Accumulation of weathered p,p'-DDTs in grafted watermelon

How Do Modern Pesticide Treatments Influence the Mobility of Old Incurred DDT Contaminations in Agricultural Soils?

Even more than 50 years after the ban of DDT in Germany, farmers are still affected by its persistence in contaminated soils. Depending on the crop cultivated on such soils, this often leads to low-level residues of DDT and its metabolites DDE and DDD ("DDX"), which are perceived as a risk by the food value chain. Pesticide formulations used in modern agriculture commonly contain high levels of surfactants, but so far no open-field studies have evaluated the effects of these treatments on the mobility of lipophilic contaminants, such as DDX. In this field trial, a 1.03 ha section was cultivated with Cucurbita maxima under realistic conditions to monitor the mobility of DDX in low-level contaminated agricultural soils in dependence of common pesticide applications. A typical organic treatment was compared to a conventional protocol. Soil samples were taken before and after each application. Samples from the organic section featured significantly higher extractable DDX contents in soil and water compared to the conventional section. The results show that modern pesticide treatments can have an unforeseen, yet significant influence on the mobilization and, subsequently, on the plant bioavailability of incurred DDX residues depending on the formulation composition.

The Red Blood Cell Acetylcholinesterase Levels of Depressive Patients with Suicidal Behavior in an Agricultural Area

Long-term exposure to organophosphate pesticides (OPs) without acute poisoning can lead to various OPs. Environmental exposure to organophosphate pesticides may be associated with depression and suicide attempts in a population living in a rural agricultural area. Patients (n = 149) suffering from major depressive disorder (with and without attempted suicide) and a control group of healthy individuals (n = 64) who had been living in the same rural district for at least 1 year were selected. Red blood cell acetylcholine esterase (RBC-AChE) activity was examined as the basis of evaluating the degree of chronic environmental exposure to OPs residues. There were negative association between RBC-AChE activity levels and suicide attempts, the number of past suicide attempts and hopelessness levels in the depressive patients. The results of the study may support the idea that environmental exposure to OPs may be associated with mental health in individuals living in agricultural districts who are not farmers or working in occupations with access to OPs.

Structural and functional alterations induced by two sulfonamide antibiotics on barley plants

Synthetic veterinary medicines are introduced routinely in the environment after animal treatment to prevent and control infectious diseases and up to 80% the administered dose can be excreted unaltered. As a consequence, the soil is the environment most contaminated by such molecules. However, information about their implications on the growth of vegetal organisms is still scarce. With the aim of better elucidating the effects of veterinary antibiotics on plants, barley was grown in a nutrient solution containing 40 μM (about 11,500 μg L(-1)) of two well-known sulfonamide antibiotics, sulfadimethoxine (SDM) and sulfamethazine (SZ). After 15 d of treatment, the effects on root apparatus were particularly evident, while the photosynthetic tissues remained almost unaffected. SDM and SZ stimulated root hairs and lateral root development a few mm behind the root tips. In particular, from a structural point of view, treated plants showed root shortening and an advanced differentiation in comparison to controls, later confirmed using light microscopy. At a functional level, the two active molecules were found to induce root electrolyte release, such as K(+), possibly due to an impairment of membrane permeability. The research concludes that sulfonamides can have profound effects on morphology and functionality of roots of crop plants. As these alterations might have consequences on their productivity, further studies are necessary to assess effects on plants at laboratory and field conditions.

Inheritance profile of weathered chlordane and p,p'-DDTs accumulation by Cucurbita pepo hybrids

Cucurbita pepo ssp pepo (zucchini) accumulates significant levels of persistent organic pollutants in its roots, followed by unexpectedly high contaminant translocation to the stems. Most other plant species, including the closely related C. pepo ssp ovifera (squash), do not have this ability. To investigate the mechanism of contaminant accumulation, two cultivars each of parental zucchini and squash, as well as previously created first filial (F1) hybrids and F1 backcrosses (BC) of those parental cultivars, were grown under field conditions in a soil contaminated with weathered chlordane (2.29 microg/g) and DDX residues (0.30 microg/g; sum of DDT, DDE, DDD). The parental zucchini had stem-to-soil bioconcentration factors (BCF, contaminant ratio of stem to soil) for chlordane and DDX of 6.23 and 3.10; these values were 2.2 and 3.7 times greater than the squash, respectively. Chlordane and DDX translocation factors, the ratio of contaminant content in the stems to that in the root, were 2.1 and 3.2 times greater for zucchini than for squash. The parental zucchini and squash also differed significantly in chlordane component ratios (relative amounts of trans-nonachlor [TN], cis-chlordane [CC], trans-chlordane [TC]) and enantiomer fractions for the chiral CC and TC. Hybridization of the parental squash and zucchini resulted in significant differences in contaminant uptake. For both the three separate component ratios (CR) and two sets of enantiomer fraction (EF) values, subspecies specific differences in the parental generation became statistically equivalent in the F1 hybrid zucchini and squash. When backcrossed (BC) with the original parental plants, the zucchini and squash F1 BC cultivars reverted to the statistically distinct CR and EF patterns. This pattern of trait segregation upon hybridization suggests either single gene or single locus control for persistent organic pollutant (POP) uptake ability by C. pepo ssp pepo.

Accumulation of weathered p,p'-DDTs in hybridized Cucurbita pepo cultivars

Cucurbita pepo spp pepo (zucchini) is known as an exceptional weathered dichlorodiphenyldichloroethylene (DDE) accumulator, whereas Cucurbita pepo ssp ovifera (squash) is termed a nonaccumulator. Experiments were conducted with hybridized zucchini and squash to assess the inheritance pattern of DDX (the sum of p,p'-dichlorodiphenyltrichloroethane [p,p'-DDT], p,p'-dichlorodiphenyldichloroethane [p,p'-DDD], and p,p'-dichlorodiphenyldichloroethylene [p,p'-DDE]) accumulation potential in xylem sap and tissues of parental, F1 hybrids, and F1 backcross (BC) generations of plants. Plants were grown in pots containing soil with weathered DDX at 732 to 1,130 ng/g soil or under field conditions in soil with 322 to 2,700 ng/g. The DDX stem bioconcentration factors and xylem sap values showed differences between parental and hybridized plants of squash and zucchini. For squash grown in greenhouse conditions, the DDX flow rate in the xylem sap was 17.3, 121, and 40.8 ng/h in parental, F1 hybrids, and F1 BC plants, respectively. Similarly, the stem DDX content of parental, F1, and F1 BC squash was 11, 253, and 96 ng/g (dry wt), respectively. A similar inheritance pattern for squash was observed when the plants were grown under field conditions. The DDX flow rates in the xylem sap of pot-grown parental, F1, and F1 BC zucchini cultivars were 100, 8.5, and 26 ng/hr, respectively, and the stem DDX content was 191, 102, and 142 ng/g, respectively. Again, similar trends in accumulation potential were observed for hybridized zucchini grown under field conditions. The DDX concentrations in parental plants matched the expected pattern, with hybrids midway between the two species, and the backcross being more like the parent again for both species. This inheritance pattern of contaminant accumulation and translocation ability follows classical Mendelian segregation and suggests single-gene or single-locus control.