Art rarely carries a public health warning even when the likes of Damien Hirst and Tracey Emin try to push the boundaries of taste.

However, the casualties have been mounting up at Tate Modern in London, where 15 people were hurt viewing Shibboleth 2007in the first four weeks after its opening.

Beginning as a crack, Shibbolethwidens and deepens as it snakes across the gallery’s Turbine Hall, until in some places it is large enough for a toddler to fall into. Staff have been detailed to monitor visitors wandering around the hall, but a Freedom of Information request by The Times has revealed that their efforts have not been entirely successful.

Four of the 15 accidents, some of which resulted in minor injuries, have been reported to the Health and Safety Executive. The museum has considered using Perspex glass to cover Shibboleth 2007, which opened on October 8 runs the full 167 metres (548 feet) of the cavernous hall.

Doris Salcedo, the Colombian artist behind the work, has said that her installation is intended to symbolise racial hatred and division in society.

Dennis Ahern, the Tate’s head of safety and security, told colleagues in an internal e-mail before the opening of the exhibit, that the primary risks associated with it were “obvious and quite simple” – the unwary could trip and fall “with the potential for significant leg injury”.

He added: “With Shibboleththis hazard differs from equitable ones in that physical protection measures which would normally be applied to a gap of this nature are not deemed appropriate due to its artistic nature.”

Nevertheless, while measures such as staffing, signage and lighting could reduce the likelihood of an accident occurring, Mr Ahern added that further options should be considered if it appeared that the existing measures were not enough.

He also advised that agreement should be obtained with the artist stating that the museum retained the right to apply the extra measures.

“Such options could include, but are not limited to, higher levels of control of entry, barrier or demarcation lines, Perspex bridging over certain sections or other physical interventions which may become required,” he added.

According to the same correspondence, Tate Modern is facing four other legal claims arising from other incidents, mostly related to the giant slides that last year occupied the hall.

Record numbers flocked to try out the five corkscrewing slides, the biggest of which was 55½ metres (182ft) long and had a drop of 27 metres.

In his e-mail, sent in July, Mr Ahern said that while the overall record of accidents and injuries at Tate Modern was low, pro rata to the visitor figures, the gallery reported eight accidents since February. They included one fatality, which was determined by a coroner to have been an accident.

In a risk assessment by Tate staff, the Shibboleth exhibit was given a score of two when it came to the likelihood of an accident, meaning that accidents were possible. But it also achieved a “severity score” of four, associated with severe accidents that could result in serious injuries, time in hospital and an HSE investigation.

A Tate spokesperson said that the museum took safety issues very seriously. There were warning signs in the gallery and leaflets were being handed out. She added that there were no plans to barrier off or cover the work.

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