## 3 Results and Discussion
### Assessments of Carcinogenic and Non-Carcinogenic Risks  
To safeguard human health and the safety of the public, it is essential to assess the potential risk for TE exposure. TE is necessary for many biological functions, but it may also be harmful to people's health, especially if the TE concentrations in the surrounding living environment exceed certain thresholds. USEPA which based its recommendations on rigorous scientific criteria with the Regional Screening Level (RSL) [37], plays a significant role in establishing guidelines for assessing TE threats. This study assesses the carcinogenic and non-carcinogenic risks associated with exposure to TE in the study area.  
To assess the risk of cancer to human health associated with exposure to TE, two approaches were used and three specific TEs were considered such as chromium, cobalt, and nickel. The ways of exposure used were inhalation and ingestion. No dermal exposure was observed in this study. According to the USEPA guidelines [37], the inhalation risk for residents in the study area is low and is 7.01 \(\times\) 10\({}^{-6}\), while the ingestion risk is moderate (3.73 \(\times\) 10\({}^{-4}\)). The cancer risk for these residents is also moderate (3.8 \(\times\) 10\({}^{-4}\)). Table 9 shows the various carcinogenic risks associated with exposure to TE. The carcinogenic risk for cobalt and nickel in this study is lower than that estimated by [PERSON] et al. in the cobalt-nickel region of Lomie [8]. This difference could be attributed to the fact that the mining area in Lomie has already been exploited, leading to increased contamination of the soil and environment.  
\begin{table}
\begin{tabular}{l l l l l l l l l l l l l l l l} \hline
**TE** & **Ba** & **Cr** & **Mn** & **Fe** & **Co** & **Ni** & **Cu** & **Zn** & **Ga** & **Pb** & **Zr** & **Y** & **Sn** & **Br** & **Ti** & **V** & **Nb** \\ \hline Ba & 1.00 & & & & & & & & & & & & & & & & \\ Cr & 0.27 & 1.00 & & & & & & & & & & & & & & & \\ Mn & 0.46 \({}^{*}\) & 0.09 & 1.00 & & & &  
The non-carcinogenic risk to children and adults from the ingestion and inhalation of trace elements, including Ba, Cr, Co, Cu, Fe, Rb, Sr, Zn, and Zr, is presented in Table 10. The average daily dose for each method is calculated, with ingestion typically resulting in a higher dose for children (106) than inhalation (8.86 \(\times\) 10\({}^{-4}\)). The non-carcinogenic risk value exceeding 106 indicates trace element pollution, posing a health risk to children [67]. According to [PERSON] et al. [31], this high level highlights the non-carcinogenic risk in this study area. Adults also show a non-carcinogenic risk value above 1 (9.9), with ingestion being riskier than inhalation. These findings indicate that exposure to trace elements like Ba, Cr, Co, Cu, Fe, Rb, Sn, Zn, and Zr can cause various health effects, particularly gastrointestinal, respiratory, and cardiac issues, especially with chronic exposure [42; 49; 50; 51]. The particularly high risk associated with zirconium in this study could suggest a specific industrial or mining pollution source in the area, requiring further assessment to identify and manage this source to limit human exposure. Children are especially vulnerable to environmental hazards due to their biological development, limiting their ability to metabolize, detoxify, and eliminate contaminants.