Marijuana is the third most popular recreational drug in America, behind alcohol and tobacco. It is estimated that nearly 100 million Americans use it.Alaska, Oregon and Washington, D.C., recently have legalized marijuana’s recreational use and distribution. Many employers in Iowa are wondering how this trend will affect their workplace.But frankly, unless federal and state laws are changed, the answer is not at all.Remember, marijuana still is illegal under federal law (the Controlled Substances Act) and Iowa law.