Strict toilet break rules and inadequate facilities are causing discomfort and humiliation for some workers, a labour organisation says.
The Labour Research Department said the transport sector was particularly bad, with bus drivers struggling to find time to use the toilet between routes.
Few office workers were inconvenienced although some call centres did penalise staff for time spent on the loo.
The LRD said all workers needed proper access to clean facilities.
Other industries highlighted in the report for being badly affected were mining, construction and quarrying.
People with health problems, including irritable bowel syndrome, experienced particular difficulties.
Some of the more extreme practices, according to the report, were a call centre team which handed workers going on toilet breaks a wooden spoon. Until the spoon was returned, no-one else could use the toilet.
In some meat industry plants, workers were banned from leaving the production line to use the toilet for shifts of up to four hours, researchers found.
And caretakers at one housing association only had access to a bucket in a washroom area.
Researcher Dave Statham said: "For most workers, toilet breaks are not an issue: they go when they need to and that's that.
"But for some the situation is not so simple and the consequences can be unpleasant, unhealthy and humiliating.
"Employers in all industries need to realise that staff need proper access to clean facilities and to be able to go when they need to without harassment or loss of pay."
The Labour Research Department is an independent trade union and labour organisation.