Phthalates exposure and longitudinal trajectories of body composition and regional fat distribution in children: shifting towards "apple-shaped" body and the role of physical activity.

Mono-n-butyl phthalate (MnBP) exposure was significantly associated with the 'largest' trajectory of fat mass index, body fat percentage, and fat-free mass index in children.

• MnBP exposure showed ORs of 1.69, 1.70, and 2.17 for the 'largest' trajectories of FMI, BF%, and FFMI respectively (P < 0.05)
• Study tracked 519 children starting at mean age 8.62 years in Xiamen city, China from May 2017 to October 2020
• PAE metabolites were measured at baseline and body composition was assessed through bioelectrical impedance analysis at six visits
• Group-based trajectory modeling and multinomial logistic regressions were used to examine how PAE exposure influenced body composition trajectories

Mono-iso-butyl phthalate (MiBP) exposure was negatively associated with the 'largest' trajectory of lean mass in children.

• MiBP exposure was associated with the 'largest' lean mass trajectory with OR = 0.51 (95% CI = 0.28, 0.93)
• This negative association suggests that MiBP exposure may reduce lean mass accumulation over time
• The finding contrasts with other phthalate metabolites that were positively associated with fat-related trajectories

Most PAE metabolites were significantly associated with the 'largest' trajectory of body fat percentage in the trunk and upper limbs, suggesting a shift toward an 'apple-shaped' body.

• Significant associations were found between most PAE metabolites and the 'largest' trajectory of BF% in the trunk and upper limbs (P < 0.05)
• The pattern of fat accumulation in the trunk and upper limbs rather than lower limbs characterizes the 'apple-shaped' body distribution
• Generalized estimating equations were used for the relationship between PAEs and repeated body composition measurements across six visits

Moderate-to-high physical activity moderated the association between mono-2-ethylhexyl phthalate (MEHP) exposure and bone mineral density trajectories.

• Moderate-to-high physical activity relieved the increased BMD trajectories caused by MEHP exposure (P for interaction = 0.023)
• Stratified analysis with an interaction term was used to investigate how physical activity influences the relationships between PAEs and body composition
• Physical activity also decreased regional BF% in the trunk and upper limbs

PAE metabolites were measured at baseline in a longitudinal child growth and development cohort followed over approximately three and a half years.

• 519 children were tracked in the cohort from May 2017 to October 2020 in Xiamen city, China
• Mean age of children at baseline was 8.62 years
• Body composition was assessed through bioelectrical impedance analysis at six visits over the follow-up period
• PAE metabolites were measured only at the outset of the study

PAEs exposure was associated with larger trajectories of fat mass and bone mineral density alongside a smaller lean mass trajectory over the study period.

• The combination of increased fat mass, BF%, and BMD trajectories with decreased LM trajectory was observed in association with PAE exposure
• These longitudinal body composition changes were assessed across six measurement visits spanning approximately 3.5 years
• The effects were observed in children starting at a mean age of 8.62 years, a critical period for growth and development