A warning to shoppers has been fired off this week after a Whitechapel market trader was caught selling henna products with a potentially lethal toxic substance.

East London Advertiser: Henna cones which Tower Hamlets trading standards officials found contained the banned Phenol substance that can prove fatal. Picture: LBTHHenna cones which Tower Hamlets trading standards officials found contained the banned Phenol substance that can prove fatal. Picture: LBTH (Image: LBTH)

The stallholder admitted four summonses at Thames Magistrates Court before Christmas when he was ordered by magistrates to pay more than £3,500 in fines and costs.

Details have since emerged of the Tower Hamlets trading standards operation in the market when the trader was found selling products containing banned substances.

"Our officers won't hesitate to take action," Mayor John Biggs warned. "The majority of traders are honest retailers, but there will always be individuals who ignore the law."

The henna products had no safety label which is required by law.

East London Advertiser: Mayor John Biggs... warning of Phenol substance found in henna products being sold in Whitechapel Market. Picture: Mike BrookeMayor John Biggs... warning of Phenol substance found in henna products being sold in Whitechapel Market. Picture: Mike Brooke (Image: Mike Brooke)

So trading standards officers seized 42 cones, 11 nail hennas and five other items, which were sent for testing.

The cones were found to contain phenol, a toxic substance banned under the 2013 Cosmetic Products regulations. Phenol can cause irritation swelling and burns, the council warns. It can also be fatal in extreme cases if ingested.