In addition to the synthetic marijuana and stimulants commonly known as bath salts seized as part of the investigation, detectives froze about $900,000 in business bank accounts - a haul that Montgomery County District Attorney Risa Vetri Ferman described as about two days worth of revenue for the company.
"The fact that we were able to seize so much money over two days tells me that this is a big business - lots of volume, lots of profit," she said.
Synthetic marijuana is made by mixing natural herbs with chemicals to deliver a high like that of cannabis. So-called bath salts, also made using chemicals, provide users with an experience similar to that of cocaine or methamphetamine.
A federal ban on the substances was signed in July. Last year, Pennsylvania joined 33 other states in banning both products after a rise in violent incidents, many involving teenagers who legally bought and used synthetic drugs.
A 17-year-old Upper Moreland youth suffered serious injuries in June 2011 shortly after smoking synthetic marijuana, climbing through a car window, removing his pants, and leaping from the third floor of a parking garage at the Willow Grove Park mall.
Lehigh County District Attorney James B. Martin said he had linked at least one homicide to hallucinations based on use of the drug.
Since those bans went into effect, authorities statewide have charged a handful of retail-level synthetic drug vendors, including a Pottstown store owner and cashier accused in July of selling synthetic marijuana to a group of customers later involved in a wreck that killed two. But Thursday's case is one of the first to target an alleged multistate distribution ring.
Prosecutors said Grossman was believed to have peddled his wares at conventions in Atlantic City, out of a storefront in New Castle, Del., and to a network of customers within Pennsylvania.
Also arrested Thursday were Grossman's partners in a subsidiary business, Insense Solutions, that also allegedly sold the products - his 24-year-old son, Jason; Mangat Malwinder of Leesport, Pa.; and Rajwant Thind of Orefield, Pa.
Owners and employees of five gas stations and convenience stores in Allentown, Schwenksville, and Upper Frederick, Upper Perkiomen, and South Whitehall Townships have also been charged in the case.
District Judge Catherine Hummel-Fried charged all 15 Thursday afternoon with counts ranging from criminal conspiracy to the manufacture and delivery of a controlled substance.
It remains unclear whether Grossman and his codefendants had retained attorneys.
A preliminary hearing was set for Thursday.
Contact Jeremy Roebuck at 267-564-5218, firstname.lastname@example.org, or follow @jeremyrroebuck on Twitter.