The storage levels of DDT and its metabolites, following the long term administration of technical DDT at the dose levels of 2, 20, 50 and 250 ppm to mice, were evaluated in the fat tissue, liver, kidney, brain and reproductive organs. In addition, storage levels were evaluated in foetuses and newborns of DDT-treated mothers. Apart from op'-DDT, there was a direct relationship between the concentration of each metabolite in each organ and the dose to which the animal was exposed. The highest concentration of DDT and metabolites was found in the fat tissue followed by reproductive organs, liver and kidney together, and lastly brain. The most prevalent metabolite was pp'-DDT, except in the liver, where pp'-DDD showed the highest concentration. Pregnant females had lower concentrations of all metabolites than non-pregnant females. The concentration of residues in samples of total foetal litters was directly related to the concentration of DDT fed to the mother. There was a strong negative correlation between the concentration of pp'-DDT and that of pp'-DDD in the foetuses and the placentas of the same litter. A significant increase in whole body DDT concentration was observed shortly after birth.

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1 The concentrations of some organochlorine pesticides and polychlorobiphenyl compounds have been determined in 102 samples of human milk collected between January 1979 and September 1980. 2 Comparison of the results with those from a limited study undertaken in 1963-4 shows a decline in residues' levels. 3 The concentrations of organochlorine pesticides and polychlorobiphenyls in human milk samples from residents in Great Britain compare favourably with data obtained in other countries.

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results from earlier studies showed a further decline in residues of pp'-dichlorodiphenyltrichloroethane (pp'-DDT) and dieldrin (HEOD) and increased amounts of hexachlorobenzene residues; concentrations of other compounds were similar to those observed in the studies carried out in 1963-4, 1965-7, and 1969-71. Comparison of the data with those from other countries showed that the concentrations of organochlorine pesticide residues and polychlorobiphenyls in human fat samples from residents of the United Kingdom remain among the lowest in Europe and, indeed, the world.

Residue levels of organochlorine pesticides, organophosphorus pesticides, fumigants and bromide were determined in home‐produced and imported wheat during the period October 1978 to April 1979. A total of 281 samples was analysed of which 133 contained low levels of carbon tetrachloride, 112 contained low levels of gamma‐HCH and 26 contained low levels of malathion. One sample contained a residue of carbon tetrachloride, and another a residue of 1,2‐dichloroethane, both of which were above the Codex Alimentarius guide‐line levels. No other residue approached the proposed Codex Alimentarius maximum residue limits.