Third-hand exposure at homes: Assessment using salivary cotinine

Area of Science:

• Environmental Health
• Toxicology
• Public Health

Background:

• Secondhand smoke (SHS) is a known health hazard.
• Thirdhand smoke (THS) exposure, the residue from tobacco smoke, is less understood.
• Investigating THS exposure markers is essential for comprehensive tobacco control.

Purpose of the Study:

• To quantify salivary cotinine levels in non-smokers exposed to SHS and THS at home.
• To compare cotinine concentrations across different passive smoke exposure scenarios.
• To inform public health strategies regarding THS risks.

Main Methods:

• Cross-sectional study of 519 non-smokers in Barcelona.
• Saliva samples collected for cotinine analysis.
• Questionnaire assessed self-reported SHS and THS exposure at home.

Main Results:

• Individuals exposed to THS (with or without SHS) had significantly higher salivary cotinine levels than unexposed individuals.
• THS-only exposure showed a 106% increase in cotinine.
• No significant difference in cotinine levels was found between SHS+THS and THS-only exposure groups.

Conclusions:

• Thirdhand smoke exposure results in detectable cotinine in saliva.
• THS exposure poses a quantifiable risk comparable to SHS exposure.
• Public health policies must address THS reduction in homes.