7. Limitations of the study

The XRF was used as essentially a screening tool for the presence of BFRs but was also invaluable to help quantify the total amount of the various BDEs present in the consumer products when BDEs were the only brominated compounds present. While there is some positive evidence of a correlation between the total BDE calculated from the laboratory results and the XRF reading there are a number of assumptions made;

  1. As discussed the XRF does not identify the actual BFRs yet if bromine was detected by the XRF it was assumed to be a BDE unless the laboratory analysis stated otherwise. Hence for further study samples should be taken from all products that contain a BFR as identified by the XRF so as to ascertain if/which BDEs are present.
  2. The quantity of bromine varies by mass between 65.8 % in tetrabromodiphenylether to 83.3% in decabromodiphenyl ether (75% mean value if equal amounts of the BDEs). Hence in calculating the total BDE concentration from the XRF value an averaged value was used and not the accurate values for the particular BDEs present. If laboratory analysis is carried out on all samples then there is no need to attempt to quantify the amount of BDE using the XRF.
  3. While a large number of products were analysed with the XRF it was not feasible due to time constraints and the limitation of this study to analyse all the different models and types of product in all the different retail stores. In addition, almost all products tested showed different bromine levels in different parts even when these look similar As a result the XRF readings obtained are reflective of the kind of level of BDEs that are present but it is doubtful that it an accurate figure. Obviously with more time a much greater range can be analysed and the level of accuracy would be improved.
  4. The % composition of the various BDE’s present in commercial grade penta, octa and deca BDE vary significantly with time of production and by manufacturer and thus unless each plastic is analysed for all the different BDEs (209) an accurate value of the total BDE is difficult to attain. Obviously the larger the number of BDEs tested for the closer the total value will be to the actual value.

The mass estimation of the plastic components

Unless each product is destroyed so that an exact mass of the plastic that contains the BDE can be measured, one can usually only estimate the approximate mass. If this study were to be extended then the plastic content of each item could be researched by XRF analysis or obtained directly from the manufacturer especially in dealing with the more expensive items.

Estimation of the BDE flows for imports and exports

A large number of categories were identified and the quantities of imports and exports were investigated using New Zealand Statistics data since 1988. However due to time constraints the list is by no means complete. While a significant number of BDE containing products have been investigated for a more accurate determination of the total BDE flows into and out of New Zealand a much more thorough interrogation of the NZ Statistics database is required.

Industrial and Commercial products

The XRF analysis was solely restricted to consumer products focusing on the contents of New Zealand households rather than the commercial and industrial sector. For example, many hospitals, nursing homes, schools, cinemas and commercial offices are believed to have flame retardants in their upholstery and/or curtains yet these have not been analysed. Neither has the transport industry (airports, trains, busses) been analysed nor the fire departments.

Non-bromine containing consumer products may still be ‘unsafe’ as other new POP’s like PFOS may be present. As sampling and collection will be similar these compounds should be included in any future BFR investigation.

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