Food safety

Latin American total diet studies workshop, Buenos Aires, Argentina, 8 - 13 July 2002

WHO-GEMS/Food and INPPAZ workshop


The total number of chemicals on the market now stands close to 100,000. Out of thousands of chemicals that are produced experimentally each year, one thousand eventually make it onto the market. Many of these chemicals can reach the food supply. In addition, many toxic chemicals occur naturally in food or in the environment. These chemicals can potentially affect all major organs of the body, causing serious health outcomes like cancer, birth defects, and brain damage. Despite this, little attention has been given to assessing the actual dietary intake of these chemicals by humans. One reason is that most of the potential effects of these chemicals are chronic in nature, appearing often years after exposure, and thus cannot be traced to individual foods.

For that reason, it is becoming increasingly important to assess human exposure to background concentrations of a large number of chemicals. The responsibility and obligation to make these assessments usually rests with national health authorities.

To ensure that toxic chemicals, such as pesticides, heavy metals, environmental contaminants and naturally occurring toxins, are not present in foods at levels that adversely affect the health of consumers, two complementary approaches are used. The first is to monitor individual foods for compliance with national and international regulatory standards. The second one is to measure the actual dietary consumption intake of these chemicals by the population, and compare these intakes with toxicological references points, such as the Acceptable Daily Intake (ADI) or Provisional Tolerable Weekly Intake (PTWI). These comparisons provide a direct link to the health of the population, and total diet studies are the most cost-effective and reliable way to estimate the dietary intake of exposure to toxicants by large population groups. Therefore, total diet studies are essential to answer the fundamental question of whether or not the national diet is safe.

A total diet study (TDS) consists of purchasing foods commonly consumed, processing them as for consumption, combining the foods into food composites or aggregates, homogenizing them, and analysing them for toxic chemicals. The analytical results are then combined with food intake consumption information for different population groups, and the dietary intakes of the chemicals by the groups are estimated.

Additionally, the Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) of the World Trade Organization requires that health and safety requirements related to food be based on scientific risk assessments. Risk assessments are based on two essential components: toxicological information and exposure of the population to the chemical. As mentioned above, the latter is most accurately obtained for large population groups using total diet studies. Total diet studies in developing and industrialized countries are necessary to perform risk assessments and ensure that their food safety systems are effective in protecting the public health.