[10] A 2018 review by the European Food Safety Authority (EFSA) concluded that most uses of neonicotinoid pesticides such as Imidacloprid represent a risk to wild bees and honeybees.

[13] The pesticide has been banned for all outdoor use in the entire European Union since 2018, but has a partial approval in the United States and some other countries.

When used on trees, it can take 30–60 days to reach the top (depending on the size and height) and enter the leaves in high enough quantities to be effective.

[9] The estimated annual use of the compound in US agriculture is mapped by the US Geological Service and shows an increasing trend from its introduction in 1994 to 2014 when it reached 2,000,000 pounds (910,000 kg).

[19] In May 2019, the Environmental Protection Agency revoked approval for a number of products containing imidacloprid as part of a legal settlement, although some formulations continue to be available.

[22] On March 25, 1992, Miles, Inc. (later Bayer CropScience) applied for registration of imidacloprid for turfgrass and ornamentals in the United States.

[24] Imidacloprid is sold under several brand names, including Confidor (Bayer CropScience India),[25] Marathon (OHP, US).

[30][31] Based on laboratory rat studies, imidacloprid is rated as "moderately toxic" on an acute oral basis to mammals and low toxicity on a dermal basis by the World Health Organization and the United States Environmental Protection Agency (class II or III, requiring a "Warning" or "Caution" label).

The primary effects of longer term, lower-dose exposure to imidacloprid are on the liver, thyroid, and body weight (reduction).

Low- to mid-dose oral exposures have been associated with reproductive toxicity, developmental retardation and neurobehavioral deficits in rats and rabbits.

Exposed birds exhibited ataxia, wing drop, opisthotonos, immobility, hyperactivity, fluid-filled crops and intestines, and discolored livers.

[23][28] Imidacloprid is highly toxic to four bird species: Japanese quail, house sparrow, canary, and pigeon.

[23][28] According to the European Food Safety Authority, imidacloprid poses a potential high acute risk for both herbivorous and insectivorous birds.

[28] A 2014 observational study conducted in the Netherlands correlated declines in some bird populations with environmental imidacloprid residues, although it stopped short of concluding that the association was causal.

[51] The main routes of dissipation of imidacloprid in the environment are aqueous photolysis (half-life = 1–4 hours) and plant uptake.

When not exposed to light, imidacloprid breaks down slowly in water, and thus has the potential to persist in groundwater for extended periods.

The detections have generally occurred in areas with porous rocky or sandy soils with little organic matter, where the risk of leaching is high — and/or where the water table was close to the surface.

[16][28] According to standards set by the environmental ministry of Canada, if used correctly (at recommended rates, without irrigation, and when heavy rainfall is not predicted), imidacloprid does not characteristically leach into the deeper soil layers despite its high water solubility (Rouchaud et al. 1994; Tomlin 2000; Krohn and Hellpointner 2002).

[16][28] However, a 2012 water monitoring study by the state of California, performed by collecting agricultural runoff during the growing seasons of 2010 and 2011, found imidacloprid in 89% of samples, with levels ranging from 0.1 to 3.2 μg/L.

The authors concluded that "imidacloprid commonly moves offsite and contaminates surface waters at concentrations that could harm aquatic invertebrates".

Certain imidacloprid seed treatments were also temporarily banned in Italy, following preliminary monitoring studies that identified correlations between bee losses and the use of neonicotinoid pesticides.

[58] In January 2013, a European Food Safety Authority (EFSA) report concluded that neonicotinoids posed an unacceptably high risk to bees: "A high acute risk to honey bees was identified from exposure via dust drift for the seed treatment uses in maize, oilseed rape and cereals.

"[31] The EFSA also identified a number of gaps in the scientific evidence and were unable to finalize risk assessments for some uses authorized in the European Union (EU).

[59] In February 2018, the European Food Safety Authority published a further report concluding that neonicotinoids posed a serious danger to bees.

[60] On July 1, 2022, the Commonwealth of Massachusetts in the United States banned commercial sales of imidacloprid and other neonicotinoids – acetamiprid, clothianidin, dinotefuran, thiacloprid, and thiamethoxam – to the general public for all outdoor uses.