Allergies (ILO/IMO Guidelines Appendix E T78, Z88)

Introduction

A wide range of health problems may be attributed to an allergy. The quality of evidence supporting the diagnosis varies widely and, because of the implication that a severe reaction may occur in the event of further exposure to the allergen, such a diagnosis may restrict a person's life and employment opportunities.

Allergic asthma and dermatitis are among the most common forms of allergy but in both cases irritant mechanisms can also either be a sufficient cause for similar symptoms or contribute to the response in those who do have an allergic reaction. A considerable range of foods can cause adverse effects and here the separation of true allergy from the effects of habit, dislike and infection can be difficult. Other environmental agents causing allergy include plants, animals and chemical agents.

Patterns of allergic response are often established in childhood. Some such as asthma and eczema often resolve with maturity. However an allergic response can develop at any age and occupational causes, including some agents that are found at sea, can cause the onset of an allergy in a working age person.

Impairment and risk

• The importance of allergy in relation to fitness to work at sea lies in the possibility of a repeat exposure to an agent to which a person is allergic leading to a severe or life-threatening response in a situation where the medical support needed to treat it is not available.
• Likely forms are exacerbations of asthma and generalised reactions to foods such as nuts.
• Allergic dermatitis will not present such an immediate risk but can prevent seafarers from doing their duties, especially where these involve contact with foods, liquids, solvents and detergents.

Rationale and justification

• There is no evidence about risks in seafarers beyond case reports of incidents of allergy. Hence information from onshore studies needs to be used.
• Test methods can be used to detect some forms of allergy, for instance skin prick tests for dermatitis or specific immunoglobulin levels for some agents causing asthma and anaphylaxis. There are in addition many more doubtful tests promoted by commercial interests and alternative practitioners.
• An expert clinical opinion is often essential to determine whether signs and symptoms have an allergic origin and so can be expected to recur and become more severe with even minute exposures to the causative agent. This opinion will rely on the history of the condition, the clinical findings during and between episodes, the response to therapy as well as on test results.
• Immediate treatment with adrenaline and steroids can abort an acute episode. In the longer-term steroids, bronchodilators (asthma), antihistamines (general responses) and topical treatments (dermatitis) may suppress effects but will not cure the underlying sensitivity.

Assessment and decision taking

Seafarers have presented to Approved Doctors with a wide range of proven or suspected allergies. Apart from allergic dermatitis and asthma there is no mention of allergies elsewhere in the published medical standards. Hence decisions have had to be taken from first principles. The variability and changing severity of allergic responses means that it is impossible to write a single standard which has meaning and general validity. Some of the principles applied in the case of asthma and dermatitis are sound starting points for other allergic responses, and it may be helpful to ask the following questions:

• Is the diagnosis of an allergic mechanism secure? Could irritation or infection, for instance, be the cause? This is important because the features of increasingly severe reactions and the need to avoid exposure totally to prevent recurrence are specific to allergy and are major reasons for deciding that a person is unfit. Confirmation by a suitably qualified medical specialist should be obtained if there is any doubt, as many people self diagnose or receive advice from less orthodox practitioners, leading to unsubstantiated labelling of conditions as allergic.
• Is the causal agent known? This is important because it may determine whether it is likely to be present at sea. Thus an exposure to cats or to bee stings will usually be avoided at sea (if not in port), but eating peanuts, which are likely to be a trace ingredient in many foods, will be hard to avoid.
• What is the nature of the allergic response? If it is a skin rash or intestinal disturbance this would be impairing but not life threatening, whereas anaphylactic shock can be rapidly fatal.
• What is the pattern of past responses? How frequent have they been and is there a pattern to their severity such that each is more major than the one before? Has the same amount of allergen exposure been needed on each occasion or has it been less each time? Both these facets may be important predictors of the risk from future exposures.
• Is prevention based on avoidance or is any medication used? If medication is required then some degree of surveillance may be needed.
• Does the sufferer self treat in the event of an episode? 'Epi Pens' are commonly used but their adequacy in the absence of rapid medical support will usually mean that they are not acceptable as the mainstay of management at sea.

Note: If an occupational cause for an allergy that is present in the person's current pattern of employment is found it is important that the ship operator is made aware of this, this may be directly with the consent of the individual or by informing the MCA of the details of the case and providing contact information on the operator.