Those who work with pesticides are being reminded to make sure that the chemicals are properly stored properly and secured so that nobody can get at them.
A joint warning has been issued by the Health and Safety Executive (HSE) along with Natural England after a pest controller was found to be keeping the harmful substances in an unlocked shed.
The man was prosecuted and fined £1,000 for the pesticide offences and others are being warned that the consequences would be the same for them if they fail to comply by the rules.
Pesticides should be stored in a secured place in a fire resistant cabinet with signs on showing warning of their harmful nature.
Those found in the man's shed included aluminium phosphide, Rentokil Phostoxin and Luxan Talunex, which is no longer legal for use in the UK.
Dr Ed Blane, wildlife management senior specialist at Natural England, said: "Anyone who uses or stores these products must be properly trained. There is no excuse for storing such toxic pesticides in the manner found in this case. Products which are no longer approved should be correctly disposed of."
Some of the containers had been opened and resealed, making them even more dangerous and prone to releasing toxic gas had they come into contact with moisture.
Further to this the labels on several of the bottles were decayed making them unreadable, meaning anyone entering the shed would not know what they were.
Elaine Close, of the Chemicals Regulation Directorate at the HSE, said: "Pesticides are needed to control pests and weeds, but they can also be highly dangerous to people and the environment if used or stored incorrectly. That is why there are strict controls in place over their sale, storage and use."
The man also lives with his young son, who could have been seriously harmed if he had come into contact with the pesticides by accident.