Shanghai Broker Touts Synthetic Drugs Shipped to U.S. in Violation of Trade, Tariff Rules

Emails show how a major Chinese chemical exporter is conspiring to evade U.S. tariff and trade policy to get synthetic THC analogues into America's recreational drug market.

THC-P products available for sale at a convenience store in Lewiston, Maine.

How are convenience stores and gas stations throughout the U.S. able to supply so-called “gas station weed” to customers with minimal regulatory oversight and for dirt cheap prices?

The answer may lie in messages from a relatively unknown chemical factory in China.

An email chain obtained by The Robinson Report shows that one industrial chemical supplier with manufacturing facilities in Zhejiang and Anhui provinces in China, as well as one in Thailand, has a three-step plan for getting knock-off weed from the Peoples’ Republic of China to your corner convenience store.

The correspondence shows how the Shanghai-based chemical broker is trying to flood the U.S. with cheap synthetic drugs — in this instance, THC-P — via a fine-tuned process that illegally circumvents and undermines American tariffs and import controls.

In the email chain, a representative of Shanghai Minstar Chemical Co. Ltd. repeatedly offers to help a U.S. cannabis business import lab-made THC analogs by evading inspections, disguising the chemicals as innocuous industrial products, and structuring large orders into smaller duty-free parcels.

THC — specifically THC Delta 9 — is the primary psychoactive ingredient in traditional cannabis. But the legalization of cannabis and the loosening of cannabis laws have given rise to a market for THC-adjacent synthetic drugs that are cheaper, unregulated, and very, very sketchy.

Shanghai Minstar Skirts Tariffs

In messages sent throughout 2024, an export manager for Shanghai Minstar Chemical Co., Ltd. — a Chinese company that purports to be registered with the Food and Drug Administration (FDA) — pitched multiple workarounds to “ship cannabis stably, smoothly and safely, no Customs, no tariff.”

The steps included mislabeling THC-related compounds as benign fragrance ingredients; undervaluing invoices; routing through a “special courier” that would “avoid both China and US Customs”; repacking bulk orders into many sub-$800 packages designed to qualify for the de minimis exemption; and, later, moving production or transshipment through Thailand to sidestep U.S. China-tariff exposure.

The recipient of these messages was a U.S.-based cannabis business operator who later turned the messages over to U.S. Customs and Border Protection (CBP). A CBP staffer included in the email chain said the agency would investigate Shanghai Minstar Chemical, Co., but an agency spokesperson declined to comment for this story.

The Chinese broker, who went by the name David Pan, explicitly described how the tariff and customs subversion would work, including falsely labeling THC-related products as more common industrial chemicals and declaring fraudulent values for packages.

“We are very professional to ship cannabis products to US market. When we shipping to US market, we usually label it with similar upstream products, such as Olivetol (CAS 500-66-3)… [and] 2,4-dihydroxy-6-propyl-benzoic acid methyl ester (CAS 55382-52-0)…,” wrote Minstar’s exporting manager.

For large orders, he added, “I could cut declaration value… If I declare lower value in invoice, then you could save lots of tariff.”

What is “Gas Station Weed”?

THC-P and other chemicals commonly described as gas station weed are not the equivalent of the flower or extracts derived from cannabis sativa or cannabis indica, the two primary psychoactive strains of the cannabis plant. But many of these chemicals, including THC-P, have psychoactive properties or can be easily converted into psychoactive substances.

Some of them, such as THC-P, have also been found to have stronger negative effects, such as tachycardia, anxiety, and even psychosis. In one case, documented in a medical journal in February, a single use of THC-P induced psychosis and a suicide attempt.

THC-P products are broadly available throughout Maine, including at a convenience store in Lewiston, where the product pictured below was purchased.

The chemicals offered by Shanghai Minstar include dozens of molecules the naturally occur in only small amounts in the cannabis plant, like THC-P, but can be treated or converted to produce a recreational drug.

Among the most common of these chemicals is THC-P, a molecule that has just two additional carbon atoms added to the Delta 9 THC molecule. THC-P is found in natural cannabis in trace amounts, but the versions of it available in U.S. are almost all made in a lab, with CBD oil being the primary starting ingredient.

The “Hemp Loophole” and THC-P

Because the drug can be produced from CBD derived from the hemp plant, smokable products and edibles that contain THC-P may be legally be sold in the U.S., including in Maine, at gas stations and convenience stores without the hassle of licensing through the Office of Cannabis Policy (OCP).

Or, perhaps, it’s more accurate to say that there is enough of a pretense of legality that c-store owners are willing to take the risk, and no one in the government is asking questions.

The result is that Chinese made synthetic drugs have flooded the market for mind-altering substances through the least regulated channels. The danger of THC-P, though low in comparison to fentanyl and other synthetic street drugs, stems in part from the inconsistent production, lack of transparency, and quasi-criminal nature of the supply chain. THC-P is new, poorly understood, understudied, and companies like Shanghai Minstar and their U.S. customers are moving as fast as possible to exploit American ignorance.

Although most American’s understand that Chinese companies operate according to a different set of ethics, David Pan’s clear articulation of how it will cheat U.S. customs is nonetheless shocking for its brazenness. The method described in the email also raises the possibility that virtually all THC-P on the market has been produced in a Chinese lab, regardless of whether it’s described as originating in America.

[RELATED: Cannabis Firms Sue Over Unregulated “Hemp Loophole” Products Flooding Market…]

Shanghai Minstar offers not only to break orders into multiple packages to sneak below de minimis thresholds but also to route goods through a U.S. location for “domestic” relabeling and delivery. These tactics are presented as ways to reduce scrutiny and conceal Chinese origin.

“There are 2 ways… [1] ship by DHL… with lower value than its actual value in another false common chemical name… [2] send via special courier… [that] has ability to avoid both China and US Customs… goods [go] to some US warehouse… then [a] local courier… deliver to customers,” Pan said.

“Even big quantity also be repacked into small drums… only small packages could be easier to clear in Customs and avoid tariff…. There are more than 1 billion small parcels from China to USA every year done in this way,” the broker wrote, proposing 5-kilogram drums and two-week delivery windows.

Google Maps provides this satellite image for Shanghai Minstar’s public address

According to a lawsuit that rocked the American cannabis and hemp industry earlier this year, Shanghai Minstar Chemical Co. Ltd.’s U.S.-based partner is Hau Processing, a Welby, Colorado-based hemp processor.

In July 2025, Texas-based hemp companies MC Nutraceuticals and its subsidiary MC Botanicals filed a federal lawsuit against North Carolina’s Asterra Labs and its parent company Rise Capital, alleging breach of a December 2024 partnership agreement in which MC would source and market hemp products while Asterra handled funding and order fulfillment.

In response, Asterra filed a counter-claim that included, among other things, the allegation that its accusers were sourcing Chinese-made cannabinoids from Shanghai Minstar Chemical Co. Ltd. via Hau Processing in a manner that mirrors the process described in the email chain reviewed by The Robinson Report.

Breaking the Law

The Minstar correspondence does not read like a misunderstanding of U.S. rules. It reads like a how-to on beating them.

If executed, the plan would tick boxes for false statements, smuggling, civil customs fraud, import violations, and origin-marking offenses—and, because the target cargo is THC analogs for vapes, those involved could face potential Controlled Substances Act exposure under the Analogue Act and DEA’s position on synthetic THC.

Since 2018, imports from China have faced additional “Section 301” duties across large swaths of the tariff schedule. Vendors that undervalue or disguise origin to dodge those duties risk civil and criminal exposure. CBP also has stepped up anti-transshipment warnings in 2025.

Shanghai Minstar’s pitch explicitly tried to make those duties disappear—by falsely describing the goods, splitting shipments to trigger de minimis, and projecting “no tariff at all” if routed via a future Thai plant.

Under CBP’s de minimis rule, though, port directors can deny duty-free entry if they believe “several lots [are] covered by a single order… sent separately for the express purpose of securing free entry,” and Congress and CBP have further tightened low-value-entry policy this year.

In reality, the U.S. has almost no tools to effectively punish the Chinese operators engaged in this behavior, and it’s unclear what legal risks American customers would face.

Last month, the House Committee on Homeland Security heard testimony about Chinese transnational criminal groups that are cultivating and trafficking black-market cannabis within the United States’ borders.

Although the U.S. has made concerted efforts to combat Chinese fentanyl precursors from flowing into Canada, Mexico, and ultimately the United States, little attention has been paid toward a national strategy to combat cannabis and synthetic cannabis-adjacent drugs that are now sold legally through unregulated sale points in convenience stores and smoke shops, including in Maine.