Two neonicotinoids may restrict certain functions in growing human brains, according to a new study by the European Food Safety Authority (EFSA).
The study found that acetamiprid or imidacloprid may adversely affect the development of neurons and brain structures associated learning and memory.
Rat offspring exposed to the two chemicals weighed less, had reduced motor activity, smaller brains and decreased response to noise.
As a result, EFSA have said that guidance levels for acceptable exposure to the two chemicals should be lowered while further research is carried out.
The committee said that the acceptable operator exposure level (AOEL) for acetamiprid should be lowered to 0.025 mg/kg bw per day.
For imidacloprid, the current AOEL of 0.08mg/kg bw should be lowered to 0.06 mg/kg bw per day.
The study concluded that exposure to these two compounds may affect neuronal development and function, but said that further work was needed.
EFSA said that the available evidence had limitations but they believed the health concerns that have been raised are legitimate.
In April this year, the EU imposed a ban on three neonicotinoids, clothianidin, imidacloprid and thiametoxam, as a result of pressure to protect bee health.
The UK was one of the countries to vote against the ban, with chemical companies Bayer and Syngenta openly disputing it, although organisations such as the Soil Association welcomed it.
The ban came into force earlier this month.
