Testing Methods for Lead In Cannabis E-Cigarettes
Jeff Rawson, Victoria Turkington, Anna Blanchfield, Clarence Ndubisi, Canyon Aspy, Christoffer Abrahamsson, and Alexandra Wagner with Harvard University, Department of Chemistry and Chemical Biology
Aaron Specht with Purdue University, Natural Resources, and Environmental Sciences
Michael Kahn, Giancarlo Feula, Yihai Ding, and Julie Martellini with MCR Labs
Marc Weisskopf and David C. Christiani with Harvard University, T.H. Chan School of Public Health
George M. Whitesides with Harvard University, Kavli Institute for Bionano Science and Technology
Lead is one of four heavy metals that all cannabis goods must be tested for in the state of Massachusetts. There is no level of exposure to lead that is considered safe; cannabis goods that exceed the 500 ppb action limit must be retested or discarded. E-cigarettes must be submitted in “final form” to testing laboratories, where the oil is extracted from cartridges and heavy metal content evaluated. Yet, in December of 2019, 12% of 109 previously compliant cartridges suddenly exceeded the action limit for lead – the largest of which was 29,814 ppb. We compare Inductively Coupled Plasma Mass Spectrometry (ICP-MS) of the oil to elemental analysis of cartridge hardware and ICP-MS analysis of e-cigarette aerosol.
X-ray Fluorescence was performed on 37 whole cartridges available on the regulated market and ICP-MS analysis performed on the components of 3 disassembled CCELL cartridges. Aerosol generation was automated and the aerosol captured on cellulose filters. Filters were submitted for ICP-MS analysis.
XRF analysis of whole cartridges revealed lead concentrations in excess of 500 ppb in 22% of e-cigarette cartridges that passed oil testing. Still, XRF of whole cartridges inadequately captures the composition of heating elements. Whole CCELL cartridges lie below the limit of detection for lead, but component analysis revealed lead concentrations of 578 ± 240 ppb in the wire filament and 199 ± 99 ppb in the ceramic of CCELL cartridges. ICP-MS analysis of the e-cigarette aerosol is highly variable and low throughput.
We must assume that all lead contained in cartridges may be leached into cannabis oil until proven otherwise. Producers should submit representative, empty, cartridges for appropriate component testing and a representative cannabis oil sample, in an inert container, for elemental analysis. Aerosol testing is not practical or useful for heavy metals screening on the regulated market.