Fungicides

„Geschafft!“, sagt Friedrich Haalck und klappt den Deckel seines druckfrischen Buches zu. Der Leher ist zufrieden mit dem, was er in mehr als dreijähriger Arbeit recherchiert und aufbereitet hat. Jetzt muss seine Botschaft nur noch in der Landwirtschaft ankommen: Auf Pestizide komplett zu verzichten.
Das, was der Bauerssohn unter dem Titel „Pestizide, nein danke!“ wissenschaftlich aufbereitet und leicht verständlich auf 165 Buchseiten zusammengefasst hat, lässt mehr als aufhorchen. Es geht um die Verwendung von Giften, Pestiziden, in der Landwirtschaft. „Der gezielte Chemiekalieneinsatz, die sogenannte Sikkation, hat sich in den vergangenen Jahren auch in Dithmarschen breit gemacht, weitgehend unbemerkt von der Öffentlichkeit“, sagt Haalck.

Wissenschaftler des des Instituts für Umweltwissenschaften Landau weisen jetzt nach, dass die mathematischen Modelle zur Bestimmung der Gefahr durch Pilzgifte, die Realität nicht widerspiegeln. Alarmierendes Ergebnis: „In bis zu vier von zehn Fällen war die tatsächliche Belastung der Gewässer höher als vorausberechnet.“ Knapp die Hälfte aller in der EU eingesetzten Pflanzenschutzmittel seien Fungizide, beschreiben die Wissenschaftler der Universität Koblenz-Landau den Anlass für ihre Studie. Bauern spritzen die Gifte „regelmäßig in größeren Mengen“, sagen die Wissenschaftler und wissen: „Etwa bei Regen werden die Mittel in Flüsse und Seen geschwemmt, wo sie in höheren Konzentrationen Effekte auf Tiere und Pflanzen hervorrufen können.“ Viele Fungizide wirkten nämlich nicht spezifisch gegen Pilze, sondern „verhindern allgemeine Prozesse in Zellen wie die Energieproduktion oder deren Teilung“.

The method used to approve pesticides in the EU needs to be revised. This was confirmed by a recent study by the Institute for Environmental Sciences Landau. According to the study, the level of fungicides measured in surface waters is often much higher than the level predicted by the current calculation model used in the approval process. Last year a study by the Institute on insecticides had a similarly alarming conclusion.

Rising levels of cancers and fertility problems have attracted scientists’ attention to endocrine disrupting chemicals, with some calling for strict regulation of the substances, in line with the precautionary principle. Others meanwhile, stress the worthiness of those chemicals in everyday products such as plastics and warn that the foundations of science risk being turned upside down if precautionary measures are taken. Endocrine disruptors are suspected of triggering diseases such as cancer or diabetes and contributing to people becoming overweight or infertile. The controversy has gone beyond the traditional confrontation between the chemicals industry and environmental and health activists. Among scientists, too, opinions vary on whether a link exists between these chemicals and diseases. But all parties agree on one point – that the protection of consumers and the environment must be ensured. Henk Tennekes comments that a new risk assessment is needed to evaluate the effects that chemicals have on humans and the environment and that endocrine disruptors may be a case in point.

Most literature on birds and rice (Oryza sativa) focuses on the non-growing period and little is known about the influence of management practices during cultivation. A review found that the main factors affecting species composition and abundance in rice fields during the growing season were water level, flooding period, rice plant structure and size, and pesticide use. Highest bird density and diversity occurred at intermediate water levels (10–20 cm). Early flooding and late drying favored waterbird density and diversity, and the stopover of migrating species. Taller plants, at higher densities, reduced prey availability to most waterbirds but favored smaller species. Pesticides and herbicides have been shown to be toxic to birds and reduce food resources.

During the past 50 years, the human population has more than doubled and global Agricultural production has similarly risen. However, the productive arable area has increased by just 10%; thus the increased use of pesticides has been a consequence of the demands of human population growth, and its impact has reached global significance. Although we often know a pesticide´s mode of action in the target species, we still largely do not understand the full impact of unintended side effects on wildlife, particularly at higher levels of biological organization: populations,
communities, and ecosystems. In these times of regional and global species declines, we are challenged with the task of causally linking knowledge about the molecular actions of pesticides to their possible interference with biological processes, in order to develop reliable predictions about the consequences of pesticide use, and misuse, in a rapidly changing world.

A study investigated whether cytogenetic damage increased through prolonged pesticide exposure in n = 117 children, aged 7-11 years, living in rural areas of intensive agriculture; controls being n = 87 children from an agri-tourism region without pesticide exposure. DNA Single-Strand Breaks (SSB) were detected by the Comet assay in whole fresh blood samples together with ‘formamidopyrimidine DNA-glycosylase (FPG)-sensitive sites' with the bacterial FPG protein in isolated lymphocytes. Micronuclei (MN) levels were measured by the cytokinesis-block MN assay. Acetylcholinoesterase (AChE) and Pseudocholinesterase (PChE) activities were used as biomarkers of exposure. Subjects exposed to pesticides had significantly higher AChE and PChE activities than controls, although average levels were well below the biological exposure limit. In addition, those exposed to pesticides had significantly higher levels of steady-state FPG sites and SSB levels (p < 0.001), as well as MN levels. A positive correlation was found between PChE activity and FPG-sensitive sites and also between MN levels and FPG-sensitive sites, (both p < 0.01). In conclusion, despite the relatively low pesticide exposures in the test group of children, significant biological/developmental effects were detected.