Indoor exposure to heavy metals poses human health risks worldwide, but study reports from Thailand are still limited, particularly in rural and urban areas. We measured the heavy metals in a hundred indoor household dust samples collected from urban and rural areas in Chiang Mai and Lamphun provinces and found a significantly higher concentration of As in rural areas and Cd in urban areas with industrial activities. The source identification of the heavy metals showed significant enrichment from traffic emissions, paint, smoking, and mixed sources with natural soil. From health risk assessment models, children were more vulnerable to noncarcinogenic risks (HI = 1.45), primarily via ingestion (HQ = 1.39). Lifetime cancer risks (LCRs) due to heavy metal exposure were found in adults (LCR = 5.31 × 10⁻⁴) and children (LCR = 9.05 × 10⁻⁴). The cancer risks from As were higher in rural areas via ingestion, while Cr and Ni were higher in urban areas via inhalation and ingestion, respectively. This study estimated that approximately 5 out of 10,000 adults and 9 out of 10,000 children among the population may develop cancer in their lifetime from exposure to indoor heavy metals in this region.

Gymnema inodorum (Lour.) Decne is a vegetable local to Chiang Mai Province of Northern Thailand. This study aimed to analyze the antioxidant and phytochemical potential of G. inodorum found in Chiang Mai Province; antioxidant compounds of G. inodorum were tested via DPPH, ABTS and FRAP assays, and total phenolic compound and total flavonoid contents were analyzed. Anti-inflammatory effects were focused on regarding pharmacological potential. The gymnemic acid level was analyzed by HPLC-UV, and other potential chemicals were analyzed by LC-QTOF/MS. The quantifications of gymnemic acid contents analyzed using HPLC-UV showed that the highest gymnemic acid concentrations were found in the air-dried and roasted 1-day-fermented leaf extracts (0.1258 ± 0.0157 μg/mg). The highest free radical scavenging activity via DPPH assay was found in baked leaf extract, with an IC₅₀ of 8.99 mg/mL, and via ABTS assay in baked and roasted leaf extracts, with an IC₅₀ of 1.05 mg/mL. FRAP assays showed the highest free radical scavenging activity for the baked leaf extract, with 0.0085 ± 0.008 mM Fe²⁺/g sample. The total phenolic contents of fresh G. inodorum leaf extracts obtained with ethanol, methanol and water were 0.19 ± 0.0004, 0.21 ± 0.0010 and 0.10 ± 0.0008 μg GAE/g, respectively. The total flavonoid contents of fresh G. inodorum leaf extracts obtained with ethanol, methanol and water were 74.56 ± 28.00, 71.88 ± 16.11 and 10.74 ± 3.63 μg QE/g, respectively. The LC-QTOF/MS analysis of the fresh G. inodorum leaf extract showed that 6-hydroxykaempferol 7-rutinoside was the most abundant compound. In the study, G. inodorum, a plant local to Northern Thailand, is shown to be a useful plant with high antioxidant and phytochemical potential properties.