54 THE SCIENTIST | the-scientist.com
COURTESY OF CANNASAFEcentrations of contaminants are safe. Most
research on pesticide toxicity, for example,
assumes ingestion of products, but cannabis
is often smoked—a mode of consumption
that poses different risks, Hudalla explains.
“There’s been very little study that’s focused
on the thermal combustion or degradation
of pesticides prior to inhalations.”
While government and academic
research is lacking, some labs have con-
ducted their own studies on the risks of
certain pesticides in cannabis cultivation.
In 2015, Conrad’s firm was asked by a
local Colorado consumer advocacy group
if myclobutanil, a fungicide that prevents
mildew on plants, posed risks to peo-
ple smoking cannabis. During a routine
inspection of cannabis farms a few weeks
earlier, state officials had noticed work-
ers applying the pesticide, which is con-
sidered safe at very low concentrations in
agricultural crops, but is prohibited for use
in tobacco cultivation.Conrad’s chemical analysis found
that, once heated past the boiling point,
myclo butanil generates hydrogen cyanide.
Though unlikely to be lethal at the levels
used in cannabis cultivation, the compound
should not be inhaled by people with weak-
ened health, Conrad says. After he shared
his findings with the state’s department of
health, Colorado and several other states
banned the use of the fungicide in cannabis
cultivation. Similar cases have played out
for other pesticides. “A s a general rule, the
labs [are] advocating mainly on the behalf
of consumers that we should be doing more
testing,” says Conrad.
Some data suggest that increases in
this sort of testing have made cannabis
products safer over time. When Califor-
nia first mandated pesticide testing for
cannabis in 2018, more than 24 percent
of products tested by CannaSafe, Fra-
zier’s company, failed the state’s pesticide
standards. By the start of 2019, that rate
had dropped to 1.5 percent—to Frazier a
sign that the testing system encourages
growers to be more careful about the
products they use.However, safety lapses do happen. Last
year, Colorado officials randomly sampled
cannabis products sold around Denver
and discovered yeast and mold on prod-
ucts from batches that testing labs had
declared contamination-free. The findings
triggered a major recall that affected 144
dispensaries around the city. It’s not clear
who in the supply chain was at fault. While
some experts suggest that such situations
could be caused by microbes growing after
products are packaged, some similar situ-
ations in the past have involved error or
manipulation from labs or growers. (See
sidebar, “Bad Behavior.”)A push for standards
While a certain degree of variation in prod-
uct testing is inevitable, particularly for
agricultural products that themselves show
natural variation, efforts are afoot to tackle
variability in potency and safety testing in
a systematic w ay. In addition to conducting
random testing of products that end up on
shelves, a number of state regulators have
raised the bar for becoming a licensed lab.
Of the 26 states with mandatory testing, 18
require some form of accreditation, usually
ISO 17025, a rigorous and expensive certifi-
cation issued by the International Organi-
zation for Standardization for which labs
have to provide extensive data to convince
auditors that their methods are accurate.
However, even accredited labs appear to
have difficulties replicating one anoth-
er’s results—something that puzzles Holly
Johnson, chief science officer at the Ameri-
can Herbal Products Association (AHPA),
which represents more than 350 compa-
nies doing business in herbal products.
One solution could be nationwide,
compulsory proficiency testing, whereby
an independent third party sends lab
researchers an unknown sample to see
whether they can accurately analyze its
ingredients. This sort of oversight is stan-
dard for US companies testing water,
biofuels, agricultural goods, and many
other products, Conrad notes. However,
a national proficiency program for canna-
bis labs is infeasible because federal law
prohibits the transportation of high-THC
cannabis across state lines, he explains.BIO BUSINESSTESTING TECHNIQUES:A CannaSafe chemist
uses high-performance liquid chromatography
to analyze samples for potency.