Federal investigators are still looking into the April explosion at a fertilizer plant in West, Texas that killed 14 people. The explosion was called by a chemical called ammonium nitrate, and a new media analysis shows the chemical is stored in locations in Kentucky, Indiana and Tennessee.

Ammonium nitrate is used in fertilizer and explosives. States are secretive about the chemical—they don’t like to broadcast the locations of stockpiles, because their explosive nature means they could be targets for terrorist attacks. And there’s no sort of central registry where any information about ammonium nitrate storage is available to the public. These factors make it difficult to determine whether there’s a risk of explosions similar to the one in Texas in other states.

But a new analysis by DTN/The Progressive Farmer, an agriculture and country life magazine, shows that ammonium nitrate is stored in comparable amounts in several states, including Kentucky, Indiana and Tennessee. The magazine analyzed information from 17 states; 11 of them had facilities that stored the chemical.

In Kentucky, a total of 849 tons of the chemical was stored in 22 places around the state last year. In one of those places, the magazine reports that 23 tons of ammonium nitrate was surrounded by a residential subdivision. Larger amounts are stored in various places around Indiana and Tennessee.

From the article:

DTN’s research and analysis shows Tennessee has 86 solid ammonium nitrate stockpile locations, the largest number compared to the other states that shared data.

Out of those 86 Tennessee sites, 24 reported having an average daily amount of AN stored between 499 tons and 4,999 tons — about 18 to 147 times the amount of AN that ignited in West, Texas.

Indiana’s records to DTN showed stockpiles of solid AN at 12 locations, although just three reported having pure, solid AN while the remainder report mixes of AN and other dry fertilizers.

Compared to individual stockpiles in states like Tennessee and Texas that total in the thousands of tons, Indiana data from 2012 shows that most stockpiles are relatively small in the Hoosier state. However, three Indiana sites that each store an average daily quantity of 454 tons of pure, solid AN sit in towns with populations under 45,000 residents.

Federal investigators think the explosion in Texas was caused by anywhere from 28 to 32 tons of the chemical.

In Kentucky, to store ammonium nitrate a facility needs a permit from the state fire marshal. The office is required to make sure the chemical is stored properly and safely, but there’s no set schedule on how often it needs to be inspected….just “periodically,” according to state fire marshall Bill Swope. If there’s more than 5 tons (10,000 pounds) of the chemical, it has to be reported to Kentucky Emergency Management and local emergency planning commissions.

Jim Bottom, the haz-mat coordinator for the Louisville/Jefferson County Emergency Management Agency, says there are currently no facilities in Jefferson County that have more than 5 tons of ammonium nitrate.