The Effect of Consumption of Hempen Ale¨ on Urine Cannabinoid Screens

Published: Journal of Analytical Toxicology, Volume 23, Number 6, October 1999, pp.563-564

The recent rise in popularity of hemp-derived products presents an interesting dilemma to toxicologists and employers who conduct drug testing in the workplace. These products may range from hemp oils, marketed for their beneficial health-related effects, hemp-based lip balms, coffee, beer brewed with hemp seeds, and a number of other hemp-containing products.

The Division of Forensic Toxicology, Armed Forces Institute of Pathology conducted a study to determine the validity of the contention that a positive cannabinoid urinalysis may result from drinking Hempen Ale (Frederick Brewing Co., Frederick, MD), a beer brewed with hemp seeds that do not contain THC but do contain other cannabinoids. Nine subjects drank Hempen Ale ad libitum within a single day (range, 5 to 14 servings). Urine specimens were collected throughout the drinking period. A 10th subject drank two Hempen Ales each day over an 8-day period; urine specimens were collected before and after drinking. A total of 146 urine specimens were collected and submitted to the Division of Forensic Toxicology, Armed Forces Institute of Pathology for analysis using four commonly employed immunoassays to test the urine specimens that were collected: Abbott AxSYM (FPIA), STC Micro-Plate (EIA), Roche Online (KIMS), and Immunalysis (RIA). Each of the immunoassays was performed in accordance with the manufacturer specifications (1–4). Positive results were subsequently analyzed for 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (11-THCCOOH) using a gas chromatography–mass spectrometry method (GC–MS) (5).

The random urinalysis program to which all active-duty members of the United States military are subject has been shown to be an effective deterrent for the use of illicit substances among those military members. An ongoing issue in the investigation and prosecution of positive urinalysis results is the possibility of use of a licit substance (e.g., prescription drugs or natural substances) causing the positive result. A classic example of this issue is the consumption of pastries containing poppy seeds resulting in a positive opiate urinalysis.

This study was undertaken to evaluate the possibility that Hempen Ale will become the cannabinoid equivalent to the poppy seed and, thereby, evaluate the legitimacy of a Hempen Ale defense. Although Hempen Ale currently has a limited availability, there is a wide enough distribution of this beverage to become an issue in the random urinalysis program. It is possible that military members whose random urinalysis yields a positive cannabinoid result will make the claim that they simply drank Hempen Ale and for this reason were positive on the marijuana screen. A similar claim has already been successfully made in at least two cases in which the defendants denied that they had smoked marijuana, but had instead consumed commercially available hemp-containing products. The validity of this contention was tested in this study in order that proper defense and prosecution of positive cannabinoid urinalysis cases may proceed without undue burden on either the defendant or on the government (6).

The Frederick Brewing Company states that some of the hemp seed protein content is retained in the beer (7). A very limited evaluation has been reported in the literature suggesting that Hempen Ale ingestion does not produce cannabinoid-positive urinalysis results (8).

11-THCCOOH and 11-THCCOOH-d3, for use as the internal standard, were obtained from Research Triangle Institute, and stock solutions of 2 mg/L and 4 mg/L, respectively, were prepared in absolute ethanol. All solvents were Fisher pesticide grade, and all chemicals were Baker reagent grade. Hempen Ale was provided through the courtesy of the Frederick Brewing Co.

AxSYM® calibrators, controls, and reagents for the AxSYM Cannabinoids assay were purchased from Abbott Laboratories (Abbott Park, IL). Immunalysis THC-Cannabinoids Direct RIA kits were purchased from Immunalysis Corp. (San Dimas, CA). STC Cannabinoids Micro-Plate EIA kits were a gift from STC Technologies, Inc. (Bethlehem, PA). The ONLINE® Cannabinoids-ES 50/100 (Roche Diagnostic Systems, Inc., Nutley, NJ) assay was performed at the Ft. Meade Forensic Toxicology Drug Testing Laboratory using their kits and performed by their personnel.

In accordance with the normal procedure followed in Forensic Urine Drug Testing Laboratories, no further analysis was performed on samples that screened negative for cannabinoids. Samples that screened positive on any of the cannabinoid immunoassays were subsequently analyzed for the presence of 11-THCCOOH using a quantitative GC–MS method that uses an acid extraction of the analyte from urine followed by the formation of the methyl ester derivative (5). The derivatized extracts were analyzed using an HP 5970 GC–MSD equipped with a DB-5 column and operated in the selected ion monitoring (SIM) electron impact mode. The ions monitored were 313, 357, 372 (11-THCCOOH), and 316 (11-THCCOOH-d3), and 313/316 was used as the quantitation ratio.

Of the 146 specimens analyzed, 136 yielded a negative result on all 4 of the immunoassays and 10 specimens were positive only on the Immunalysis RIA. Each of those 10 positive samples, which screened positive for levels greater than the 25-ng/mL cutoff with this assay, was confirmed negative by the GC–MS technique at a 10-ng/mL cutoff. It is possible that the Immunalysis immunoassay was the only cannabinoids screen yielding any positive results because it was run with the lowest cutoff— 25 ng/mL—compared with the 50-ng/mL cutoff for the other assays. The Division of Forensic Toxicology, however, has used the Immunalysis RIA for approximately two years for the detection of cannabinoids in blood and has noted a very high false-positive rate in the performance of routine casework, which includes specimens from both postmortem and nonfatal cases.

It is important to note that the 10 positive cannabinoid results that were obtained using the Immunalysis assay did not conform to a pattern that would be expected if the reason for the positive result were the accumulation of cannabinoids in the urine of subjects drinking a hemp-containing beverage. The samples yielding positive results were not from consecutively collected urine specimens, not every subject had a positive result, the positive results did not appear exclusively in the subjects drinking the largest amount of Hempen Ale, nor were the positive samples exclusively those collected late in the drinking period.

It is clear from this study that the consumption of Hempen Ale, in a pattern of normal social drinking, including chronic, low-dose consumption, does not produce a positive urinalysis result using four of the commonly employed cannabinoid immunoassays with GC–MS confirmation. The use of a Hempen Ale defense for a positive cannabinoid urinalysis result similar to the poppy seed defense frequently employed in positive opiate urinalysis cases is clearly not viable or valid.

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