Human hair has increasingly been used as a noninvasive biomonitoring matrix for assessment of human exposure to various organic contaminants (OCs). However, the accumulation processes of OCs in hair remains unclear thus far, which raised concerns on the reliability of hair analysis results for OCs. Herein, Chinese population was selected as the study subject, the effects of changes in hair biological characteristics, including length and color, on the accumulation of OCs in hair was investigated. With the growing of hair shaft and the increased distance from the scalp, a significant increasing trend was found for levels of polychlorinated biphenyls (PCBs) and organophosphate flame retardants (PFRs) along the hair shafts (p < 0.05). Source identification using Chemical Mass Balance model indicated that PCBs in hair were mainly from exogenous sources (air and dust). The accumulation rates of PCB and PFR individuals in the hair shaft decreased with increasing of log K ow values. Additionally, the levels of OCs in hair decreased with the change in color from black to white, probably because of the loss of melanin in white hair. The ratios (R) of C black /C white were significantly correlated with the log K ow values for individual chemicals (p < 0.05), implying that OCs with high log K ow values tend to accumulate more readily in black hair. The results of this study demonstrated the growth and change in colors of hair, as well as the physicochemical properties of chemicals, play vital roles in the accumulation of OCs in hair. The present study provides fundamental basis for the precise assessment of human exposure to OCs using hair as a biomonitoring matrix in future studies. [Display omitted] • Levels of PCBs and PFRs increased along the hair shafts. • External sources dominated the levels of PCBs in hair segments. • The accumulation rates of PCBs and PFRs in hair decreased with increase of log K ow s. • Hair levels of organic contaminants decreased with the change from black to white. [ABSTRACT FROM AUTHOR]