Arsenic is mainly measured to assess occupational exposure: eg. workers manufacturing semiconductors in the microelectronics industry (who are potentially exposed to arsine gas), agricultural workers using arsenical herbicides and pesticides, and workers exposed to wood preservatives containing copper, chromium, and arsenic.4
Exposure can be monitored by measuring urinary excretion of arsenic, which is present as arsenite (As3+) and arsenate (As5+) which are both highly toxic. When methylated to methylarsonic acid and dimethylarsinic acid their toxicity is substantially decreased. Arsenobetaine is a common species which is non-toxic and is present in the normal diet from fish and crustaceans. Another category of arsenic species, arsenosugars, which are present in some shellfish (e.g. oysters, mussels, clams) and in seaweed extract, break down in the body to give monomethylarsonic acid and dimethylarsinic acid. Therefore, on finding a high urine arsenic concentration it is not possible to distinguish between occupational exposure and a diet containing substantial amounts of shellfish. Limiting dietary intake of shellfish for about five days before urine measurement can be used to investigate raised urine arsenic concentrations. Alternatively speciation of the arsenic can be done.
Hair arsenic provides a more integrated measure of arsenic exposure, although this is also subject to external accumulation of arsenic from the environment.5
In some parts of the world (Bangladesh, Thailand, China) arsenic is found in levels up to 500 μg/L (WHO recommended limit = 0.05 μg/L) in drinking water taken from deep-bore wells. This has resulted in a large increase in cancer rates (especially skin cancer) and peripheral vascular disease causing gangrene.
Some non-Western traditional medicines may contain large quantities of arsenic and can be accessed over the internet, mainly from India.
Acute arsenic poisoning may result in abdominal pain, weakness and trembling. Longer-term poisoning may cause skin complaints and skin and liver cancer.6,7
Sample Requirements and Reference Ranges for Arsenic
|Sample Type||Hair, urine (random)|
Urine: universal container
Hair: sealable plastic bag*
Urine: 1 mL**
Hair: A bundle of hair about the length and half the thickness of a cocktail stick.
Urine arsenic: < 30 nmol/mmol creatinine (STEMDRL derived)
Hair arsenic: < 0.15 µg/g 8
|Mean Turnaround time||Urine: 5.5 days|
|Method||Inductively coupled plasma mass spectrometry|
Urine: Traceable to reference material produced in accordance with EN ISO 17511:2003 “In vitro diagnostic medical devices. Measurement of quantities in biological samples. Metrological traceability of values assigned to calibrators and control materials” and reference materials with values determined by reference laboratories.
Hair: Traceable to certified reference material ERM DB001.
|Intermediate Precision (CV)||
Urine: 7.1% at 506 nmol/L, 3.8% at 2157 nmol/L.
Hair: 5.0% at 0.69 µg/g, 9.0% at 1.20 µg/g
|Measurement Uncertainty, U||
Urine: 543 ± 28 nmol/L, 3483 ± 183 nmol/L
Hair: 0.2 ± 0.03 µg/g, 1.0 ± 0.31 µg/g
|Analytical Goals (CV)||Urine: 6%***, Hair: 10%***|
Urine: UK NEQAS, Guildford (once per month)
Hair: Quebec Multi-Element Quality Assessment Scheme (3 times per year)
* A lock of hair, cut close to the scalp and about the thickness of a cocktail stick is required. Hair should be collected into a sealable plastic bag ideally with the lock tied to maintain its integrity. It is easiest to tie the lock at the root end before it is cut. To assess recent exposure, a section of hair close to the cut end is analysed. If the suspected date of exposure is in the past please indicate on the request form the approximate date; we will then analyse the appropriate section of hair based on the mean growth rate of hair of around 10.6 mm/month.
** Absolute minimum volume; this volume is insufficient to carry out repeat analysis if analysis fails.
***Goal Origin: STEMDRL state-of-the-art