Note On Liver And Blood In Relation To Occupational Hazards

These disorders are uncommon.

BLOOD:

1. Conditions to be particularly aware of are aplastic anaemia or leukaemia due to benzene. You are unlikely to find benzene being used as a solvent in industry today. (Do not confuse with benzine). If it is, it should be substituted with a less toxic solvent. However, you may find someone with past exposure to benzene as well as current exposure to a raw material in the petroleum or chemical industry.

In any case of aplastic anaemia or the appropriate type of leukaemia, a careful employment and exposure history should be taken.

The question arises whether benzene derivatives such as xylene and toluene are capable of causing the same effects as benzene. There may be some risk in certain uses owing to contamination of industrial grades of these solvents with small amounts of benzene. There are also epidemiological studies linking "solvent exposure" with aplastic anaemia. However, the evidence for xylene or toluene as causes of leukaemia seems to be weak.

2. Methaemoglobinaemia is an interesting condition from a pathophysiological point of view. (Non-medics should not worry about the biochemistry). The condition and its treatment also bring into consideration inherited enzyme defects, specifically G6PD deficiency.

For the clinical approach to methaemoglobinaemia, refer Le Dou (3rd edn.) ch. 15, pp 214-215. Diagnosis is based on recognition of the cyanosis (blue lips, etc.) in an employee and referring him/her for investigation. A high index of suspicion, related to a knowledge of the work exposures, is required to make this diagnosis, which is presumably rare.

Note the useful discussion in the reading by Goldstein on the problems of screening for enzyme defects among employees.

3. Arsine as a cause of haemolytic anaemia and lead as a cause of anemia have been covered under metals.

LIVER:

Probably the most common presentation is an employee with elevated liver enzymes who is also exposed to solvents. You should have some understanding of the differential diagnosis of raised liver enzymes, particular alcoholic liver disease, infection and common conditions such as idiopathic steatosis.

Viral hepatitis may also be an occupational disease, specifically in health care workers and others exposed to blood products or unsanitary conditions.

An understanding of the different effects that various chemical agents (or classes of such agents) have on the liver is needed in designing a medical surveillance system for liver hazards. You should have a procedure for interpreting abnormalities and a referral protocol for assistance with persistently abnormal results. Distinction from other common causes will always present a problem.

Temporary removal from exposure of workers with abnormal liver tests due to work exposures should result in the test results returning to normal.