TSNA exposure from cigarette smoking: 18Â Years of urinary NNAL excretion data

- We gathered published data of urinary NNAL excretion among cigarette smokers.
- The data suggest TSNA exposure has declined among cigarette smokers over the past 18 years.
- The decline in TSNA exposure is not explained by a decline in cigarettes smoked per day.
- These findings are consistent with reductions in cigarette tobacco and smoke TSNA levels.

The objective of this work was to characterize trends over time in urinary excretion of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) among cigarette smokers in the US. We identified 35 studies presenting data that either reported, or could be converted to, common units of total urinary NNAL excretion as pmol/mg creatinine. The studies spanned 18 years, reported urinary NNAL excretion estimates for 61 defined populations, and included a combined total of 3941 study participants. Analyses show that urinary NNAL excretion trends downward with study publication year, and the trend is statistically significant. The trend does not appear to be accounted for by a reduction in cigarettes smoked per day by study participants over the same time period. This trend is consistent with reductions in tobacco specific nitrosamine (TSNA) levels in both cigarette tobacco filler and mainstream cigarette smoke observed over the past decade and with efforts by the tobacco industry and the agricultural community to reduce levels of TSNAs in tobacco and cigarette smoke.