New York Mayor Michael Bloomberg’s office was recently sent mail with traces of the poison ricin.

There were references in the letters to tighter gun control which he supports.

As the gun control debate continues, Colorado has passed some of the country’s toughest gun control measures.

But gun industry-related businesses in Colorado say the new regulations are threatening their existence.

Retail sales in Colorado related to hunting totaled more than US$465 million in 2011, according to the Congressional Sportsman’s Foundation.

But while some small businesses in Colorado say they are deeply concerned about the future, others are less worried, and predict the new gun control laws will have very little negative impact on their bottom line.

Some experts believe the impact of the new legislation will only have a minimal long-term effect on the Colorado economy.

Prof Mac Clouse, Daniels College of Business, University of Denver, said: “I think eventually it’ll wear off and people will stop making a statement, and they’ll go back to the reason they were going to go to Colorado in the first place.”