiovascular or blood toxicant, endocrine toxicant, gastrointestinal toxicant, immunotoxicant, kidney toxicant, neurotoxicant, repiratory toxicant, skin or sense organ toxicant. Ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health.

Lithium - Suspected kidney toxicant and neurotoxicant.

Liquid Propane - Suspected neurotoxicant.

Lithium Carbonate - Recognized developmental toxicant. It is a suspected cardiovascular or blood toxicant, endocrine toxicant, gastrointestinal or liver toxicant, neurotoxicant, and skin or sense organ toxicant.

Magnesium - Suspected respiratory toxicant.

Methanol - Suspected developmental toxicant, gastrointestinal or liver toxicant, neurotoxicant, respiratory toxicant, and skin or sense organ toxicant.

Nitroglycerine - Suspected carcinogen, cardiovascular or blood toxicant, gastrointestinal or liver toxicant, neurotoxicant, and respiratory toxicant. More hazardous than most chemicals in 6 out of 9 ranking systems.

Nitrosol - Suspected cardiovascular or blood toxicant, gastrointestinal or liver toxicant, kidney toxicant, neurotoxicant, and skin or sense organ toxicant. Ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health.

Organic Nitrates - Suspected cardiovascular or blood toxicants.

Pentabromobenzene - Suspected carcinogen and developmental toxicant.

Pentachlorobenzene - Suspected gastrointestinal or liver toxicant, kidney toxicant, and neurotoxicant. Ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health.

Phenol Formaldehyde Resin - Suspected immunotoxicant.

Potassium Iodide - Suspected cardiovascular or blood toxicant, and developmental toxicant.

Potassium Perchlorate - Suspected cardiovascular or blood toxicant.

Pyrrolidone - Suspected gastrointestinal toxicant.

Quinoxaline - Known carcinogen. Suspected gastrointestinal or liver toxicant.

Silver Iodide - Thermal decomposition may release corrosive hydrogen iodide. Acute exposure: No data available. Chronic exposure: No data available.

Sodium Chloride - Suspected cardiovascular or blood toxicant.

Sulphur - Skin, eye, and respiratory irritant. Pulmonary function may be reduced. Trachiobronchitis is a frequent occurrence. Chronic bronchitis and chronic sinus effects. Bronchopulmonary disease may occur, complicated by emphysema. Asthma is a frequent complication.

Xylene (Shellac) - May cause Irritation of the skin, eyes, nose, and throat; difficulty in breathing; impaired function of the lungs; delayed response to a visual stimulus; or impaired memory.