[3] Six varieties of this species have been recognized based primarily on differences in colony colour: P. verrucosum var.

[4] Its growth is carefully regulated in order to reduce food spoilage by this fungi and its toxic products.

[5] Later, after disagreements arose upon the identification and naming of these fungi, their growth rates, mycotoxin productions and sources were observed.

[7] It is widely distributed in food (such as cereal[4]) and animal feed where grains (usually barley, wheat and rye[4]) are a key ingredient.

[14] Pigs raised in northern and central Europe develop nephritis after consumption of contaminated feed.

[8] Penicillium verrucosum is a contaminant of cereal crops (such as barley, maize, oats and wheat) which are used in animal feed.

[10] Spoilage of the grain by OTA occurs as a cause of inappropriate storage temperatures and moisture content.

[15] To prevent OTA formation, grains must be dried to moisture levels lower than the 18% limit shortly after harvest.

[17] Protozoa, bacteria, yeast, filamentous fungi and plant cell cultures are all used in these biological procedures.

[17] During the 1950s, reports of kidney disease with high rates of mortality were occurring in geographically close areas, such as Bulgaria, Yugoslavia and Romania.

[14] This occurrence was called the Balkan Endemic Nephropathy[14] that was being caused by the consumption of contaminated pig meat in those areas.

[7] When pigs consumed feed contaminated by OTA, it collected in their fatty tissue rather than being excreted due to its solubility in fat.