Growth changes after inhalant abuse and toluene exposure: A systematic review and meta-analysis of human and animal studies

Inhalant abuse is a significant public health issue, particularly for adolescents, the predominant group of inhalant users. Adolescence is a critical growth period, and inhalant abuse has been associated with growth impairments, including reduced body weight and height. However, the extent to which inhalant abuse affects growth remains unquantified, and potential moderators remain unknown. To address this knowledge gap, a systematic review and meta-analysis of clinical human and preclinical animal studies utilizing toluene exposure (the primary solvent in abused products) was conducted. Five-hundred and sixty-nine studies were screened; 31 met inclusion criteria, yielding 64 toluene-control comparisons for body weight and 6 comparisons for height. Toluene exposure was negatively associated with body weight (d = -0.73) and height (d = -0.69). Concentration of inhaled toluene, but not duration, moderated the effect of toluene exposure on body weight, with more severe impairments at higher concentrations. Differences in effect size for body weight were observed for study characteristic subgroups including sex, age at first exposure, administration route and species. However, these findings should be interpreted cautiously due to low study numbers. Growth impairments, particularly during adolescence, can cause long-term health consequences. These effects on growth are therefore an important clinical outcome for individuals with a history of inhalant abuse.