Association between coastal residence since birth and blood pressure among adolescents: a cross-sectional comparative study

Background Salinity intrusion in coastal Bangladesh poses significant public health challenges, with millions exposed to elevated sodium through drinking water. While dietary salt intake is a well-established risk factor for hypertension, the impact of environmental salinity exposure on blood pressure in adolescents remains poorly understood. This study examined the association between coastal residence since birth and blood pressure among school-going adolescents in Bangladesh. Methods This cross-sectional comparative study was conducted between January and December 2014 among 1,056 adolescents residing in high-salinity (Dacope, Khulna) and low-salinity (Singair, Manikganj) areas since birth. Blood pressure measurements, anthropometric data, and information on sociodemographics, drinking water sources, dietary salt intake, family history of hypertension, and physical activity were collected. Linear regression analysis examined the effect of residence on blood pressure after adjusting for age, sex, family history of hypertension, extra salt intake, BMI, and physical activity level. Results Participants had an average age of 14.95{+/-}0.78 years, and 66.76% were male. Those living in high-salinity areas had significantly lower BMI (17.58{+/-}2.14 vs 22.56{+/-}1.46 kg/m2), higher underweight prevalence (23.67% vs 0.19%), and predominantly used pond water (60.98%) compared to deep tubewells (86.17%) in low-salinity areas. After adjustment for confounders, residence in high-salinity areas since birth was independently associated with an 8.74 mmHg increase in systolic blood pressure (95% CI: 7.22 to 10.26, p<0.001) but showed no significant association with diastolic blood pressure ({beta}=-0.97 mmHg, 95% CI: -2.18 to 0.25, p=0.120). Sensitivity analysis using median quintile regression confirmed these findings. Conclusion Coastal residence since birth is independently associated with elevated systolic blood pressure in adolescents, highlighting a potential risk factor of hypertension in coastal populations.