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Spot red flags in your supply chain

OSH indicators that signal modern slavery

Why OSH professionals should be alert to exploitation

Exploitation can be hidden within workplaces, supply chains and transport networks across the world. An estimated 27 million adults and children are trapped in forced labour, producing and delivering goods and services across a wide range of industries.

OSH professionals, procurement teams and organisations working with suppliers all have a role to play in identifying indicators of exploitation and taking appropriate action. This checklist highlights common warning signs that may be uncovered through routine observation, auditing and supplier due diligence.

What to look out for  

Many of the red flags which could indicate modern slavery, can be identified through robust OSH practice including observation and audit. The examples below are all issues which should be addressed through due diligence and ongoing supplier management, even if modern slavery concerns prove unfounded.

  • Workers may:  

     show fear or hesitation when asked whether they can stop unsafe tasks 
    report being punished, threatened, or dismissed for refusing dangerous work 
    continue hazardous tasks despite visible injury or exhaustion. 

    • Workers lack basic PPE (gloves, helmets, masks, harnesses) even in high‑risk environments 
    • PPE is withheld, locked away, or only provided to certain workers 
    • Training, information, instruction and awareness is not provided in a language workers understand, or workers say they were never trained.

  • Workers may:

    • show signs of exhaustion, microsleep, or physical collapse 
    • report excessive overtime, double shifts, night shifts, or seven‑day work weeks 
    • appear to be living on‑site or unable to leave the workplace. 
    • Disproportionate injuries among migrant workers, agency workers, or one nationality 
    • Repeated injuries linked to the same supervisor, task, or production line 
    • Workers hide injuries or avoid reporting them due to fear of retaliation.
    • Workers are denied medical treatment or told not to seek external care 
    • Injuries are treated informally on‑site to avoid documentation 
    • Workers report being charged for medical care or threatened with dismissal if injured.
    • Workers are not allowed to leave the site freely during breaks or after shifts 
    • Supervisors monitor or escort workers to toilets, canteens, or dormitories 
    • Workers appear anxious about being away from their workstations. 
    • Workers live in overcrowded, locked, or restricted dormitories 
    • Accommodation is directly tied to employment, with threats of eviction for complaints 
    • Fire safety, sanitation, and ventilation are visibly inadequate. 
    • No injury logs, training records, or risk assessments for high‑risk tasks 
    • Workers not listed on official rosters or payroll despite being on‑site 
    • Subcontractors unable to produce worker lists or OSH compliance documents.
    • Workers appear intimidated, avoid speaking, or look to supervisors before answering 
    • Workers show signs of physical abuse, untreated injuries, or chronic stress 
    • Workers express fear of losing wages, documents, or housing if they raise OSH concerns. 
    • Workers say they cannot raise OSH concerns safely 
    • No functioning safety committee, worker consultation routes, or migrant workers excluded from it 
    • Workers report being coached on what to say during inspections.

What to do about modern slavery concerns

Concerns should be handed over to the relevant authorities. Many countries have dedicated helplines for the reporting of forced labour.

OSH Management systems should include systematic procedures for identifying and controlling risks across supply chains, including modern slavery.

For more details, see the IOSH checklist for Supplier due diligence and quality assurance.