CCC Bin Site in Iowa - 1956 Photo: Bob Lichtwardt
Billions of tons of surplus cereals including corn were stored in the midwest in the fifties. They were contained in 'Butler' bins with a capacity of about 3000 bushels per bin. Each storage site had large numbers of bins lined up in rows covering acres of land. They looked like fields of giant beer cans (you wish!). If corn is not stored at just the right moisture content then there is considerable moulding inside the bins. Why this happens is biologically very interesting and afficionados on fungi should click here for an explantion.
Dr. Robert (Bob) Lichtwardt and I were working on the Corn Storage Research Project centred at Iowa State University, Ames. Bob was the senior man on the project and I was a graduate student earning bread and butter money (more like bread and margarine actually) on this project while I worked on my Ph.D. It was our responsibility to study the deterioration of corn in storage and make recommendations for control.
To do this we had to climb to the top of randomly selected bins, pop the lid, and jump into the bin. We then had to assess the corn visually and by taking samples. We sampled to a three foot depth in each bin and analysed the samples both quantitatively and qualitatively for fungi. It was a big job for such a small team. We processed hundreds of samples. Each corn sample had to be ground for thirty minutes in a special grinder (corn is tough stuff ). We then made a dilution series of the ground suspension in very weak agar and plated out each of the final three dilutions in triplicate. We also plated out whole kernels on selected media. I spent my waking hours cleaning and sterilizing plates, making up media, making counts, identifying fungi etc etc. my life was a blur.
But enough of this boring mycobiography. Cut to the chase! Bob and I went into many bins, many times, and took samples by the hundreds. Sometimes the bins were fairly clean often they had heavy mould growth. Tramping around inside the bins and taking samples often caused significant disturbance of the mouldy corn resulting in massive numbers of airborne spores. Sometimes the air was cloudy with spores of Aspergillus, Penicillium and who knows what else (actually I have a full list of these). In accomplishing our appointed tasks, we inhaled fungus spores by the millions!
In retrospect, I do think we tempted fate. I also think that we should have shown the fungi a little more respect. Although, in fairness, I should emphasize that the whole field of mycotoxins was unknown at that time (turkey X and aflatoxin surfaced about 1960) and discovery of toxins in airborne mould spores was much later than that.
Now this is hardly a definitive experiment. It is closer to what is generally referred to as anecdotal evidence. Nevertheless, it is very clear from this experience that normal, healthy individuals can be exposed to extremely high concentrations of airborne fungal spores repeatedly with no obvious long term effects on their health.
Interestingly, because of the perceived hazards, we would no longer be allowed to do this without specialized clothing and breathing apparatus and goodness knows what else.