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Background

Environmental contamination - caused by the changes and influences of human activities (industrial and agricultural production, accidents, traffic etc.) - spreads over the borders of countries. Problems associated with the political and economic reforms in the Countries of Central and Eastern Europe (CEE) include environmental degradation with serious consequences on human health. Environmental data and expert analyses show that a number of remaining problems and emerging concerns were identified in the CEE. Chemical pollution, with regard to organic substances presents the major remaining problem. Previous extensive industrial production (e.g. PCBs) and accidents resulted in large-scale pollution or in some specific ecochemical problems in several areas. On the other hand, environmental pollution is assumed to play an important role in the high cancer rate in the CEE. Cancer rates in adult males have been rising and are now in some countries more than twice of those in western European countries in some age groups. Therefore one of the priorities is to contribute to solving the problems mentioned above, with particular emphasis on research in environmental health which is of mutual interest. Co-operation in this sector will help to create the basic conditions for improving environmental protection and population's health.

Research into methods of sampling, sample storage, analysis and comparability of environmental data, and improvements in the methods of monitoring with a direct impact on human health as well as HUMAN HEALTH RISK ASSESSMENT are extremely needed. The western countries are coping with this problem, but in the CEE countries due to lack of funds, expertise and sophisticated equipments the situation is not yet under control.

Risk assessment may be seen as a complex process which involves extrapolation of toxicity data from animal studies to humans and the use of default assumptions in areas where information is incomplete. This process is a scientific attempt to identify and estimate true risks. The approaches and methods used in dietary risk assessment continue to be revised as more information becomes available. There are normally four stages in this, as follows:

Hazard identification (What are the substances of concern and what are their adverse effects ?),
Dose - response relation (What is the relationship between the dose and the frequency of the effect?),
Exposure assessment and
Risk estimation.

The potential exposure of humans to pesticide residues in foods can be estimated by determining the types and amounts of food eaten and the levels of residues in the food. There are three main assumptions for creating a reliable food consumption and pesticide residue database.

    1. (a) Food consumption data should be surveyed periodically, (b) Consumption of infants and children should be considered in age intervals - nursing infants, children up to age 5, and two separate subgroups for age 5 to 10 and 11 to 18 years old.
    2. Samples should be analysed for both the pesticide and its degradation products at the levels of health concern. The samples may be analysed by either multiple- or single-residue analytical methods depending on the type of monitoring program. Since most monitoring program data are designed for enforcement purposes, the detection limits have historically been set relative to the tolerance levels. These detection limits, however, may not be sufficiently low for dietary risk assessment.
    3. More representative samples of processed foods consumed by infants should be monitored. Use of market basket or total diet studies provides the best estimates for chronic dietary intake of pesticide residues. The results of such studies should generally displace other estimates.

Taking into account the complexity and importance of the problems dealing with the exposure of the sensitive child's organism to persistent organochlorine compounds, no generally acceptable system was presented till now. Especially the benefits and limitations of breast feeding have given rise to considerable concern among paediatricians, who must weigh possible and potential hazards against the many beneficial effects.

Breast milk is usually considered the right balance of fully utilised nutrients required for a growing, full term infant. The existence of host -resistant factors in human milk gives the infant immunologic protection. In addition, the presence of food antibodies in human milk may prevent food allergies. Another important consideration is the emotional bonding that normally develops between mother and infant during nursing. Finally, an economic advantage, especially in the Third World, is that breast - feeding offers the cheapest means of feeding an. infant.

The major contraindications against breast-feeding are the possible transfer of infectious organisms in the milk from infected mothers, presence of drug residues in the milk, or contamination of the milk by environmental or occupational chemicals. The chemical contamination of the milk by organochlorines is the subjects of the present case-study.

The first recognition that breast milk may be contaminated by environmental chemicals came in 1951. These findings showed that the milk from normal and healthy black American women contained considerable amounts of the organochlorine insecticide DDT. Since then, many investigations on contamination of human milk have been made all over the world, and DDT, together with some other organochlorine pesticides, has been detected and determined in most of these investigations. Since the discovery of PCB as environmental pollutants in the late 1960s, PCB s have also been found in most samples of breast milk. Until now the contaminants found most frequently in breast milk have been DDT, its main metabolite DDE, PCB, hexachlorobenzene, dieldrin, and heptachlor epoxide.

Most contaminants found in human milk are lipophilic substances which will be detected mainly in the fatty phase of the milk. Low exposure to environmental chemicals can also be reflected in breast milk if these substances have a high degree of environmental and metabolic persistence and ability to be bioaccumulated in organisms and biomagnified through food chain. In fact, milk secretion is the most important route of excretion of those types of persistent compounds in humans. From this point of view breast milk studies offer feasible and relevant supplements to current biological monitoring and may also be used as a human monitoring tool. By combining sampling with a questionnaire completed by a donor, it is also possible to discover risk factors or chemical exposures of importance. On the other hand, breast milk may be used as a tool for total diet study for whole nursed children. This method enables the most exact exposure assessment to persistent organochlorines by infants.