engleski

Organochlorine compounds in human milk and in food from animal origin

Persistent organic pollutants (POPs) are organic compounds resistent to photolytic, chemical and biological degradation. They are characterized by low water solubility and high fat solubility, which results in bioconcentration in fatty tissues of living organisms. In the environment, POPs are present at low levels and can be transported over long distances via water and air. This is why POPs can be found all over the world, including the areas where they have never been used. Organochlorine pesticides (DDT, aldrin, dieldrin, hexachlorobenzene, hexachlorocyclohexane) and polychlorinated biphenyls (PCB) are two groups of POPs intensively used worldwide. Unlike them polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are two groups known as “dioxins” which have never been in practical use. These four groups include over four hundred of compounds; some of them are classified as carcinogens while others are considered as potential carcinogens. Levels of organochlorine compounds in human milk have been monitored since 1976. Initially the investigation was limited to organochlorine pesticides, but later it expanded to total PCBs. The investigation included samples collected from the general population. Samples were collected in Zagreb, Osijek, Labin, Jastrebarsko, Karlovac, Sisak, and on the island of Krk. p,p’-DDE (the main DDT metabolite) and PCB were found in all analysed samples. Other pesticides or their metabolites (a-, b- and g- HCH, HCB, p,p’-DDT, p,p’-DDD) were not found in all samples. No marked differences were found in samples from different geographic areas. A downward trend in the levels was observed: p,p’-DDE levels in human milk were 1900 mg/kg milk fat in 1981/82 and now about six times lower. Over the past twenty years PCB levels in milk have lowered for about three times but it seems that the levels remained unchanged over the past five years. Due to lact of equipment we are not able to perform the “dioxins” analyses in our country. Therefore, the analyses were done in qualified institutions in the USA, the Netherlands, and Sweden. In human milk samples collected in Zagreb, Krk, Jastrebarsko, Labin, and Osijek during the period 1981–1997 the “dioxins” levels were in the range 8.4–26.7 I-TEQ ng/kg milk fat (expressed as TCDD toxic equivalents according to international toxicity factors). A comparative study organized by the World Health Organization showed a 1.8% annual decrease of “dioxins” levels in samples collected in Zagreb and Krk in 1992 with respect to 1987, while other European countries and Canada showed a 7.2% decrease. One may wish to note that the levels in milk samples collected in Croatia were within the lower half of the concentration range determined in samples from other European countries, Canada and Pakistan and it would not be reasonable to expect that the Croatian samples show a similar drop in “dioxins” levels. The analysis of organochlorine compounds in food from animal origin (milk, butter, beef, pork, poultry, fish) shows that p,p’-DDE and PCBs are present in almost all analysed samples. The highest levels of analysed compounds were found in fish and are not dependent on the origin of fish. The comparison of results obtained over a longer period showed a downward trend in levels what is the result of restriction of their use. The daily intake of organochlorine compounds was evaluated for breast-fed infants from the levels in human milk and for adults from the foodstuff analysis. It was found that the intake by the adult population in our country was below the acceptable daily intake values. This is not the case with the breast-fed infants whose daily intake was sometimes higher than the ADI values. The same situation is in other countries in the world, particularly in highly industrialized countries or in those where organochlorine pesticides are still in use. It seems that the population of breast-fed infants is more exposed than the adults, but one should keep in mind that the breastfeeding period is short in relation to the whole life, and that the benefites of brestfeeding prevail over the risk of the intake of organochlorine compounds. To sum up: our investigations show that levels of organochlorine pesticides, polychlorinated biphenyls and “dioxins” in our populations are within the lower half of the concentration ranges reported worldwide.

Organochlorine pesticides;PCB; PCDD; PCDF; human milk; food

nije evidentirano