This study addresses the comparative influence of physicochemical parameters on the dissolution of Pb and its levels in the groundwater of former Pb mining areas in Kabwe and non-mining areas in Lusaka, Zambia. This cross-sectional study analyzed 61 groundwater samples from hand pump boreholes using atomic absorption spectrometry. Physicochemical parameters were measured, including electrical conductivity (EC), temperature, total dissolved solids (TDS), and pH. Statistical analysis involved the Wilcoxon test, Spearman’s correlation, robust linear regression, Principal component analysis (PCA), and generalized additive models. Pb concentrations were particularly higher (p = 0.029; median = 0.131 mg/L) in mining areas compared to non-mining areas (median = 0.071 mg/L). The EC in the mining areas (median = 585 µS/cm) was significantly (p = 0.001) lower than those in the non-mining area (median = 1100 µS/cm). Likewise, TDS levels revealed a significant (p = 0.001) difference between the mining area (median = 303 ppm) and the non-mining area (median = 601 ppm). The median pH values for groundwater samples in the mining and non-mining areas were 6.96 and 7.27, respectively. Spearman’s rank correlation revealed a significant (rho = − 0.405; p = 0.036) inverse relationship between Pb concentrations and pH in non-mining areas. Robust linear regression and generalized additive models underscored a significant (p = 0.016) non-linear relationship between temperature and Pb across all areas, with the non-mining area demonstrating a significant (p = 0.003) non-linear relationship between temperature and pH concerning Pb. The study associates mining activities with increased Pb concentrations, underscoring it as a principal contamination source. In contrast, elemental dissolutions from the basement limestone with dolomite might increase Pb concentration in the non-mining areas. The observed positive relationship between temperature and pH in non-mining areas highlights its positive interactions with Pb mobility while temperature greatly influences Pb dissolutions in mining areas.

Introduction: Polysubstance use—use of more than one substance—is prevalent and an emergent public health issue. Yet not much is known about factors associated with same-day polysubstance use among adolescents. This study examined correlates of same-day tobacco and cannabis use/co-use among adolescents who use tobacco/cannabis. Methods: Cross-sectional data were from 10th and 11th grade students (n = 536) who reported tobacco/cannabis use. Regression models were used to examine intrapersonal, psychological (anxiety, depression), societal (societal concern, discrimination), and environmental (public and home secondhand smoke/vape exposure) correlates of past 30-day usage frequency (no, infrequent, and frequent use) of same-day: poly-product use (poly-tobacco/nicotine [use of different types of nicotine/tobacco]; poly-cannabis [use of different types of or marijuana/tetrahydrocannabinol (THC)]); poly-drug use [tobacco/nicotine and marijuana/THC], and nicotine and THC vape mixing. Results: Participants were predominantly Hispanic (66.23%) and male (62.50%). Among participants, 8.58%, reported frequent same-day poly-tobacco use, 13.81% frequent same-day poly-cannabis use, 13.25% frequent same-day poly-drug use, and 3.36% vape mixing. Past 30-day alcohol use was associated with higher odds (1.88–8.31, p<.05) of infrequent and frequent same day use of all study outcomes except vape mixing. Secondhand smoke/vapor exposure was consistently associated with higher odds (1.13–1.26, p < .05) of infrequent/frequent same day use. Discrimination increased the odds of some same-day polysubstance use while societal concerns had inconsistent effects across study outcomes. Conclusion: A significant proportion of adolescents who use tobacco/cannabis products might engage in high-risk use patterns. Alcohol use, societal, and environmental factors significantly increase the likelihood of same-day poly-use of tobacco and cannabis products. Implications: Frequent same-day poly-product/drug use is common among adolescents who use tobacco and/or cannabis. Alcohol use, societal concerns, and environmental exposure to secondhand smoke/vape are significant contributors to same-day poly-product/drug use and nicotine and marijuana/THC vape mixing among these adolescents. Findings suggest that while infrequent same-day poly-product/drug use may be more opportunistic and situation-dependent, often occurring in contexts where alcohol is present, frequent use may be more influenced by social contexts and environmental cues. Understanding these complex relationships between substances and high-risk use patterns is crucial for developing effective prevention strategies and treatment approaches for poly-drug use disorders.