Mass transfer of an organophosphate flame retardant between product source and dust in direct contact

Organophosphate flame retardants(OPFRs)are a group of semi-volatile organic compounds(SVOCs)and among the most abundant contaminants indoors.Their indoor presence has been associated with potential health risks however there is limited understanding as to how they are released from indoor sources.This study uses an emission micro-chamber to explore one of the currently understudied chemical migration pathways;direct transfer between a source material and settled dust in contact with the source.A tris(2-chloroisopropyl)phosphate(TCIPP)-treated insulation board is used as the source material.Rapid and substantial transfer was observed after only 8 h of source-dust contact,resulting in 80 times higher concentrations in dust compared to pre-experiment levels.Further time points at 24 h and 7 d showed similarly high average dust levels and the TCIPP in the dust and air in the chamber was calculated to be close to thermodynamic equilibrium.It was concluded that TCIPP was effectively transferred from the insulation board to the dust on its surface and the surrounding air via gas-phase diffusion.In a real room,a gradient of TCIPP concentrations in air above the surface of a product could result in higher concentrations in dust sitting on the product than dust in the rest of the room.

Sampling strategy for estimating human exposure pathways to consumer chemicals

Human exposure to consumer chemicals has become a worldwide concern.In this work,a comprehensive sampling strategy is presented,to our knowledge being the first to study all relevant exposure pathways in a single cohort using multiple methods for assessment of exposure from each exposure pathway.The selected groups of chemicals to be studied are consumer chemicals whose production and use are currently in a state of transition and are;per-and polyfluorinated alkyl substances(PFASs),traditional and“emerging”brominated flame retardants(BFRs and EBFRs),organophosphate esters(OPEs)and phthalate esters(PEs).Information about human exposure to these contaminants is needed due to existing data gaps on human exposure intakes from multiple exposure pathways and relationships between internal and external exposure.Indoor environment,food and biological samples were collected from 61 participants and their households in the Oslo area(Norway)on two consecutive days,during winter 2013-14.Air,dust,hand wipes,and duplicate diet(food and drink)samples were collected as indicators of external exposure,and blood,urine,blood spots,hair,nails and saliva as indicators of internal exposure.A food diary,food frequency questionnaire(FFQ)and indoor environment questionnaire were also implemented.Approximately 2000 samples were collected in total and participant views on their experiences of this campaign were collected via questionnaire.While 91%of our participants were positive about future participation in a similar project,some tasks were viewed as problematic.Completing the food diary and collection of duplicate food/drink portions were the tasksmost frequent reported as“hard”/“very hard”.Nevertheless,a strong positive correlation between the reported total mass of food/drinks in the food record and the total weight of the food/drinks in the collection bottles was observed,being an indication of accurate performance of the participants despite the challenges of the sampling campaign.

Water-to-air transfer of branched and linear PFOA:Influence of pH,concentration and water type

The volatilisation of perfluorooctanoic acid(PFOA)was measured experimentally at a range of pH values using a previously published laboratory method.Water-to-air transfer was studied for five structural isomers,namely:the linear isomer(n-PFOA)and the four most commonly occurring branched isomers(3-,4-,5-and 6-PFOA).The influence of water concentration and water type on the pH-dependent waterto-air transfer was also investigated for n-PFOA.The water-to-air transfer was studied over the course of 48 h at pH values ranging from 0.2 to 5.5.Under all experimental conditions tested,the volatilisation of PFOA was negligible at pH>2.5.In experiments performed with MilliQ water,volatilisation increased with decreasing water pH.In experiments performed with tap water and lake water,maximum volatilisation was observed at pH 1.The concentration of PFOA in water had no influence on the pH value at which water-to-air transfer was observed(i.e.at pH<2.5)for the concentration range tested(0.1e50 mg/L PFOA in deionised water).Although the percentage of PFOA volatilised was significantly different for the four branched isomers at low pH,volatilisation was not observed above pH 2.5 for any branched isomer suggesting that all PFOA isomers have a low pKa.Overall,these laboratory results demonstrate that volatilisation of any structural isomer of PFOA from water is negligible at environmentally-relevant conditions.It is unlikely that PFOA isomers will be fractionated in the environment as a result of volatilisation because it is a process of negligible environmental relevance.