Description
Indoor pollution due to house dust is well recognized. House dust is an extremely complex and heterogeneous mixture of biological material, deposited indoor aerosols, fibers, minerals and soil particles brought in the house by foot traffic. Human exposure to house dust can cause significant health risk especially to young children due to their behaviors such as crawling and playing on dusty floors and hand to mouth behavior. Previous studies have shown the presence of smoke residues, pesticides, PAHs, PCBs, flame retardants, heavy metals and asbestos in house dust by using conventional targeted analytical methods like gas chromatography (GC) or liquid chromatography (LC) coupled with mass spectrometry (MS). These methods analyze the presence of only certain organic chemicals as targeted analytes, while leaving the other organic chemicals present unrecognized. Some studies have used effect-directed bio-assays which is a part of non-targeted analytical approach to detected toxicity of these unrecognized organic chemicals present in house dust. Effect directed bio-assays show the toxicity of the house dust chemicals, but still do not characterize the specific organic chemicals present in the house dust responsible for the toxicity. Here we have used a mass spectroscopy-based non-targeted analytical approach to simultaneously analyze known (targeted) and unknown (non-targeted) compounds present in house dust. We used comprehensive two dimensional gas chromatography coupled with time of flight mass spectrometry (GC_GC/TOF-MS) to analyze a composite house dust collected from 69 houses in San Diego county. We have recorded the presence of 8115 peaks using dispersive Solid Phase Extraction (DSPE) and 9081 peaks without using any silica Solid Phase Extraction (SPE). We determined the presence of 1011 chemicals by using the DSPE and 1094 chemicals without using any silica SPE. We chose some those chemicals likely to pose a potential health hazard to humans, especially children, and characterized them further for their toxicity and current regulation for household uses. For the first time, we discovered in this house dust sample the presence of a wide range of organic chemicals not previously recognized, including tobacco smoke products, pesticides, household/personal care products, industrial chemicals and well known recreational drugs. Many of these chemicals are highly toxic and can cause serious health problems in humans. However, only a few of them are regulated for their indoor uses. There is a need for improved risk assessment of house dust exposure to children's health considering the fact that house dust contains many toxic organic chemicals which were not recognized in previous studies.
