Maximun tolerable concentrations of some mycotoxins: a review

The maximum tolerable concentrations showed in Table 1, are a guidance and have been collected from a combination of scientific published articles concerning to the subject and essays with animals; experiences (40 years) and field observations in the animals about mycotoxicosis ; the legislation and recommendations published by the European Union.

Table 1. Maximum tolerable concentrations (ppb, micrograms/Kg) of some mycotoxins in the complete  feedingstuffs and in different animal species.

* AFB1 = Aflatoxin B1; OTA = Ocratoxin A; ZEN = Zearalenone; DON = Deoxynivalenol or Vomitoxin; T-2 = T2 toxin; DAS = Diacetoxyscirpenol; MAS = Monoacetoxyscirpenol; TAS = Triacetoxyscirpenol; STO = Scirpentriol; FB1 = Fumonisin B1; NA = Non Available

** Several articles indicate that diets contaminated with 2500 and 5000 ppb of AFB1 were given to 23 day old chickens for a period of 32 days. Observations determined no major complications other than slightly friable livers and a reduction of calcium concentration in the serum. Histological lesions were vacuolization of the hepatocytes with infiltration of fat. With age, chickens become more resistant to the toxic effects of aflatoxins (Fernandez et al., 1994; Lanza et al., 1980).

*** Regarding the toxicity of AFB1, could also be established for the bovines, sheep and goats milk producers, a maximum tolerable concentration of 25 ppb. However and  taking into account that the AFB1 is bio-transformed, inside the animal, in aflatoxin M1 (AFM1) and this one goes to the milk, the maximum tolerable concentration for AFB1 in these animals has to be more rigorous, specifically 5 ppb, so that the concentration of AFM1 in the milk does not represent risk for the human consumers of that food (Gimeno, 2005).

**** There was a case in where a concentration of FB1 in complete feedingstuffs so low like 100 ppb during 8 weeks, caused in male pigs a significant erratic growth pattern during the first 5 weeks, the mixed feed consumed was slightly higher than the control group during the first 4 weeks, but decreased 6 to 7% each week afterwards. Male pigs that feed diets with 1000 ppb of FB1 had a decrease in body weight gain of  8%. The authors indicate that, in general, male pigs were more adversely affected by FB1 in the diet than female (Rotter et al., 1996).

Comments

It is very difficult to establish the maximum tolerable concentrations of mycotoxins. There are several factors that can influence (increase or decrease) the toxicity of mycotoxins in animals during the consumption of the contaminated feed. Some of these factors are:  the animal species and breed; the duration of the contamination period (extend of time in which the animals are ingesting the contaminated feed); the animal´s age and sex; the animal´s nutrition and overall health; bacterial, viral, or parasitical infections; inadequate conditions of the animal´s habitat (temperature, moisture, ventilation, handling and others); medication administered; presence of other mycotoxins and synergism or association amongst them.

Therefore, it is a risk to say that there are levels of mycotoxin contaminations that will not cause problems. It is safe to say, however, that there are relatively "safer" levels of contamination.

It is very difficult try to establish guidance values and/or recommendations, because there are certain factors besides the ones before mentioned, that need to be in place, such as: availability of toxicological data; availability of data concerning mycotoxins incidence in the different feeds; homogeneousness of mycotoxins in the feeds (hot spots); availability of analytical methods for control of minimum detectable mycotoxin levels.

The data showed in the Table, can be modified in accordance with the new scientific published articles about mycotoxicosis, and even with the new data collected regarding cases of mycotoxicosis that can appear in the field observations. The before data are a proposal guidance and it is accepted the appropriate criticisms.

Usually, the studies on the fumonisins toxicity are referred to the concentration of FB1, however, the presence of the fumonisin B2 (FB2) together with the FB1 is very frequent.

The  FB2 concentration represents 15 to 35% of the FB1 concentration (Hascheck et al., 2001).

Bibliography

Fernández, A.; Verde, M.T.; Gascon, M.; Ramos, J.; Gomez, J.; Luco, D.F.; Chavez, G. (1994). "Variations of clinical biochemical parameters of laying hens and broiler chickens fed aflatoxin containing feed".Avian Pathology, 23: 37- 47.

 Gimeno, A (2005). "Aflatoxina M1 en la Leche. Riesgos para la Salud Pública, Prevención y Control" e "Aflatoxina M1 no Leite. Riscos para a Saúde Pública, Prevenção e Controlo" en www.engormix.com (Sección: micotoxinas. Areas en castellano y portugués. Articulos técnicos de Alberto Gimeno. Ver listado completo de artículos técnicos) 

Hascheck, W.M.; Gumprecht, L.A.; Smith, G.; Tumbleson, M.E.; Constable, P.D. (2001). "Fumonisin Toxicosis in Swine: An Overview of Porcine Pulmonary Edema and Current Perspectives". In: Environmental Health Perspectives. Vol. 109. Supplement 2, pp. 251-257.

Lanza, G.M.; Washburn, R.W.; Wyatt, R.D. (1980). "Variation with age in response of broilers to aflatoxin".Poultry Science, 59: 282-288.

Rotter, B.A.; Thompson, B.K.; Prelusky, D.B.; Trenholm, H.L.; Stewart, B.; Miller, J.D.; Savard, M.E. (1996). "Response of growing swiene to dietary exposure to pure fumonisin B1 during an eight-week period: growth and clinical parameters". Natural Toxins, 4: 42-50.

This article was previously published in Portal Veterinaria Albéitar

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