The main exposure to arsenic in New Zealand occurs in the timber treatment industry. The preservation of timber (tanalising) is carried out using a mixture of salts of copper sulphate, potassium dichromate and arsenic pentoxide. The timber is pressure injected with the preservation liquid in large pressure cylinders, after which it is stacked in the yard while still wet with preservation chemicals. Arsenic may also be encountered in the plating industry and in foundries and glassworks, and is found in some fruit tree sprays. To ensure accurate assessment of exposure to arsenic, urine samples must be collected at the end of the working shift at the end of the working week if the exposure is continuous, as the half-life of arsenic in the urine is approx. 48 hours. The method used does not measure the organic arsenic compounds present in dietary fish, samples can be collected without dietary restrictions.
Send to separating if ambient on arrival. Send to lipids/trace metals if frozen on arrival.
Make aliquot for UCRN. Send primary sample to lipids/ trace metals.
If urine results are elevated (above the Biological Exposure Index), and it is unclear what the source of the potential exposure is, then the laboratory suggests the following protocol is followed:
Do a follow-up test at the end of a further working week, then re-test on the following Monday (after 48 hours of non-exposure coupled with avoidance of shellfish). The expectation is that the concentration would halve and may fall under the recommended limit.
Shellfish avoidance should then continue. Further testing at the end of the next working week should give a gauge of the effect of working practices and the requirement for any adjustments.
Note: The half-life of arsenic is in the order of 48 hours.
Methyl compounds (eg DMA from shellfish) can contribute to reported inorganic arsenic levels.Collect at end of shift at end of the working week for industrial exposure.
Ambient (8 - 24 degrees Celsius)
The urine pottle used for specimen collection must be shown to be free of Arsenic contamination. Industrial samples collected at the end of working week. Inorganic arsenic levels are not affected by organic arsenic of dietary origin (i.e. fish). Urine Chromium can be done on the same sample.
Normal non exposed level <0.47 umol/L
0 – 0.02 umoL/mmoL creatinine
Biological Exposure Index for inorganic arsenic and its methylated metabolites is 0.47 umol/L (35ug/L)
Workplace Exposure Standards 2018
Column exchange chromatography, ICP-MS analysis of the inorganic fraction.
$57.30 (Exclusive of GST)