Cadmium, lead, and thallium in smoke particulate from counterfeit cigarettes compared to authentic US brands

Abstract

Smoking remains the leading cause of preventable disease in the United States. Exposure to tobacco smoke leads to cancer, heart and lung disease, and addiction. The origin of the tobacco and cigarette manufacturing practices of counterfeit cigarettes are unknown. Because toxic metals are incorporated into the tobacco lamina during cultivation, the ambient metal content of the soil could produce significant differences in metal levels in both the tobacco and smoke of counterfeit cigarettes. We compared mainstream smoke cadmium, thallium, and lead deliveries from counterfeit and authentic brands. Mainstream smoke levels of all three metals were far greater for counterfeit than the authentic brands, in some cases by an order of magnitude. Significant differences still existed even after normalizing mainstream smoke metal levels with nicotine delivery; the counterfeits typically delivered much higher levels of all three analytes. Our findings, based on 21 different counterfeit samples, suggest that counterfeit cigarettes potentially result in a markedly greater exposure to toxic heavy metals than authentic brands, even after correcting for differences in nicotine intake. In view of the unknown health risks associated with inhaling higher levels of toxic metals, it is prudent to minimize exposure to toxic substances whenever possible.

Introduction

Although smoking has declined in the United States over the last 20 years, 2004-based estimates indicate that 20.9% (44.5 million) of the US adult population are current smokers (CDC, 2005a). It has been suggested that cigarette smoking causes approximately 440,000 premature deaths per year and is the leading cause of preventable disease in the United States (CDC, 2002). Tobacco-related disease originates from the biological consequences of repeated inhalation exposure to numerous toxic constituents in cigarette smoke, which are produced by pyrosynthesis or liberated during combustion. Tobacco smoke has toxic (Chiba and Masironi, 1992, Stohs et al., 1997), genotoxic (Husgavfel-Pursiainen, 2004), mutagenic (Demarini, 2004), and carcinogenic properties (Eyre et al., 2004), and has been linked to adverse pregnancy outcomes (Källén, 1999, Lee, 1998, Little et al., 2004). There are five major classes of carcinogens in tobacco smoke (Fowles and Dybing, 2003). Some of these, such as tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons, have been carefully studied, contributing to a strong weight of evidence for associated health risks (Hecht, 1999), while toxic metals and metalloids constitute one of the more understudied major carcinogenic chemical classes in tobacco smoke. Cadmium and lead are present in tobacco smoke and contribute substantially to cancer risk indices (Fowles and Dybing, 2003). Cadmium is a Group I carcinogen and lead has recently been elevated from a Group IIB to a Group IIA carcinogen (IARC, 2004, Smith et al., 1997, Smith et al., 2003). Several metals, including cadmium, are also significant contributors to toxicological noncancer indices of health risks for respiratory and cardiovascular diseases such as peripheral artery disease (Fowles and Dybing, 2003, Navas-Acien et al., 2004). Thallium may be teratogenic at high levels (Hall, 1985, Léonard and Gerber, 1997, Mulkey and Oehme, 1993, Parker and Scheck, 1981). Monovalent thallium is known for its neurotoxicity (Mulkey and Oehme, 1993).

A cigarette’s design features influence smoke particulate mass transport through the tobacco rod and filter; thus cigarettes are characterized according to machine-smoked tar delivery categories described as full flavor, light, and ultralight. Published cadmium, thallium, and lead smoke levels and tar deliveries from a number of US cigarette brands demonstrate that mainstream smoke particulate heavy metal concentrations correlate well with filter ventilation designs (FTC, 2004, Pappas et al., 2006). Tobacco grown in soils with higher available cadmium and lead levels has correspondingly higher levels in the tobacco lamina (Adamu et al., 1989, Lugon-Moulin et al., 2006, Mulchi et al., 1992) and in the smoke particulate (Bache et al., 1985). Thus, cigarette brands with similar tar deliveries could yield markedly different smoke particulate levels of heavy metals depending on where the tobacco was grown and filter ventilation.

Historically, thallium content associated with agricultural products has been of limited concern because of its naturally low levels in the environment (Tremel and Mench, 1997). The few reported thallium levels in tobacco and mainstream smoke particulate were also low (Krivan et al., 1994, Pappas et al., 2006). However, mining and industrial activities in some areas have polluted agricultural irrigation water, resulting in dramatic increases for thallium and other metals in some agricultural products (Cheng, 2003, Xiao et al., 2004a, Xiao et al., 2004b). Because tobacco products originate from many different geographical areas, determining thallium levels has become more important.

Analyses of 47 counterfeit tobacco products seized in the UK from 2002 through early 2004 revealed that cadmium and lead levels were often markedly higher than in comparable domestic UK tobacco products. The metals in the counterfeit cigarettes were consistent with tobacco products grown with phosphatic fertilizer or possibly sludge as a soil amendment (Stephens et al., 2005), as has also been reportedly used for some tobacco crops produced in Tanzania (Semu and Singh, 1996).

The prevalence of counterfeit cigarettes in the United Kingdom in 2000–2001 was estimated at 5%. This estimate increased to 15% in 2003–2004 (HM Customs and Excise, 2003–2004). A US General Accounting Office (GAO) report cited Alcohol Tobacco and Firearms (ATF) and Bureau of Immigration and Customs Enforcement (ICE) investigations as evidence that smuggling of counterfeit cigarettes into the United States has become a significant problem, but stated further that no studies have been done to determine whether counterfeit cigarettes pose any additional health risks compared to genuine brand cigarettes (GAO, 2004). We therefore studied how selected toxic metal levels in mainstream smoke particulate from counterfeit cigarettes confiscated in the US compared to the corresponding authentic brands. We report the cadmium, thallium, and lead mainstream smoke particulate phase levels from 21 counterfeit cigarette samples confiscated in multiple seizures by the US Department of Homeland Security, the Bureau of Immigration and Customs Enforcement, and the Federal Bureau of Investigation. Because of high metal background in the smoke collection materials, we limited our analyses to three metals, excluding several other metals of interest after extensive acid leaching procedures failed to achieve sufficiently low blank levels.