The phrase "alleged impact" is correct and usable in written English.
It can be used when discussing a claim or assertion about the effects or consequences of something that has not been definitively proven.
Example: "The researchers examined the alleged impact of the new policy on employee productivity."
Alternatives: "purported effect" or "claimed influence".
Because of hedge funds' alleged impact on the markets in the 1969 bear market, the SEC started to consider ways to bring them under its regulatory authority.
Examples range from fake news spreading via Facebook (and its alleged impact on elections) to surreptitious tracking of shoppers in malls based on signals emanating from smartphones.
The results of the report, which echo similar studies largely debunking the alleged impact of windfarms on health and house prices, were welcomed by WWF Scotland director Lang Banks.
The laws have stirred controversy in Sydney because of the alleged impact on nightclubs and nightlife in the city, and many believe they were unnecessary because the assaults were declining.
The weekly right-wing rallies are organised by a group called Pegida, or the "Patriotic Europeans against the Islamization of the West" and they often accuse mainstream media of lying about immigration issues relating to the alleged impact Islam has on non-Muslim majority countries.
Brexit campaigners have made less noise than I might have expected about the alleged impact of the "secret" (ie staged in private) negotiations between the EU and US for a Trans-Atlantic Trade and Investment Partnership, the inter-regional freer trade talks known as TTIP or "T-Tip".
Since 2007, many media stories have appeared about alleged negative impacts of biofuels, notably the price of food going up or land-grab by plantation developers.
As for alleged negative impacts, a study for a federal panel on gambling found that casinos do not increase crime or bankruptcy and "gambling appears to have net economic benefits for economically depressed communities".
Arguments alleging negative impact on "unit cohesion" were also used against integrating African-Americans.
Due to alleged higher anthropogenic impact, cropland samples could presumably be slightly higher in concentration than those deriving from grassland.
Mark Zaid, a national security lawyer, said: "This is called potentially tainting jury pool and could impact alleged perpetrator's ability to secure fair trial".
