16 March 2015
After many years of speculation, it has finally been established that hydrazine is not a prevalent contaminant in contemporary smokeless tobacco products (STPs).
The presence of hydrazine has only been reported once in a limited sample of cigarette tobacco and tobacco smoke some 40 years ago. But this study has been cited many times as evidence that hydrazine is present in smokeless tobacco products. To date, no one has examined STPs for its presence.
Hydrazine is found in maleic hydrazine, which is used as a sucker growth inhibitor on tobacco crops – suckers are side shoots, which if not removed affect the quality and yield of the tobacco plant. Hydrazine is classified as a possible human carcinogen by the International Agency for Research on Cancer, which can have negative effects on the central nervous system, liver and kidneys.
Hydrazine is on the list of the FDA's "Harmful and Potentially Harmful Constituents" HPHC list, which is why there is a public health interest in the compound and to what degree it occurs in tobacco.
Scientists at British American Tobacco, in collaboration with Professor Brad Rodu of the University of Louisville, undertook a comprehensive survey of toxicants in STPs. They developed and carefully validated a highly sensitive method for determining levels of hydrazine in STPs.
This method involves first treating aqueous extracts of STPs with pentafluorobenzaldehyde, which reacts with hydrazine to form decafluorobenzaldehydeazine (DFBA). The DFBA is then quantified by gas chromatography–mass spectrometry to determine hydrazine levels. This method was validated using five different types of STPs.
The researchers used the validated method to analyse hydrazine content in a wide range of commercial STPs from the USA and Sweden. The product types included in the survey were snus, chewing tobacco, moist snuff, dry snuff, plug and pellet products, representing 90% market share of the major STP categories.
None of the STPs were found to contain hydrazine above the current limits for detection (<10ng/g product) or quantification (26.5ng/g). Close investigation of the analysis results identified the possible presence of trace levels of hydrazine in 34 of 70 samples; while in the other 40 there was no evidence of hydrazine being present. The trace elements were at such low levels they cannot be quantified using currently available analytical techniques.
‘Our results indicate that hydrazine is not a prevalent contaminant of contemporary STPs, and in the minority of cases where hydrazine might possibly be present, the levels are substantially lower — by at least an order of magnitude — than those reported previously,’ says Kevin McAdam, principal scientist at British American Tobacco.
This is the second in a series of 10 manuscripts analysing constituents in smokeless tobacco products.
1. Liu YY, Schmeltz I, Hoffman D. ‘Chemical studies on tobacco smoke. XXVII Quantitative analysis of hydrazine in tobacco and cigarette smoke’. Analytical Chemistry 1974, 46: 885-889.
2. McAdam et al: ‘Analysis of hydrazine in smokeless tobacco products by gas chromatography-mass spectometry’. Chemistry Central Journal.
3. McAdam et al, ‘Polycyclic aromatic hydrocarbons in US and Swedish smokeless tobacco products’. Chemistry Central Journal.
Notes to Editors