Q: I deal with hazardous materials. The government has very strict safety regulations, which entail great expenses. Must I observe these regulations?
A: Rav Y.Y. Shmelkis (Beis Yitzchak, C.M. #77) addresses the case of a person who sold kerosene privately in his basement. A neighbor, concerned about the possibility of fire, reported it to the authorities, who required the seller to install metal doors at great expense. He sued the neighbor in beis din for reporting him to the authorities and causing him such expenses.
Beis Yitzchak ruled that Torah law also requires such precautions, because of the great danger of fire. He also cites from the Bach (C.M. 155:56) that dina d’malchusa applies regarding precautionary measures from damage to neighbors. He writes that even the Shach (C.M. 73:39), who rules that dina d’malchusa does not apply when against Torah law, would agree for issues of public safety, since these regulations are common practice (Pischei Choshen, Nezikin 13:). Thus, you must observe the federal safety regulations