408 Articles of general interest--Fd Cosrner. Tosicol. Vol. 17. No. 4

citrinin and OTA produced ulceration of the intes- Swedish porcine nephropathy, in which OTA appears tinal mucosa. It could not be established, however. to be a major aetiological factor, have been particu- whether the enhanced toxicity when both mycotoxins larly associated with very specific geographical areas. were given together was synergistic or merely addi- Fungi capable of producing OTA under appropriate tive. conditions are more widespread, however, and the

In a third paper (idem, ibid 1977, 14, 392), the ultra- arrival in Bournemouth of a consignment of flour structural changes in the kidneys of dogs given OTA contaminated with OTA was reported recently. or citrinin were compared. No changes were seen in Richardson er a/. (Lancer 1978, II, 1366) found that the epithelial cells of the proximal or distal tubules some caked and discoloured culinary flour from two of dogs given 5mg citrinin/kg, but in those given sacks that were the subject of a complaint contained IOmg/kg the cells of the proximal tubules showed 6.25 mg OTA/kg, as determined by thin-layer cytoplasmic vacuolation, myelin-figure formation and chromatography. It appeared that the flour had cytoplasmic disarray mainly affecting the endo- become damp during storage and this had caused membranous system. and cytoplasmic vacuolation proliferation of P. cyclopium and the consequent pro- together with some cytoplasmic disarray and mitotic duction of OTA. The OTA level quoted was limited figures was apparent in the cells of the distal tubules. to the obviously affected part of the flour, and it was In this group, some secondary mitochondrial swelling estimated that the overall concentration in the sacks was seen in severely affected cells. The changes in was below 1 mg/kg. This appears to be the first in- the proximal epithelial cells after 0.1 or 0.2 mg stance in which a high level of OTA has been detected OTA/kg were similar, but the cells of the distal tubu- in retail foodstuffs in the UK. The actual health risk lar epithelium were not affected in these animals. in this case was apparently not serious and it should Thus, the location of lesions within the nephron not be exaggerated. However, the incident does un- occurred primarily in the proximal tubules with OTA derline the need to maintain a careful watch for the alone, and in the distal tubules with citrinin alone. possible occurrence of mycotoxins in foods and, as When combined doses of both mycotoxins were the authors of this report suggest, indicates the advis- given, lesions occurred in both parts of the tubule ability of reconsidering the current practice of divert- and the collecting ducts. but the citrinin-induced ing into animal feeds milled flour that has become lesions predominated. discoloured by mould contamination.

Balkan nephropathy, with its possible association with human diets contaminated with OTA, and [P. Cooper-BIBRA]

AFLATOXINS AND THE LIVER

Fungi that synthesize aflatoxins. particularly Asper- gillus Javus and A. parasiticus. are common natural contaminants of peanuts, cotton seed, soya beans, pecans, cereals. pulses, cassava and sweet potatoes. Among the different aflatoxins identified, aflatoxins B, and G, have produced liver cancer when fed to rats, while B, has produced liver tumours only when injected ip (Cited irl F.C.7: 1976, 14, I5 I). These myco- toxins have been shown to affect a wide range of ani- mal species, and the susceptibility of primates has been demonstrated in several laboratory tests.

Following some early very small studies in which the feeding of mixed aflatoxins to rhesus monkeys was associated with the developement of hepatocellu- tar or bile-duct carcinoma (Gopalan et al. Fd Cosmef. To.uico/. 1972, IO, 5 19; Tilak, ihid 1975, 13, 247). Adamson er ul. (J. tlurn. Cancer Inst. 1976, 57, 67) have reported that three of 42 rhesus monkeys devel- oped primary liver cancers after receiving total doses of aflatoxin B, ranging from 99-842 mg over periods of 48-74 months, although no such cancers developed in 20 control animals and none had been detected in 250 untreated monkeys kept in the colony during the previous I5 years. An indication of the possible hazard of working with aflatoxin has come from Deger (AWL intern. Med. 1976, 85, 204), who reported that two men, aged 42 and 28 years, developed col- onic carcinoma after spending 3 years and I year, respectively. scraping aflatoxin from chromatographic plates. Despite the impossibility of establishing a

cause-and-effect relationship in these circumstances. the known carcinogenic potential of aflatoxins and the rarity of colonic adenocarcinoma in relatively young men combine to raise grave suspicion.

Investigations of the carcinogenic potency of afla- toxin in man, however, have been concerned mainly with the possible association between liver tumours and aflatoxin-contaminated diets. EpidemIological studies involving diet and tissue analyses have been conducted over the past decade in areas in which the incidence of primary liver cancer is particularly high. Some of the earliest work was carried out in Thailand and this was followed by several studies on various African populations (Cired itI F.C.T 1976, 14, 152).

Following earlier work in Kenya, Peers er al. (Inr. J. Cancer 1976, 17, 167) studied exposure to aflatoxin among a Swaziland population whose main articles of diet were maize porridge, groundnuts, sour drinks and beers. supplemented with jugo beans, sorghum and various pulses. Samples of food were collected every 2 months for I year from the different areas selected to provide a range of climatic and socio- economic conditions and of food storage and handling methods. Analysis of these samples for aflatoxin and calculation of daily aflatoxin ingestion levels estab- lished a significant correlation between individual daily intakes of the mycotoxin and the incidence of primary liver cancer in adult men in different parts of Swaziland. Although the aflatoxin contamination of food is related mainly to poor storage, no seasonal

Articles of general interest-fd Cosmer. Tolticol. Vol. 17. No. 4 409

effect on the atlatoxin content of samples could be appeared in a concentration of 4Ong/g. Stora (C.r.’ demonstrated, suggesting that the discriminatory sort- hebd. SPanc. Acad. Sci., Paris 1978. 286, 917) has de- ing of maize and groundnuts and the consequent dis- scribed a technique used for detecting aflatoxin in sec- carding of mouldy stocks reduces exposure to afla- tions of tissue from primary liver tumours obtained toxin throughout the year to a fairly constant pattern. from a population studied in Zaire. The method, This report adds some detail to the pattern of the based on fluorescence microscopy, differentiates relationship of liver cancer to dietary aflatoxin intake between the fluorescence of aflatoxins B,, B, and already reported for other areas of Africa (Cited in their metabolites, and between that of aflatoxins G,. F.C.T. 1976. 14, 152). G2 and their metabolites.

Susceptibility to the acute toxicity and/or carcino- genic potential of aflatoxin varies widely between species and even among strains of the same species, and the relationship between these two aspects of aflatoxin activity remains far from clear (ibid 1978, 16. 403). The signs of acute aflatoxicosis reported in the baboon, notably a varying degree of centrilobular necrosis, a diffuse inflammatory reaction and some proliferation of the bile-duct epithelium, were similar to those reported in other primates. They differed, however, from those seen in the rat and duckling, in which periportal necrosis is a prominent feature. An extensive outbreak of acute aflatoxicosis in man (apparently the only one so far recorded) occurred in India in 1975. Jaundice, oedema of the peritoneal cavity and lower limbs and severe gastrointestinal bleeding caused a high death rate among a popula- tion subsequently discovered to have consumed maize contaminated with 615.6 pg/g aflatoxin (ibid 1976, 14, ISI).

Some 200 of the survivors of this outbreak of hepa- titis were examined about a year later. monthly checks having been made in the intervening period by means of a reply-card system operated through local Medical Officers (Bhat & Krischnamachari, In- dian J. med. Res. 1977, 66, 55). Following the very high death rate during the acute phase of the illness, a further six deaths occurred during or after the sub- acute phase (between 6 and 8 months after the onset). Jaundice had persisted for 5-7 months in some cases. Among the 70 maize samples collected during the re- survey only seven contained afiatoxin, and then not in excess of 0.1 pg/g. Although these samples con- tained a number of fungi in addition to A. javus. no other mycotoxins were definitely identified. A long-term follow-up designed to demonstrate any change in the incidence of cirrhosis or liver carcinoma in this area would be of considerable interest.

While aflatoxin has been demonstrated in human tissues originating from areas where food storage presents particular problems (Shank et a/. Fd Cosmet. Toxicol. 1971. 9, 501) it is unusual to find reports of aflatoxin in routine human biopsy specimens. However, Phillips et al. (Toxic. appl. Pharmac. 1976. 36, 403) found aflatoxin B, in a concentration of 520 rig/g wet liver in a Missouri resident who suffered from carcinoma of the rectum and liver, with exten- sive hepatic necrosis. No other aflatoxins were detected in the biopsy specimen, but when a homo- genate of the liver tissue was incubated with an NADPH-generating system, the aflatoxin B, recover- able by chloroform extraction was reduced to 250ng/g wet liver and a highly polar metabolite

The question of a possible association between Reye’s syndrome and aflatoxin ingestion (Cited in F.C.7: 1976. 14, 151) continues to evoke interest. A combination of acute encephalopathy with fatty de- generation of the viscera is particularly common in Thailand. where it affects hundreds of children. Many Thai foods contain aflatoxin, and the incidence of the disease corresponds with seasonal and geographical variations of dietary atlatoxin (Harwig et al. Can. med. Ass. J. 1975. 113, 275). Autopsy specimens from 22 of a group of 23 Thai children with this syndrome showed the presence of aflatoxin B,, the highest con- centrations being in the liver (93 rig/g). stomach and intestinal contents (I 27 rig/g). stools (123 rig/g) and bile (8 pg/ml). Harwig et a/. (lot. cit.) point out that oral administration of aflatoxin B, to macaque mon- keys has induced a condition resembling Reye’s syn- drome both clinically and pathologically, while liver extracts from two children in New Zealand and two in Czechoslovakia who died of Reye’s syndrome were shown to contain fluorescent compounds correspond- ing chromatographically with aflatoxins B, and G, and with aflatoxin B,, respectively. Chaves-Carballo et al. (Proc. Staff Meet. Mayo Clin. 19;s. 51, 48) examined liver specimens from eight patients with Reye’s syndrome, from two patients with acute ence- phalopathy without fatty liver. and from ten patients without evidence of liver disease. Thin-layer chroma- tography of liver extracts from I9 of these patients showed no fluorescence indicative of aflatoxins, but the extract from one patient showing the clinical, laboratory and pathological features of Reye’s syn- drome yielded a compound similar to but not identi- cal with aflatoxin B,. The liver concentration of this compound (calculated as aflatoxin B,) was 22.5 rig/g. There was not enough of this compound for further characterization. Hogan et a/. (Lancer 1978, 1, 561) have reported that the blood of two children with Reye’s syndrome contained aflatoxin B, during the acute phase of the disease. Both patients had suffered an initial viral illness and later developed vomiting, hyperventilation, enlarged liver, decerebrate postur- ing, seizures and coma. Their serum concentrations of the aflatoxin were 1 I.93 and 31.3 rig/ml respectively Both children died, and Reye’s syndrome was con- firmed in one post mortem; the other was not autop-’ sied. The information obtained from these post-mor- tem studies. although limited, suggests that further analysis of tissue specimens from victims of Reye’s syndrome would be a worthwhile field of study.

[P. Cooper-BIBRA]