Serum cotinine cut-points for secondhand smoke exposure assessment in children under 5 years: A systemic review

Abstract

Background Serum cotinine has become the most widely used biomarker of secondhand smoke exposure (SHS) over time in all ages. The aim of this study was to review the serum cotinine cut-points used to classify children under 5 years as exposed to SHS. Methods A systematic review performed in the Pubmed (MEDLINE) and EMBASE databases up to April 2021 was conducted using as key words "serum cotinine", “tobacco smoke pollution” (MeSH), "secondhand smoke", "environmental tobacco smoke" and “tobacco smoke exposure”. Papers which assessed SHS exposure among children younger than 5 years old were included. The PRISMA 2020 guidelines were followed. Analysis was pre-registered in PROSPERO (registration number: CRD42021251263). Results 247 articles were identified and 51 fulfilled inclusion criteria. The selected studies were published between 1985–2020. Most of them included adolescents and adults. Only three assessed postnatal exposure exclusively among children under 5 years. None of the selected studies proposed age-specific cut-points for children < 5 years old. Cut-point values to assess SHS exposure ranged from 0.015 to 100 ng/ml. The most commonly used cut-point was 0.05 ng/ml, derived from the assay limit of detection used by the National Health and Nutrition Examination Survey (NHANES). Conclusions No studies have calculated serum cotinine age-specific cut-points to ascertained SHS exposure among children under 5 years old. Children’s age-specific cut-points are warranted for health research and public health purposes aimed at accurately estimating the prevalence of SHS exposure and attributable burden of disease to such exposure, and at reinforcing 100% smoke-free policies worldwide, both in homes, private vehicles and public places.

Saliva and Exhaled Breath Condensate Correlate With Serum in 4-12-Year-Olds Exposed to Secondhand Electronic Cigarette Vapors: A Pilot Study

“…Major metabolites of nicotine like cotinine or 4-(methylnitrosoamino)-(3-pyridyl)1-butanol (NNAL) are considered to be the best biomarkers of secondhand conventional smoking exposure and are most commonly measured in serum (Jeong et al, 2021; Mourino et al, 2022). Because of this and because blood is generally regarded as the best body fluid for evaluation of systemic processes (Williamson et al, 2012), the first step in our study was to determine if non-invasively accessed matrices like saliva or exhaled breath might reflect a similar array of metabolites as what is identified in blood.…”

Tobacco Smoke Exposure in Pregnant Dogs: Maternal and Newborn Cotinine Levels: A Pilot Study

“…With regard to the clinical effects of smoke exposure in pregnant bitches, no correlation was found with respect to the parameters considered, that is, maternal age, body weight, litter size, neonatal mortality, and malformations. The literature is conflicting about the impact of age on cotinine concentration in adult smokers [ 44 ], while young children seem to have higher levels than older/adolescents, possibly due to differences in cotinine metabolism and clearance [ 45 ]. In agreement with studies in humans and rats [ 46 , 47 , 48 ], we did not find correlations between cotinine concentration in any matrices and body weight and litter size.…”

Association of chronic cough with exposure to polycyclic aromatic hydrocarbons in the US population

“…Covariates were selected based on prior epidemiological research that has examined associations between pollutant exposure and chronic cough [ 22 ]. Covariates included in this study were sex (male/female), age group (20–59 and ≥ 60 years), race (Mexican American, other Hispanic, non-Hispanic white, non-Hispanic black, other race), marital status (unmarried, separated, married), body mass index (BMI), educational attainment (lower than high school, high school or equivalent, above high school), household poverty-to-income ratio (PIR), alcohol (drinking at least 12 times per year), hypertension, and serum cotinine concentrations (markers of environmental tobacco smoke (ETS) exposure with a cut-off point of 0.05 ng/mL) [ 23 ]. Additionally, we accounted for the primary risk factors for chronic cough, specifically chronic bronchitis and asthma [ 3 ].…”