Some speculation says that the seeming delay in certification of Andrea Rossi’s E-Cat is because of the use of hydrogen. Hydrogen is considered dangerous at some levels and can present a problem for safety ratings.
However, hydrogen is not the only dangerous gas used domestically. Most water heaters use natural gas, as do gas stoves. Rural areas use propane for heating and cooling, and many vehicles use propane fuel. As far as that goes, gasoline is a hazardous chemical, too, that is used domestically.
In addition, hydrogen is a lighter-than-air gas, so if it is released accidentally, it rises indefinitely. It’s already used as vehicle fuel in Tokyo. Natural gas is heavier-than-air, and sinks. This is what caused the explosion in New London, Texas, in 1937, when 300 students were killed.
The E-Cat uses about a tablespoon of hydrogen, and it is enclosed in a canister. Any safety “concerns” with the use of hydrogen in the E-Cat will be strictly hypocritical.