Detection of DNA adducts in declining hop plants grown on fields formerly treated with heptachlor, a persistent insecticide.

Hop decline was observed in Alsace, eastern France, in reparcelled sugar beet fields formerly abundantly treated with an insecticide, heptachlor. Leaves were collected from 'declining hops' grown in an heptachlor-contaminated area and from 'healthy hops' grown in a soil not contaminated by heptachlor. These two samples came from hop vines treated with other usual pesticides. 'Control' hop leaves came from soil neither treated with pesticide nor contaminated with heptachlor. Hypermodified nucleotides (DNA adducts) were detected using the (32)P-postlabelling method. No detectable DNA adducts were found in the 'control' specimen, whereas eight adducts were detected in the 'healthy hops' specimen, probably due to the usual pesticide treatment. However, 16 adducts, nine of which were new adducts, could be detected in the 'declining hops' specimen. It may therefore be supposed that the presence of these hypermodified nucleotides perturbs gene expression and so contributes to the hop decline. In addition, to confirm the genotoxicity of heptachlor, it is shown that it induces DNA adducts in bean-cell suspension culture as well. Finally, it is proposed, in the case of alternate cultures scheduled in fields which were formerly treated with pesticides, adapted to other cultures, that particular attention should be given to the history of the soils.

Haloacetic acids, phytotoxic secondary air pollutants.

Haloacetic acids are atmospheric oxidation products of airborne C2-halocarbons which are important solvents and propellants. Levels of trichloroacetate (TCA) in conifer needles from mountain ranges in Germany (Black Forest, Erzgebirge) and from two sites in Finland are compared; TCA is present in conifer needles at concentrations up to 0.7 µmol/kg, MCA up to 0.2 µmol/kg. At the Finnish sites, TCA-concentrations and branch degeneration symptoms of Scots pine are correlated. Monochloroacetate (MCA) has been determined in needle samples from Southern Germany in concentrations exceeding its phytotoxicity threshold towards photoautotrophic organisms. Data on atmospheric chloroacetate levels in Germany are also given; ambient air levels of chloroacetic acids range from about 2 pmol/m(3) (TCA) to 390 pmol/m(3) (MCA). TCA and dichloroacetic acid (DCA) arise from atmospheric oxidation of airborne C2-chlorocarbons, while the source of MCA is not yet known; several tentative pathways are suggested.

DNA adduct detection: some applications in monitoring exposure to environmental genotoxic chemicals.

In the assessment of genotoxic risk factors in the environment, the measurement of DNA adducts in aquatic organisms and in plants may have considerable implications. Using 32P-postlabelling, we have detected DNA adducts in the liver of carp (Chondrostoma nasus) from the River Rhône (France), both downstream and upstream from a polychlorinated biphenyl incineration plant. Some of the DNA adducts were specific to downstream fish, suggesting a differential pattern of exposure. We have also detected DNA damage in needles in a declining spruce forest. We found that, in the declining forest, the amounts of DNA adducts increase in relation to the degree of damage to the needles whereas, in a healthy forest, the levels of DNA adducts were low. We have also found DNA adducts in the leaves of hops grown in fields where heptachlor residues persisted.