It warns that in the worst-case scenario where key approval criteria are defined widely, the implications for horticulture are serious.
The latest estimate is based on amendments made by the EP's environment committee (known as ENVI) to the European Council common position during the proposals' second reading in the EP last month.
While the figures compare favourably with the PSD's original estimate that up to 85 per cent of chemicals were at risk from the EP's proposals at first reading, the situation remains very serious for certain crop sectors.
As the PSD assessment later notes: "It is clear that it is not simply the percentage or absolute numbers of substances that might be lost which is the most important factor, but the particular substances concerned."
Such significant changes between the two assessments stem largely from two things: firstly, that the EP's environment committee no longer proposes to change the criteria for identifying candidates for substitution; and secondly, that the environment committee has clarified it was not its intention that approval for candidates for substitution should not be renewable.
However, the picture continues to be complicated by the lack of a definition within the European Council common position for endocrine disruptors - one of the key criteria proposed for non-approval of chemicals. If the definition is limited to chemicals that can damage the reproductive system (known as category 3 reproductive toxins), then the potential loss falls slightly to between nine and 21 per cent.
Amendments proposed by the environment committee to the criteria for approval in addition to the council common position include "addition of an example (category 3 reproductive toxins) for what might be considered an adverse effect in humans for endocrine disruptors". Further criteria "are to be adopted 18 months after entry into force of the Regulation" (see panel).
Meanwhile, the EP's environment committee has included two criteria - on developmental neurotoxicity and immunotoxicity - which according to the PSD "are particularly difficult to assess".
The PSD said: "We had previously assumed that no substances would be affected by these criteria because the other criteria were assessed to have such a broad impact. However, with the proposed changes from the ENVI, these criteria have potentially become more significant and a more detailed consideration is required."
Using substances defined in a recently published paper, the PSD estimates that the inclusion of criteria on neurotoxicity will mean the loss of around 12 per cent of those assessed, hitting mainly insecticides. However, it notes: "We have not been able to find a realistic basis on which the impact of the criteria on immunotoxicity could be assessed at this stage."
Other criteria include POP (persistent organic pollutant), PBT (persistent, bioaccumulating, toxic) and vPvB (very persistent, very bioaccumulating), which "remain difficult to assess without the full guidance in place".
The report concludes that the loss of active substances from the common position, assuming the widest definition of endocrine disruptors is to be applied, would have serious implications "in both agriculture and horticulture".
Under this scenario there would be "significant" implications for minor crops such as carrots, parsnips and onions, because the majority of currently approved herbicides may no longer be available. The PSD said there was potential for up to 100 per cent yield loss on carrots.
Even with a tighter definition of endocrine disruptors in place, for horticultural crops and potatoes the loss of mancozeb "will impact seriously on resistance management", the PSD said. In addition, loss of some important triazoles "would potentially seriously affect disease control on many crops".
In herbicides, the PSD said there is "some amelioration in terms of the active substances available with some significant products being retained". However, the substantive impact across both cereal crops and many minor crops, where pendimethalin and linuron are very important, will not be changed.
The introduction of cut-off criteria for developmental neurotoxicity and other criteria as proposed by the EP has potentially a very significant impact on the availability of insecticides and could lead to significant control issues in some circumstances, the report finds.
The PSD said in the report: "There is potential for increased impact from loss of herbicides in cereals and in rotational horticultural crops as well as increased cost of weed control in grassland."
However, the most significant impact is the loss of several groups of insecticides, notably the pyrethroids, carbamates and organophosphorous compounds.
"For some targets, such as nematodes, there are no alternative treatments. This will have profound consequences for the production of potatoes, and also for carrots and onions."
Meanwhile, the PSD added, the increased resistance risk associated with the loss of these compounds in major aphid species "is a significant concern".
Finally, the possible loss of methiocarb, one of two major active ingredients used for the control of slugs, is another key concern. "Slugs are one of the most intractable problems facing UK agriculture and horticulture," the PSD said.
SUMMARY OF AMENDMENTS
Amendments proposed by the European Parliament's environment committee to the criteria for approval in addition to the council common position:
- Addition of an example (category 3 reproductive toxins) for what might be considered an adverse effect in humans for endocrine disruptors. Further criteria are to be adopted 18 months after entry into force of the Regulation.
- No substances considered to cause a significant risk of developmental neurotoxic or immunotoxic properties (affecting one in one million) in humans, unless exposure is "negligible".
- Extension of PBT (persistent, bioaccumulating, toxic) and vPvB (very persistent, very bioaccumulating) criteria to transformation products and residues.
- Exposure to bees is either negligible or established through a risk assessment to have no unacceptable effects.
- No substances on priority hazardous list for water in the Water Framework Directive 2000/60/EC.
To read our comprehensive coverage on the EU pesticide proposals - click here.