Monday, July 13, 2009

Pregnancy and Fitness for Work

Author: Dr John Low (Occupational Physician: OccuMED)

In normal pregnancy, during the first trimester (first 12 weeks following conception), nausea and sometimes vomiting commonly occurs leading to deterioration in work performance. Fatigue is also a common problem not only in the first 12 weeks but also during the latter stages of pregnancy. This may be exacerbated by shift work and long hours at work.

In the second trimester (13 - 26 weeks), many pregnant women experience musculoskeletal problems because of the physical changes in their body including weight gain, increased girth and changes in their postures as a result. Towards the end of the second trimester, more physical difficulties may be experienced such as reduction in affective arm reach, balance becomes less stable and falls are more common due to the body's change of centre of gravity. Dizziness and fainting may also occur particularly in hot environment or with prolonged standing.

In the third trimester (after 29 weeks), the problems of the second trimester continue but fatigue becomes more pronounced and is often worsened by insomnia. There may be a variety of aches and pains, constipation, haemorrhoids, varicose veins, bladder problems which all may affect a women's work capacity.

Labels: Fitness for Work

Saturday, July 11, 2009

Hearing Loss and Fitness for Work

Authors: Dr John Low / Dr Roger Lai (Occupational Physician: OccuMED)

People with hearing loss may have difficulty listening to normal conversations, hearing in the presence of background noise, using communication systems, hearing warning signals and localising the direction of a sound source. It may also affect their ability to use hearing protection.

Significant hearing loss can affect fitness for work in jobs that require good communication or where catastrophic consequences may result (ie. serious injury due to failure to hear a warning signal). Exposure to excessive noise may further compromise hearing ability.

In certain occupations where there are specific hearing requirements, governing organisations often develop medical standards. For example, the National Road Transport Commission has hearing guidelines for commercial drivers.

Where there is no such medical standard, a person with significant hearing loss needs to be assessed on their ability to undertake the inherent requirements of the job safely and effectively with or without modifications which do not cause undue hardship on the employer (e.g. installation of visual warning systems). Otherwise, denying the person a job based on hearing loss may be deemed discriminatory.

In these cases the extent of the hearing loss should be assessed clinically and/or audiometrically but the disabling affects of hearing loss should be assessed practically in the work scenario. The disabling effects of hearing loss are dependent on multiple factors including type of hearing loss, the distance from the sound source, background noise, job experience etc. Job experience and skill may outweigh any potential disadvantage suggested by pure tone audiometry done in a controlled environment which may be unrelated to the real work setting

Labels: Fitness for Work

Tuesday, March 24, 2009

Urine Drug and Alcohol Screens

Author: William McConnell (Scientist in Charge Biochemistry: Clinipath)

What drugs do we look for?

The main drugs looked for in a standard urine drug and alcohol screen are:

Alcohol

Amphetamines (includes dexamphetamine, methamphetamine and ecstasy

Benzodiazepines

Cannabis (THC

Cocaine

Methadone

Opiates, including 6-monoacteyl morphine (6-MAM

What are the cut-off levels for a positive result?

The following cut-off levels are used for reporting drugs of abuse in urine.

Alcohol 0.02% (zero tolerance cut-off); 0.05% (common cut-off)

Amphetamines (300 ug/L)*

Benzodiazepines (200 ug/L) *

Cannabis (50 ug/L) *

Cocaine (300 ug/L as metabolite) *

Opiates (300 ug/L) *

6-MAM (10 ug/L) *

Methadone (100 ug/L as metabolite EDDP)

* cut off level taken from the AS/NZ 4308:2008 standard.

How long do these drugs stay in the system?

Some drugs are cleared rapidly from the system while others can persist for a long time. Regular use of a drug can also mean it stays in the system longer.

As a guideline most common drugs have the following clearance rates.

Alcohol 12 hours

Amphetamines 2-4 days

Benzodiazepines 3-10 days (up to a month if heavy use

Cannabis up to 6 weeks

Cocaine 2-4 days

Methadone 3-5 days

Opiates 2-4 days

Will passive smoking lead to a positive result for Cannabis?
The cut off level for Cannabis has been chosen to exclude passive smoking as a cause for a positive result.

A donor will not test positive for Cannabis as a result of passive smoking unless the exposure has been extreme. The donor will be aware of such exposure.

What does it mean if the urine is dilute?

A chemical called creatinine is present in urine and this is measured to see if the sample is dilute. If the donor drinks too much water, the urine may become very dilute.

A dilute sample will still be tested and positive results will be reported. Negative results will be marked as unsuitable and a repeat sample will be requested.

If a donor continues to present dilute samples with no reasonable medical explanation then intentional dilution to avoid detection must be considered.

What does it mean if the temperature check fails?

A freshly produced urine sample should be at body temperature.

If the temperature is outside expected values then sample substitution or tampering must be considered. The temperature check may also fail if an insufficient volume of sample is produced.

If the temperature check fails it will be noted on the report and a repeat collection will be recommended.

Is the sample checked for masking agents?

All urine samples are checked in the laboratory for compounds commonly used to interfere with drug testing. If interfering compounds are detected this will be indicated on the report.

What is the difference between a screen and a confirmation?

The initial screen for drugs uses an immunoassay that looks for selected drug classes. Positive screening results can be caused by prescription and over the counter medications and so it is important to note any recent medications on the chain of custody form before the testing is done.

Confirmatory testing is done using a technique called Gas Chromatography with Mass Spectrometry (GC-MS). This is a highly accurate technique that is able to specifically identify and quantitate individual drugs that may be present.

Labels: Urine Drug and Alcohol

Monday, March 23, 2009

GC/MS Confirmatory Testing

Screening and Confirmatory Testing
Author: William McConnell (Scientist in Charge of Biochemistry: Clinipath Pathology)

All urines are first checked by a screening test using immunoassay. This is an analytical process that uses specific antibodies to detect compounds of interest. When screening for drugs of abuse we have specific cut-off levels defined by the Australian standard AS: 4308.

The AS: 4308 standard also requires confirmatory testing to be done on samples where the screening test detects a compound above the specific cut-off value.

Confirmatory testing by Gas Chromatography with Mass Spectrometry (GC/MS) or an approved equivalent should be done on all samples where a compound is detected by the screening test. The GC/MS allows us to look for specific compounds and can determine if certain drugs are present and if this is consistent with any stated medication. This also allows us to distinguish between legally available compounds and illicit drugs.

Confirmatory Testing

Opiates
Codeine and Morphine are the main Opiates looked for during confirmatory testing. In addition 6-Monoacetyl Morphine (Heroin metabolite) can be looked for if the screening test indicates this compound may be present. Codeine breaks down to Morphine in the body and the presence of both in the urine is consistent with the use of a medication containing Codeine.

Heroin breaks down to 6-Monoacetyl Morphine and then to Morphine. If 6-Monoacetyl Morphine is detected by confirmatory testing above the cut-off level of 10 ug/L this result is consistent with recent Heroin use. Very high levels of Morphine are usually seen with the use of Morphine or Heroin. Prescription access to Morphine is very restricted and claims of its legal use may require verification.

Poppy seed ingestion can also lead to detectable levels of Morphine in the urine. If poppy seeds have been ingested, Morphine is usually less than 2000 ug/L however Morphine has been reported as high as 11571 ug/L after poppy seed consumption.

The cut-off level for confirmatory testing for Codeine and Morphine in urine samples is 300 ug/L.

Amphetamines
The Amphetamine type substances are a large family of compounds that include both lawfully available and illicit drugs. Ephedrine and Pseudoephedrine are found in “Cold and Flu” medication and can be obtained over the counter from a pharmacist. The cut-off level for the detection of Ephedrine and Pseudoephedrine is 500 ug/L.

Phentermine and Amphetamine (also called Dexamphetamine) are available on prescription. The confirmatory cut-off levels are 500 ug/L and 150 ug/L respectively. Both can also be drugs of abuse and claims of legal use should be verified.

Methamphetamine (ICE, Crystal Meth), MDMA (Ecstasy) and MDA are not present in medications and their use is unlawful in Australia. The confirmatory level for these compounds is 150 ug/L.

Cannabis
The Cannabis cut-off for GC-MS is 15 ug/L which is much lower than the cut-off for the immunoassay screening test. This is because the screening test looks for a family of chemicals produced as a result of Cannabis use. The GC-MS specifically looks for the 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (Carboxy-THC) which is the main by-product of cannabis use found in the urine. Carboxy-THC above the cut-off level of 15 ug/L is consistent with Cannabis use.

Cocaine
The GC-MS for Cocaine looks for two main breakdown products of cocaine metabolism which are Benzoylecgonine and Ecgonine methyl ester. The presence of either of these compounds above the cut-off level of 150 ug/L is consistent with recent Cocaine use.

Benzodiazepines
Benzodiazepines are a common prescription medication. GC-MS or LC-MS confirmatory testing can determine if compounds detected in a urine sample are consistent with Benzodiazepine use. In addition the results can be compared to the stated medication to indicate if results are consistent. Different Benzodiazepine medications will result in different breakdown products being detected in the urine sample. The cut-off level for urine Benzodiazepines in confirmatory testing depends on the compound and may be 100 ug/L or 200 ug/L

Labels: Urine Drug and Alcohol

Thursday, May 22, 2008

Return to Work Resource

1) Return to Work Knowledge Base:

http://rtwknowledge.org/

Wednesday, January 23, 2008

Nickel Dermatitis

Nickel dermatitis is a common type of allergic contact dermatitis. It is the most common allergen found with allergy patch testing. Nickel allergy is more common in women. It can occur at any age, and once it develops, it persists for many years. The most common source of nickel allergy is after ear piercing and contact with nickel containing ear rings.

The degree of nickel allergy and the development of dermatitis varies. It may occur after a brief contact with a nickel product, or it can occur after many years exposure to a nickel containing material.

The dermatitis develops either in the area where the product comes in contact with the skin, or sometimes people develop blistering dermatitis on their hands and feet known as pompholyx.

Nickel allergy is diagnosed by the clinical history and by allergy patch testing.

The treatment for nickel dermatitis involves the use of potent topical steroids to the area of dermatitis. This may be used under wet compresses to aid in penetration, and to dry up the weepy skin. If the nickel dermatitis is severe or widespread, systemic steroids may be needed.

It is essential to avoid nickel containing metals once nickel allergy has been confirmed on history and with patch testing. To test if metal items contain nickel, a nickel testing kit containing solutions of dimethyglyoxime and aluminium hydroxide are mixed together, and in the presence of nickel, it turns a pink colour. Unfortunately desensitization to nickel with injections or pills is not possible. Nickel allergy is difficult to prevent once it occurs as nickel products are found so commonly in everyday use.

Dr. Ernest Tan
MBBS FACD
Consultant Dermatologist
Burswood Dermatology
87 Burswood Road
Victoria Park WA 6100
Australia

Tel: 618 9470 3064
Fax: 618 9470 4479

Labels: Dermatitis