## Facts

- The claimants were employees of Johnson Matthey plc exposed to platinum salts during their work in catalytic converter production.
- Exposure resulted in "sensitization," a physiological change rendering their immune systems highly reactive to platinum salts.
- Although the claimants had no immediate symptoms, sensitization restricted their ability to continue employment in environments containing platinum salts and increased the risk of future harm.
- The claimants argued that sensitization itself constituted actionable damage, as it impairmed their capacity to work with platinum salts.
- The central question was whether such asymptomatic physiological change, absent present symptoms or functional impairment, could amount to actionable damage in negligence.

## Issues

1. Whether asymptomatic "sensitization"—a physiological change without symptoms—constitutes actionable damage under English tort law.
2. Whether the inability to continue working in environments with platinum salts, stemming solely from sensitization, is sufficient harm for a negligence claim.
3. How the legal definition of damage distinguishes between risk, physiological change, and symptomatic disease in occupational exposure cases.

## Decision

- The UK Supreme Court unanimously held that sensitization constitutes actionable damage.
- The Court determined that the physiological alterations caused by sensitization were tangible and not merely a theoretical risk.
- It found that actionable damage does not require manifest symptoms or functional impairment if the individual's health or capacity to work is affected.
- The Court distinguished this case from earlier authority on pleural plaques, emphasizing the immediate practical impact of sensitization on work ability.
- The judgment clarified that the presence of physiological change with practical consequences satisfies the requirement of actionable damage in tort law.

## Legal Principles

- Actionable damage in negligence can include physiological changes that limit an individual’s ability to work or increase their susceptibility to future harm, even absent symptoms.
- The distinction between damage and mere risk remains central; genuine physiological change is actionable, while exposure to risk alone is not.
- The decision extends the range of compensable harm under tort law, encompassing asymptomatic injury where it produces real-world consequences.
- Employers may be liable for failure to protect against occupational hazards that cause asymptomatic but disabling physiological changes.

## Conclusion

The UK Supreme Court affirmed that physiological changes resulting in workplace incapacity, even without symptoms, constitute actionable damage in negligence. This decision broadens the legal understanding of harm in tort law, particularly regarding occupational exposures, and emphasizes the need for preventive protections in the workplace.


Dryden v Johnson Matthey plc [2018] UKSC 18