This study presents an improved and validated method for quantitatively analyzing six high-production volume polymers (PE, PET, PVC, PMMA, PP, and PS) in human whole blood samples using pyrolysis-gas chromatography–mass spectrometry (Py-GC-MS). The method includes stringent quality assurance and control procedures, such as the use of quality control samples and continuous monitoring of batch analyses. The optimized Py-GC-MS conditions enhance method sensitivity and selectivity. Recovery experiments demonstrated high accuracy and precision, with values ranging from 68 to 109% for quality control samples. The method was applied to 68 whole blood samples, identifying plastic polymers in 64 samples, with PE being the predominant polymer followed by PVC, PET, and PMMA. In 17 blood samples, polymer concentrations exceeded the limit of quantitation, with a mean of 1070 ng/mL for the summed polymer concentrations, ranging from 170 to 2490 ng/mL. The mean of the sum of polymers across all blood samples was 268 ng/mL. These findings highlight the need for further research to comprehensively quantify micro and nanoplastics (MNPs) in human matrices, considering their potential health implications.This study presents an improved and validated method for quantitatively analyzing six high-production volume polymers (PE, PET, PVC, PMMA, PP, and PS) in human whole blood samples using pyrolysis-gas chromatography–mass spectrometry (Py-GC-MS). The method includes stringent quality assurance and control procedures, such as the use of quality control samples and continuous monitoring of batch analyses. The optimized Py-GC-MS conditions enhance method sensitivity and selectivity. Recovery experiments demonstrated high accuracy and precision, with values ranging from 68 to 109% for quality control samples. The method was applied to 68 whole blood samples, identifying plastic polymers in 64 samples, with PE being the predominant polymer followed by PVC, PET, and PMMA. In 17 blood samples, polymer concentrations exceeded the limit of quantitation, with a mean of 1070 ng/mL for the summed polymer concentrations, ranging from 170 to 2490 ng/mL. The mean of the sum of polymers across all blood samples was 268 ng/mL. These findings highlight the need for further research to comprehensively quantify micro and nanoplastics (MNPs) in human matrices, considering their potential health implications.