Exhibition at Fipronil

Spread the knowledge
  • Exhibition of bees

Beekeepers began to suspect the role of Fipronil following the use of Regent TS for the coating of sunflower seed from 1998 onwards. It gradually became apparent that Fipronil used to treat seeds entered the plant well. (of the order of 5% of the quantity applied) and that measurable traces could be found there. On the other hand, the concentrations likely to be found in nectar and pollen are not yet known , but preliminary observations on bees foraging sunflower flowers from seeds treated with TS Regents seem to confirm the existence of behavioral disorders. An ongoing study of AFSSA(French Food Safety Agency) revealed that in 2003 one could often find traces of Fipronil in the balls of pollen brought back by the bees. Nevertheless no abnormal mortality was observed in the corresponding hives.

The situation became more confused when AFSSA found the presence of Fipronil in pellets of pollen from fruit trees taken from areas where there is no sunflower crop (still without abnormal bee mortality). However, these areas were chosen as control zones, a priori not affected by the problem. This reveals a wider than expected contamination of the environment, but AFSSA researchers are unable to explain its origin and complain that the lack of funds does not allow them to go to beyond these preliminary results.

But the problem was posed in a different way from the complaint of beekeepers of Haute-Garonne and the Gers victims of massive deaths of bees resulting in the disappearance of whole apiaries. In fact, analyzes on bee carcasses revealed that the quantities of Fipronil present could account for acute intoxication with this product . The origin of this important exposure was discussed and the release of Regent dust during sowing with coated seeds was mentioned. Experiments were then conducted with the participation of BASF at the request of the Directorate General for Food. They consisted of dosing Fipronil in the dust emitted by the seed drills.

Two varieties of sunflower seeds from two different suppliers were tested. The results are indisputable: in both cases Fipronil was found in a significant amount in the dust emitted, but one of the varieties releases ten times more Fipronil than the other. This shows the importance of the coating technique used (more or less friability of the coating layer). Seeding trials were also conducted in the field with the most emissive variety. On the perimeter of the field pots of flowering plants or not have been arranged. After sowing these plants were introduced into cages containing experimental hives: very quickly important behavioral disturbances were observed(jolts, inability to fly or stay on the legs …). Undoubtedly the dust emitted during sowing is deposited in sufficient quantity on neighboring plants to poison bees . Values ​​in the order of 150 ng / m 3 would have been measured in dust clouds at the drill, equivalent to a release of 400 mg / ha.

It is therefore clear that the manufacturer ‘s assertion, initially taken up by the Ministry of Agriculture, that Fipronil was buried in the soil could not in any way contaminate the bees or be toxic by inhalation to humans. hold more.

  • Human exposure

Exposure of operators to seed coating companies or the manufacture of Fipronil-based insecticides is a specific problem that will not be addressed here as it depends heavily on the techniques and means of protection implemented in each business. Let us simply point out that the VME (exposure limit value) proposed by Rhône-Poulenc in its safety data sheet for Fipronil is 0.035 mg / m 3 . This value has however not been studied by independent experts. Remember that the VME measures the maximum concentration of a product in the atmospherewhich is supposed to protect the operators of any health disorder for a daily exposure of 8 h / day . This value corresponds approximately to the absorption of 0.125 mg of Fipronil per day in calm respiration, ie 0.0018 mg / kg for a body mass of 70 kg , which exceeds by a factor> 10 the acceptable daily intake ( ADI see definition below). This is all the more worrying as the ADI is established for the digestive tract which is significantly less effective than the airway for Fipronil.

The farmers’ exposure can be done either during the sowing operations or during the filling and cleaning of the seeders. If the above data values are correct they do not imply health risk because dust concentrations would be less than 1/200 th of the ELVs and it is limited operations in time. But two important restrictions are needed. The first is that the VME seems to me too high by at least a factor of 10. The second concerns the concentrations in the dust cloud of seeders: in fact it is not a value of which I found a written trace in a publication, but information transmitted verbally by an intermediary (even if it is a trusted intermediary). The risk of exposure to farmers would therefore require further research. In addition, many other insecticides based on Fipronil are used under various conditions (pellets, sprays, etc.). Each of these uses entails specific risks of exposure, which vary greatly depending on the conditions of implementation of the product.

Various documents raise for example the risk of exposure of veterinarians and pet grooming professionals when they treat these animals against fleas with a product used in spray (Frontline for example). Although these are diluted solutions, this exposure can sometimes be repeated many times during the day.

The other possible route of exposure concerns the public , through residues that may be present in food products . The prevention begins with determining an acceptable daily intake (ADI) . For this we start from the dose without observable adverse effect (NOAEL) determined by animal experimentation: in this case 0.02 mg / kg / day. It is divided by an empirical coefficient, called the factor of safety or the uncertainty factor, to take account of the fact that the speciesselected animal probably does not have the same sensitivity to this toxic as the man and also to take into account that within our species some individuals may be more sensitive than others. In the usual cases this coefficient is 100 , which gives an ADI of 0.0002 mg / kg / day . When the uncertainty on the level of the effects is great one can apply a coefficient more important. For this reason, some experts believe that a factor of 200 should have been applied because of the existence of a mechanism of endocrine disruption and a possible carcinogenic effect .

Subsequently, the acceptable maximum residue limits ( MRLs ) for various foods (based on their share in a typical food ration) must be established. Adherence to these values ​​should ensure an always lower exposure to the ADI. Particular attention should be paid to children who, because of their special dietary needs, are generally significantly more exposed than adults. On the other hand, not being competent in this particular field, I do not know how various probable doses of exposure have been established by various organizations and, in particular, the estimated international daily intake (IEEI).

These assessments are crucial. It is hard to understand why the Director General of Food at the Ministry of Agriculture can say that the use of Fipronil in agriculture poses no risk ”  There is no danger to human health through direct exposure or by the consumption of plant or animal products “, while other experts say that according to the estimates made the estimated dietary exposure is between 43% and 200% of the ADI .

Dr. Kimberly Seltzer

Postdoctoral Scholar, UC Berkeley Research Assistant, MIT

One thought on “Exhibition at Fipronil”

Leave a Reply

Your email address will not be published. Required fields are marked *