I dunno what paper you are quoting from. Here is a quote from the Buglife one...
"Roessink et al. (2013) examined acute and chronic toxicity of Imidacloprid to a wide range of aquatic insects and other crustaceans and found that mayflies (Ephemeroptera) and caddisflies (Trichoptera) were the most sensitive species in both acute and chronic tests, with LC50 and EC50 values in the range of 0.1 to 0.3 μg/L. At an environmental concentration of just 0.03 μg/L 10% of mayflies died."
So, a concentration of 0.03 μg Imidacloprid/L kills insects and the River Tame has an annual neonicotinoid conc of over 0.4 μg/L - nearly 15 times higher! That is not describing the corner of the tip of an iceberg.
"It is apparent from the data that the use of Imidacloprid as a veterinary medicine is a cause of serious concern. Pollution from flea treatments is the most likely source of chronic and harmful pollution on several urban rivers, and the insecticide was detected in one of the UK’s most pristine environments. The threat posed to aquatic life by high levels of Imidicloprid are clearly established, and immediate action to bring rivers back into a good chemical status is essential.
There is a bewildering array of toxins available to treat ectoparasites on pets in the UK, in addition to Imidacloprid another neonicotinoid Nitenpyram is used, as is the similar toxin Fipronil. Pyriproxyfen, Methoprene, Indoxacarb, Diazanon, Permethrin, Flumethrin, Fluralaner, Propoxur, Dicyclanil, Spinosad, Deltamethrin, Lotilaner, Afoxolaner, Sarolaner, Cyromazine and Cypermethrin are also used, only the latter is currently included under Water Framework Directive monitoring requirements. Some of these toxins are endocrine disrupters and may be further regulated by the EU. Having discovered that Imidacloprid pet treatments appear to be the cause of harmful pollution of waterbodies, it would be short sighted not to consider that other ectoparasite treatments may pose similar risks. The apparent pollution event on the River Tame indicates that monitoring of neonicotinoids has the potential to detect damaging insecticide pollution incidents in rivers; events that can be difficult to observe directly."
"The ecologically damaging levels of neonicotinoids detected in British freshwaters is a further example, were one needed, that current regulatory procedures are failing to provide sufficient protection to ecosystems. This problem has been recognised by Prof. Ian Boyd, the Defra Chief Scientist: “The current assumption underlying pesticide regulation — that chemicals that pass a battery of tests in the laboratory or in field trials are environmentally benign when they are used at industrial scales — is false.” “The United Kingdom has one of the most developed regulatory and monitoring systems for pesticides. Yet, it has no systematic monitoring of pesticide residues in the environment.” “Better regulation is needed to control how pesticides are used and affect the environment at a landscape scale.” (Milner and Boyd 2017).
The regulatory agencies should take the opportunities currently presented to address the shortcomings in insecticide regulation, as a model for a better future approach to pesticide regulation that would establish stronger regulatory tests prior to the initial approval of pesticide uses, and default post-approval monitoring of both environmental presence and impacts. It should not come as a surprise from the blue every time we realise that an insecticide is causing environmental harm, it can be predicted and managed. Finally, the process of insecticide approval, monitoring, risk management and review must be made vastly more independent, transparent and open."
"Recommendations
- Monitoring of these five neonicotinoids should be continued, regardless of their future Watch List status, and the number of sites and sample dates expanded. In particular more rivers should be included that are a) at risk of, or in probability are already, being impacted by arable insecticides and veterinary medicines, and b) representative of areas with greenhouses, extensive orchards, soft fruit production and commercial forestry.
- A comprehensive EU wide ban on the agricultural use of Imidacloprid, Clothianidin and Thiamethoxam should be introduced due to the unacceptable harm they are causing to the aquatic environment; this ban should include greenhouse uses. There is no obvious alternative way to reduce or mitigate their impact on aquatic life.
- Urgent action is required to reduce Imidacloprid pollution in water bodies and return them to a good chemical condition:
a) The use of Imidacloprid as an externally applied veterinary medicine should be suspended in the UK - this is the measure most likely to rapidly reduce chronic pollution levels.
b) A thorough review of the use of ectoparasite treatments, including a full risk assessment in relation to the aquatic environment, must be urgently undertaken. The report should make recommendations that address all risks of environmental harm. Currently ectoparasite medicines do not even come with a warning to pet owners indicating that they should keep treated animals out of streams, rivers, ponds and lakes.
c) If it becomes apparent that chronic pollution of aquatic habitats by ectoparasite treatments is originating via storm drains and/or waste‑water treatment works outflows then mitigation measures may not be feasible and permanent bans may be required.
4 The Environment Agency should develop a clear regulatory approach to responding to neonicotinoid pollution This should include:
a) Adopting and applying formal EQS standards based on a rational assessment of risk, considering the wealth of evidence relating to Imidacloprid and the likely comparable toxicity of the other neonicotinoids.
b) A clearly communicated approach to investigating and resolving neonicotinoid pollution events identified by monitoring.
5 The apparent pollution incident on the River Tame should be investigated and potential sources examined. Monitoring on this river should be stepped up to become at least fortnightly so that any future incidents can be detected.
6 Defra should establish an initiative to transform insecticide environmental risk management so as to ensure future generations have a better protected environment, in line with the Defra Chief Scientist’s recent call for improved “pesticidovigilance”. This should include:
a) Formal engagement between the Environment Agency, SEPA, NRW, Chemicals Regulation Directorate and Veterinary Medicines Directorate on a joint project.
b) The development of a new, independent, transparent and open approach that uses a more ecologically comprehensive evidence base in approving insecticide uses, monitoring environmental prevalence, researching environmental impacts, and reviewing post-approval use."
As I said - you either sit up and take notice, maybe look a bit further into it... Or you dismiss it and ignore it. Your choice. If car shampoo was the big issue, would the bug-lovers be getting their knickers in such a twist about insecticides?
The big clue is in the word 'insecticide', I reckon. Just sayin'...