Occupational and Environmental Toxicology

Occupational and Environmental Toxicology

INTRODUCTION

Description of Departmental Facilities

The Regional Laboratory for Toxicology is situated close to the Pathology Department and the Sheldon Block on the City Hospital site. There is direct access to the Laboratory from the Western Road entrance to the Hospital.

The Laboratory was designated as a Regional Scientific Speciality in 1972, and has been part of the UK Supraregional Assay and Advisory Service (SAS) for trace element analysis since 1974. The Laboratory also has close links with the West Midlands Poisons Unit and Centre for Chemical Incidents (City Hospital), University of Birmingham Institute of Occupational Health and the World Health Organisation (WHO) International Programme of Chemical Safety (IPCS).

All analytical work is performed to the highest standards of laboratory practice, and the Laboratory participates fully in all relevant UK and international external quality assessment schemes. A range of services relevant to occupational and environmental Health are currently available. The principal services available include:

Screening for Drug and Substance Abuse in the workplace.
Biological monitoring of exposure to hazardous substances

Trace Metal Analysis

An advisory and analytical service is provided for several essential and non-essential trace metals. The Laboratory has extensive experience in the investigation of acute and chronic poisoning, following occupational and environmental exposure. Consultation concerning the validity, feasibility and design of research projects e.g. environmental surveys is also available. The Laboratory is a designated Supraregional Laboratory for trace element analysis (SAS).

The elements for which analyses are available, with recommended specimen requirements, are listed below. Please note that great care is required in the selection and use of specimen containers, remembering that there may be batch-to-batch variations in quality – and risk of contamination – in a given manufacturer’s product. Particular care must be taken with lead, cadmium and aluminium.

Laboratory investigations for the assessment of exposure to the following metals is available. For other elements please consult the Laboratory.

ELEMENT	RECOMMENDED SPECIMEN FOR OCCUPATIONAL/ ENVIRONMENTAL MONITORING OF EXPOSURE

Aluminium	Urine
Arsenic	Urine + (blood - acute exposure)
Cadmium	Blood + (urine - excessive exposure)
Chromium	Urine + (blood – speciation study)
Copper	Urine
Lead	Blood + (urine - organo-lead)
Lithium	Urine
Mercury	Urine + (blood - acute exposure)
Selenium	Urine
Thallium	Urine
Zinc	Urine

Complementary Analytes

Erythrocyte zinc protoporphyrin (ZPP) – whole blood

ZPP rises, and returns to baseline more slowly than Lead, it can help differentiate acute from chronic exposure and aid estimates of the period of the latter. N.B. It is also elevated by iron deficiency anaemia.

Other complementary analyses may be available and include:

Haemoglobin and full blood count.
Urine total protein
Urine ß₂-microglobulin
Plasma C-reactive protein
Plasma or red-cell glutathione peroxidase

Pesticides

Measurement of certain pesticides can be carried out directly in blood or urine e.g. paraquat, chlorphenoxyacetates or in the case of organophosphates and carbamate it may be more appropriate to measure red-cell acetylcholinesterase activity. (Please contact the Laboratory for more information).

Organic Chemicals & Solvents

A service is available for the measurement of urinary metabolites of a number of solvents and polycyclic aromatic hydrocarbons (PAH's). The analyses currently available are shown in the Table below. The range of available assays is always being expanded and can be extended to meet a customer's requirement. Please contact the Laboratory to discuss a particular assay or 'exposure' problem. Advice is also available concerning the design of investigations to assess exposure to hazardous substances in the work place and the environment.

Assays Currently Offered for the Biological Monitoring of Exposure to Organic Chemicals

Chemical	Determinant of exposure	Specimen volume (urine)	Recommended sampling time

Xylenes	Methylhippuric acids ¹	20 mL ^2,3	End of shift ⁴
Toluene	Hippuric acid ¹	20 mL^2,5	End of shift ⁴
Perchloroethylene	Hippuric acid ¹	20 mL ^2,5	End of shift ⁴
Benzene	Total phenol ¹	20 mL ^2,5	End of shift ⁴
Phenol	Total phenol ¹	20 mL^2,5	End of shift ⁴
Styrene, Ethyl benzene	Mandelic acid ¹	20 mL ^2,5	End of shift ⁴
Trichloroethylene	Trichloracetic acid ¹	20 mL^2,5	End of shift, at end of working week⁴
Polycyclic aromatic hydrocarbons (PAH) e.g. Coal Tar derivatives	1-hydroxypyrene^1,6 (1-pyrenol)	20 mL^2,3	End of shift, at end of working week.

Notes to Table

¹In order to reduce the effect of varying urine concentration results are expressed as a ratio of analyte : creatinine.

²Specimens should be collected in screw-capped polystyrene containers, and dispatched immediately to the Laboratory by transport or first class post.

³Deep freeze specimens if dispatch to Laboratory is to be delayed.

⁴Workers should be asked to avoid drinking alcohol during the shift on sampling days.

⁵Refrigerate specimens if dispatch to Laboratory is to be delayed.

⁶Contact the Laboratory before submitting specimens for this assay.

Drugs of Abuse Screening

Screening for drugs of abuse is carried out on urine specimens. A wide variety of commonly abused drugs may be detected qualitatively by the "standard" screening procedure (see Table 1).

It should be noted that the analysis of urine will only give information about current or quite recent drug usage. A specimen taken more than a few days after an episode of 'abuse' is likely to be negative on screening for most substances, with the possible exception of cannabis.

The appropriate specimen for screening for drugs of abuse is a 'spot' urine sample (15-20 mL) in a sterile plastic container without preservative. The patient's full name, hospital or other identification number, and the date and time of collection should be written clearly on the specimen container and request form. Special care should be taken to ensure that the specimen obtained is authentic and not subsequently adulterated. Specimens should be sent by courier or first class mail, but if there is likely to be a delay in dispatch, they should be kept in a 4 ⁰C refrigerator prior to being sent to the Laboratory.

Requests for Employment or Pre-employment Screening

A urine drug screening service is available for the purposes of pre-employment or random employment screening. Special request forms and security seals are available to ensure chain of custody, also specialist guidelines. Please contact the Laboratory for further advice.

Confirmation of Results

Confirmation of all ‘positive’ screening tests is generally carried out using gas-chromatography mass spectrometry. The Laboratory also participates in an external quality assessment scheme for drugs of abuse.

Alcohol abuse

Alcohol (ethanol) may be measured in either blood or urine specimens – please contact the Laboratory for more advice, particularly if results are required urgently.

Smoking status

The monitoring of urinary cotinine (main metabolite of nicotine) to determine smoking status of individuals can be performed in blood, urine or saliva. Please contact the Laboratory for further information.

Table 1

Drugs Screened for in the Routine Urine Drug Abuse Screening Request

1. Standard Immunoassay Screen (all specimens)

Amphetamines

Benzodiazepines

Cocaine (metabolite)

Cannabinoids (50 µg cut-off)

Methadone

Opiates

2. Urine Creatinine (all specimens)

3. Additional Substances directly Screened for by Specific Request

Alcohol

Barbiturates

Chlormethiazole

Cyclizine

Diethylpropion

Dipipanone

Ecstasy (MDMA) and related drugs (MDA, MDEA)

Ketamine

LSD

Methadone metabolite (EDDP)

Pethidine

Phentermine

NOTE:

Additional confirmation tests are carried out on all "positive" screening tests at no extra charge.

Last modified: April 13, 2005