The use of synthetic pesticides (in agriculture, in garden or in green spaces) can have an impact on fauna and flora:
- Direct: the disappearance of animals (fauna) by direct ingestion of the product (example of birds that can ingest the coated grains of the product).
- Indirect: polluted vital resources – water or food, the disappearance of species leading to a reduction in the food reserves of other species, ingestion of contaminated food itself, etc.
In addition to the danger of death due to direct and indirect ingestion of pesticides, wildlife can:
- Develop certain pathologies such as cancers.
- Having abnormal thyroid function.
- Have decreased fertility.
- Have a feminization of the reproductive organs for males.
- Encounter a disruption of the immune system.
Amphibians
Many studies highlight thereduction in the abundance of certain populations, or even the total disappearance of certain species (Houlahan et al., 2000; Alford et al., 2001). Amphibians are considered particularly sensitive to many pesticides.
Amphibian declines in Californiaare associated with the use of organophosphates and other pesticides in nearby areas (Aston & Seiber, 1997; Davidson et al., 2001; Sparling et al., 2001).
Endocrine Disruptors Problem: Effects of atrazine are noted on endocrine and reproduction in amphibians (see e.g. Hayes et al., 2002a, 2002b, 2003; Tavera-Mendoza et al., 2002a, 2002b). At very low concentrations (0.1 μg/L) = gonad abnormalities and demasculinization (Hayes et al., 2002a, 2003).
A study (Hecker et al. (2004) in 2 regions of South Africa highlights a difference depending on the intensity of maize cultivation and the use of triazines. Showed lower plasma concentrations of testosterone and estradiol in female xenoops in intensive areas.
Mammals
The state of play of the relationship betweenpesticide use and the evolution of bird populations is also valid in the case of mammals, although it is less documented. Here are some examples of studies and impacts that have been demonstrated:
- Brown (1999, in Hole et al., 2005) observedincreased activity of small mammals in biological systems. The higher abundance of insect populations in biological systems is cited to explain this phenomenon.
- Abnormal mortalities and a lower population inGrey-tailed Volesafter exposure in plots treated with a pesticide.
- Bats: 61-84% increase in activity in organic crops Wickamasinghe et al. (2003, in Hole et al., 2005)
- Decline inhare numbers, ranging in intensity from a few percent to almost 50% depending on the European country considered, has been recorded over the last 40 years.
- Cases of bromadiolone poisoning offoxeshave been identified (see for example Berny et al., 1997), and the hypothesis of the role of consumption of animals poisoned by this anticoagulant is fully corroborated by experimental studies.
- Dogs: increased risk of developing certain cancers (spleen in particular) for dogs that have been exposed to insecticides. Risk 3.5 times greater if the animal was exposed 2 or more times per year. Journal of Toxicology and Environmental Health; 28 (4). 1989. 407-414 and Journal of the American Veterinary Medicine Association, April 15, 2004
Birds
Evenvery low levels of pesticide residuesin food consumed by vertebratescan lead to death. Formulated pellets or treated seeds also represent a greater risk of ingestion when they can be used by birds as food or as grinding particles. Incidents involving carbamate pellets are thus common (Mc Laughling & Mineau, 1995). Pigeon mortalitiesassociated with the ingestion of coated pea seed also demonstrate the existence of this route of exposure under normal conditions of pesticide use. Here are some examples of studies conducted and impacts found:
- The overall decline of cropland-associated bird populations in Western Europe. Monitoring was carried out on farms in Denmark (31 conventional and organic farms). Decline has been proven for 15 of the 35 common species observed, in proportion to the amount of pesticides used (Braae et al., 1988 in Mc Laughling & Mineau, 1995).
- A higher abundance in the biological system for 31 of the 34 species observed in the study Hole et al., 2005.
- Other impacts of pesticides: secondary poisoningand reduction of food resources.
- Decrease in the sparrow or lark populationby 60% over the last 25 years in both France and England.
- For 11 of the 12 species for which a start date for population decline could be estimated, it has been shown that theonset of decline coincides with a period of massive use of pesticides, including herbicides (Liess et al., 2005).
- 13 of the 20 speciesthat have declined the most in France in the last twenty years are species found in agricultural areas…
Pisces
Numerous publications and books have been devotedto the danger posed by pesticides to fish. This work mainly refers to acute toxic effects.
Among pesticides, pyrethroids are probably the most dangerous substances for fishfrom the point of view of their acute toxicity.
Some pesticides or pesticide derivativesexhibit endocrine disrupting properties in fish (review in Arukwe & Goksøyr, 1998 and Brown et al., 2001).
Observations in the wild have shown thatsome freshwater or estuarine fish populations have abnormalities likely to have been induced by endocrine disruptors (intersex, sex reversal, etc.); see, for example, Jobling et al., 1988; Minier et al., 2000; van Aerle et al., 2001; Pickering & Sumpter, 2003; Beresford et al., 2004),
If water quality continues to improve, specialists issue analert to the pesticide-drug cocktail (source: fridolin wichser November 11, 2005)
The presence of micropollutants in water is worrying Thus, Robert Cramer (Geneva State Councillor) at the International Commission for the Protection of Lake Geneva Water (CIPEL) declares:
« Water quality is improving, but in our rivers, fish are changing sex or catching serious diseases. There is a strong presumption that this chemical cocktail has something to do with it. However, the nature of the problem must first be understood before it can be solved.»
Observation after analysis of the lake: presence of about thirty pesticides. The two main ones came from the Valais chemical plants: Syngenta, in Monthey, and Lonza, in Visp.
« These products tend to accumulate when they are supposed to be biodegradable. Known in the laboratory and at room temperature, their reaction is not in the dark and cold waters of the lake,” worries Marc Bernard, of the Valais Service for Environmental Protection.
Reptiles
The scientific literature shows alarge decline in certain species (snakes and alligators) in regions subject to massive pesticide applications (Fleet et al., 1972, Fleet & Plapp, 1978 and Guillette et al., 1994, in Guillette, 2000). ). Dead or dying animals have been found at sites immediately after treatment (Koeman et al., 1978)
A review by Hall (1980, in Pauli & Money, 2000) highlightedthe impact that certain pesticides, particularly organochlorine substances, could have onreptile populations, by inducing mortalities, even at recommended doses of use.
In Ukraine, monitoring conducted following aerial applications of malathion on forests has revealedabnormal mortalities in reptiles (Karpenko & Myasoedov, 1978, in Pauli & Money, 2000).
Various scattered observations reportthe death of individuals exposed either during treatment or by ingestion of contaminated food for various molecules (DDT, endosulfan, dieldrin, chlorpyrifos, cyanophos; review in Lambert, 1997).
Herbicides 2,4,5-T and 2,4-D have inducedimpacts on turtle populations in Greece (Willemsen & Hailey, 1989). Willemsen & Hailey (1989) observed a 44% decline in turtle populations in Greece, giving it the same potential impact as 2,4-D.
Inalligator and turtle populations, mortality and the incidence of deformities are generally higher in populations exposed to certain compounds (DDT, DDE and dieldrin) than in unexposed populations.
Plants
It is estimated that theplants present in the fields have decreased by more than 20% and that more than 15% of the national plant heritage is endangered. This makes some scientists say that: “the era of the great extermination of plants is underway and an ecological vacuum is being created by man” J. KORNAS
Some non-cultivated plants (or “weeds”) are threatened with extinction in Britain (Preston 2002).
- Many plants thatt were once common in Britain’s agricultural areas are in decline due to the abandonment of mixed farms and the increasing use of herbicides.
- The widespread use of sulfonylurea herbicides, and presumably also sulfonamides and imidazolinones, poses a risk to non-target plants, algae, and ecosystems.
- Triazine herbicides may pose a risk to non-target plants and aquatic plants.