IARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC ...

1.5 Regulations and guidelines
AFLATOXINS 193
Efforts to reduce human and animal exposure to aflatoxins have resulted in the establishment
of regulatory limits and monitoring programme worldwide. The rationale for
the establishment of specific regulations varies widely; however, most regulations are
based on some form of risk analysis including the availability of toxicological data,
information on susceptible commodities, sampling and analytical capabilities, and the
effect on the availability of an adequate food supply (Stoloff et al., 1991). In 1995,
among countries with more than five million inhabitants, 77 had known regulations for
mycotoxins (all of which included aflatoxins) and 13 reported the absence of regulations.
Data were not available for 40 countries (FAO, 1997). The regulation ranges for aflatoxin
B 1 and total aflatoxins (B 1, B 2, G 1, G 2) were ‘none detectable’ to 30 or 50 μg/kg,
respectively. Seventeen countries had regulations for aflatoxin M 1 in milk. The regulatory
range for aflatoxin M 1 in milk was ‘none detectable’ to 1.0 μg/kg. New minimum
EU regulations to which all EU countries must adhere were provided in 1998 (European
Commission, 1998b). These regulations apply to all aflatoxins (B 1, B 2, G 1, G 2) in raw
commodities and processed foods and to aflatoxin M 1 in milk. Regulations for other
commodities include infant foods (European Commission, 2001) and selected spices
(European Commission, 2002).
The Codex Alimentarius Commission (1999) is considering a recommendation to
establish a limit for aflatoxins in foods of 15 μg/kg of total aflatoxins for all foods
worldwide.
2. Studies of Cancer in Humans
Beginning in the 1960s and throughout the 1980s, a large number of ecological
correlation studies were carried out to look for a possible correlation between dietary
intake of aflatoxins and risk of primary liver cancer (IARC, 1993). Most of these studies
were carried out in developing countries of sub-Saharan Africa or Asia, where liver
cancer is common. With some notable exceptions, and despite the methodological limitations
of these studies, they tended to show that areas with the highest presumed aflatoxin
intake also had the highest liver cancer rates. However, the limitations of these
studies, including questionable diagnosis and registration of liver cancer in the areas
studied, questionable assessment of aflatoxin intake at the individual level, non-existent
or questionable control for the effect of hepatitis virus and the usual problem of making
inferences for individuals from observations on units at the ecological level, led to
increasing recognition of the need for studies based on individuals as units of
observation.
In the 1980s, some case–control studies were carried out in high-risk areas, generally
based on reasonably reliable diagnostic criteria for liver cancer (IARC, 1993). The
comparability of cases and controls was limited in some of these studies. Exposure to