Unreliable alcohol testing in a shipping safety programme.
BACKGROUND
Within a maritime alcohol and drug testing programme, a case showing an unphysiological urine ethanol concentration (235 mmol/L, 10.8 g/L) was found. The sample contained low levels of the ethanol metabolites ethyl glucuronide (EtG) and ethyl sulphate (EtS) which confirmed prior drinking, but also tested positive for the fermenting yeast Candida albicans which suggested post-sampling ethanol formation. This and other questionable cases prompted investigation of the suitability of urine alcohol testing for the intended application.


METHODS
Besides the routine measurements of ethanol, illicit drugs and creatinine, randomly selected ethanol-positive and ethanol-negative urines collected within the maritime programme were checked for the presence of EtG and EtS and for fungal and bacterial growth. Data on sample handling and storage was also gathered.


RESULTS
Ten of 15 (67%) ethanol-positive and 4 of 9 (44%) ethanol-negative urines contained yeast and/or bacteria. Among the ethanol-positive cases, 4 (27%) were obviously false positives because EtG and EtS were not detected. Microbial action as the reason for false-high ethanol concentrations was indicated in other cases. When 17 bacteria-infected but fungi-negative urines were supplemented with glucose and stored for 1 week at 21 degrees C, ethanol was formed in 2 specimens containing Escherichia coli and E. coli plus P. aeruginosa. In these samples, EtG was also formed on storage while EtS was not.


CONCLUSIONS
The routines employed for urine collection and handling within this substance abuse programme caused many false-positive identifications of alcohol use with unintended medico-legal consequences. Unpreserved urines stored without cooling should not be used for alcohol testing, given the high risk for microbial interference.
Helander
Anders
A
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. anders.helander@ki.se
Hagelberg
Charlotte Asker
CA
Beck
Olof
O
Petrini
Björn
B
D000062:Accidents, Occupational / Q000517:prevention & control; D000428:Alcohol Drinking / Q000652:urine; D002176:Candida albicans / Q000302:isolation & purification*; D002492:Central Nervous System Depressants / Q000652:urine*; D004926:Escherichia coli / Q000302:isolation & purification; D000431:Ethanol / Q000652:urine*; D005189:False Positive Reactions; D005965:Glucuronates / Q000652:urine; D006801:Humans; D008297:Male; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D012767:Ships; D015813:Substance Abuse Detection; D013463:Sulfuric Acid Esters / Q000652:urine; D014556:Urine / Q000382:microbiology*
D002492:Central Nervous System Depressants; D005965:Glucuronates; D013463:Sulfuric Acid Esters; C093924:ethyl glucuronide; D000431:Ethanol; C011612:diethyl sulfate