Research News
Toxic Metals in Fine Dust Pose Health Risks Across Thai Cities, Study Finds
A new study has quantified the non-carcinogenic and carcinogenic risks associated with inhaling PM2.5-bound toxic metals in five provinces surrounding Bangkok, Thailand, from December 2020 to December 2021. This comprehensive analysis, which utilized Monte Carlo simulations across four age groups, highlights significant public health concerns and calls for stricter air quality regulations.
Key findings from the study include:
Higher PM2.5 Concentrations: Provinces with higher factory densities and during haze periods experienced significantly higher PM2.5 concentrations.
Acceptable Non-Carcinogenic Risks: While non-carcinogenic risks (Hazard Index values) were below the acceptable threshold of 1 for all age groups and provinces, indicating no significant risk of chronic effects, the carcinogenic risks presented a different picture.
Increased Cancer Risk: The carcinogenic risks from PM2.5-bound metals ranged from 7.08 x 10^-7 to 4.29 x 10^-6, indicating an increased risk of cancer for preschool children and adults. The cancer risk was highest in industrial areas (Samut Prakan and Samut Sakhon), followed by areas with dense traffic (Nonthaburi and Pathum Thani), and lowest in agricultural areas (Nakhon Pathom).
Key Carcinogenic Metals: Chromium (Cr) and Arsenic (As) were identified as the main contributors to cancer risk from PM2.5 inhalation. Other metals like Nickel (Ni), Cobalt (Co), and Vanadium (V) also contributed significantly in specific areas or age groups.
Vulnerable Populations: Preschool children and adults showed the highest cancer risks due to early-life exposure and longer cumulative exposure time, respectively.
Inadequate Regulations: Thailand current air quality regulations, which primarily limit only lead (Pb), are insufficient given the high carcinogenic potential of other metals. The study highlights that Pb concentrations were below Thailand's air quality standard, yet other toxic metals posed significant cancer risks.
Benefits of Stricter Standards: Adopting the 2021 World Health Organization (WHO) 24-hour PM2.5 standard of 15 µg/m³ could decrease cancer risk by 17.89–43.18%. Even lowering the standard to 25 µg/m³ would result in a 9.63–29.62% decrease in cancer risk.
These findings underscore the urgent need for updated air quality policies in Thailand to include comprehensive regulations for various toxic metals to better protect public health, particularly in vulnerable populations and industrial areas.
Council of Thailand grant number [NR. WorPorSor 76/2563]
Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University
Email: wiroj.j@chula.ac.th