APROPOS the news reports in the media regarding the mystery of 14 people dying of gas inhalation in Karachi. The reports appearing in Dawn — ‘Mystery gas leak death toll doubles amid blame game;’ ‘Hydrogen sulphide, nitric oxide found in Keamari during monitoring of air quality’ (Feb 19) and ‘Keamari gas leak remains a mystery’ (Feb 20) — were factual and balanced.

However, many other media reports along with some of the institutional comments and government advisory have created confusion with regard to soybean allergy!

The allergic reaction to any aeroallergen takes place in humans with a previous history of sensitisation or in genetically predisposed individuals having a “specific IgE antibodies” to that particular aeroallergen.

Soybean dust, soya or soybean has its origin in food and therefore any dust emanating from a ship loaded with soybean may normally affect only previously sensitised individuals.

Analysis of blood samples for only Immunoglobulin E (IgE) is no proof of their sensitization; it has to be the IgE specific antibodies to soybean.

Once sensitised, one can have respiratory allergic reactions with manifestations of asthma, wheezing sneezing and so on.

It is highly unlikely that a large number of Keamari residents would have pre-sensitisation to soybean. Once ingested, in such patients, it can cause abdominal reactions resulting in skin rashes and hives etc.

Second, the dust may contain soybean fragments or its pollen fragments or even contaminated by various known allergenic fungi such as aspergillus, penicillium and/or alternaria species. Such scenarios, either ingested or inhaled, may lead to a temporary bronchoconstriction and inflammation in respiratory bronchioles (non- allergic) even in a patient not genetically predisposed or sensitised. Nevertheless, this is not going to kill so many patients and cause hospitalisation of the nearby population.

Third, soybean allergy is the least incriminated in any anaphylactic shock (generalised whole body reaction and death).

Anaphylactic shock, well-known with peanuts and shrimps food allergy, can kill a patient but anaphylactic reaction with soybean dust on such a large scale is not conceivable. The air quality sampling must have been conducted for both, aeroallergens and gases before issuing a dust allergy advisory.

It appears that there must have been some toxic gases release, for a short while, and this must have been inhaled by the individuals present in that area. This prospect needs full investigation.

Prof Dr Syed M. Hasnain
Riyadh, Saudi Arabia

Published in Dawn, February 23rd, 2020