Associations between Cigarette Smoking and Total Mortality Differ Depending on Serum Concentrations of Persistent Organic Pollutants among the Elderly

Abstract

There are substantial variations of relative risks (RR) in smoking-related mortality by country and time. We hypothesized the RRs in smoking-related mortality might differ depending on serum concentrations of persistent organic pollutants (POPs). We evaluated the associations of cigarette smoking with total mortality in 610 elderly (aged ≥ 70 yr) (702 elderly for organochlorine pesticides [OCPs]) after stratification by serum concentration of POPs, in the National Health and Nutrition Examination Survey (NHANES) 1999-2004 followed through 2006. Summary measures of POPs subclasses showed significant or marginally significant interaction with cigarette smoking on the risk of total mortality. P values for interaction were 0.069 for polychlorinated dibenzo-p-dioxins (PCDDs), 0.008 for polychlorinated biphenyls (PCBs), and 0.024 for OCPs. The effect of smoking on total mortality showed different patterns according to the serum concentration of some POPs. Former or current smokers had 1.4 to 2.9 times higher mortality rates compared with never smokers among participants with higher serum concentrations of POPs (2nd or 3rd tertiles). However, when the level of PCBs or OCPs were low (1st tertile), there were little positive associations between smoking and mortality. Our study suggests that the background exposure to several POPs may be related to variability in smoking-related total mortality.

Persistent organic pollutants and mortality in the United States, NHANES 1999–2011

“…While not statistically significantly in our analyses, the suggestion of greater mortality among overweight and obese individuals with high OC pesticide exposure is opposite than reported previously. [ 41 , 68 ] Conversely, while we did not observe significant effect modification by ACR, our point estimates were often consistent with the prior report of greater mortality among those with high ACR and high OC pesticide exposure [ 69 ] or among current smokers with high OC pesticide exposure [ 70 ]. The suggestion that sex modifies the OC pesticide other-cause mortality association is potentially plausible given potential endocrine-disruption related effects of exposure [ 71 ], but requires further confirmation in other samples.…”

“…This limited our ability to detect small effect and our ability to further investigate the association with more refined cause-specific mortality categories. Similarly, although motivated by evidence of effect modification in other settings [ 34 , 68 – 70 ], we consider our analyses of effect modification to be exploratory given our small sample. Future work in larger samples will be required to examine the effect of exposure within potentially susceptible sub-populations.…”

Associations between persistent organic pollutants, type 2 diabetes, diabetic nephropathy and mortality

“…To our knowledge, this is the first study to link POPs contamination with ESRD and death among persons with type 2 diabetes. Previous studies showed early mortality with POPs exposure, particularly due to an increased risk of breast and pancreatic cancers [16, 17, 43].…”

“…A study of kidney biopsies in the arctic fox found a wide range of kidney tissue damage associated with exposure [15], but this association has not been studied in humans. POPs are also associated with early mortality in the elderly and in cigarette smokers [16–17].…”

Human Elimination of Organochlorine Pesticides: Blood, Urine, and Sweat Study

“…In addition, exposure to OCPs in combination with other pollutants, like inorganic toxic elements, may facilitate an additive or synergistic effect [ 15 ]. An interesting study of 702 adults over the age of 70 years, for example, reported significantly higher mortality levels in smokers in the 2nd or 3rd tertile of OCP blood levels but not among smokers in the lowest tertile of exposure [ 16 ].…”