03:04 - Source: CNN
The end of chemical weapons in the U.S.

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On Tuesday, the Pueblo Chemical Depot will begin to destroy the largest stockpile of chemical weapons in the U.S.

Here are nine facts to know about chemical weapons

CNN  — 

The Pueblo Chemical Depot will begin destroying the United States’ largest remaining stockpile of chemical weapons Tuesday in southern Colorado. There are 2,611 tons of World War II-era mustard agent at the Pueblo depot.

Here are nine things to know about these chemical weapons and how we got here:

1. First use: April 22 marks the 100th anniversary of the first use of chemical weapons in modern warfare at Ypres in Belgium.

2. Huge production: From World War I to 1968, the United States produced nearly 40,000 tons of chemical weapons. These weapons were either nerve agents or blister agents.

3. Scary stuff: Mustard agent is a blister agent, which can cause skin redness and itching, eye irritation, scarring, and an increased risk for lung and respiratory cancer.

4. Into the sea: From 1967 to 1970, the U.S. Army disposed of thousands of chemical warfare agents and ammunition into the sea as part of Operation Cut Holes and Sink ‘Em (CHASE).

5. No more: Congress passed a law in 1972 known as the Marine Protection, Research and Sanctuaries Act prohibiting this kind of dumping.

6. Date of destruction: In 1997, the United States ratified the Chemical Weapons Convention Treaty and agreed to destroy all of its chemical weapons by April 29, 2012.

7. Work not done: 90% of the U.S. stockpile – 30,500 tons – was destroyed by the treaty date in 2012 at depots in Alabama, Arkansas, Indiana, Maryland, Oregon, Utah and Johnson Atoll in the Pacific. The remaining 10% – close to 3,100 tons – is at two sites in Colorado and Kentucky.

9. Don’t burn it: Residents in Colorado and Kentucky protested the use of incineration to get rid of the chemical weapons stockpile. The process of neutralization was adopted.

8. Pueblo’s stockpile: The Pueblo Chemical Depot has about 780,000 shells containing mustard agent.

9. The last one: The Blue Grass Army Depot in Richmond, Kentucky, will have the remaining chemical agent stockpile, which is a fifth of the size of the one at Pueblo Chemical Depot. But the Kentucky site has a larger variety of chemical weapons, including nerve agent.