职业暴露和环境污染引起疾病的因果关系的判断:总体判断和个体判断

Causal Relationships between Occupational and Environmental Exposures and Injury:General Causation and Specific Causation

Demonstration of a causal relationship between chemical exposure and injury in litigation of toxic tort cases is a key to winning the case in Court. To evaluate whether a case has merit,two levels of causations,general causation and specific causation,are considered.“General causation” refers to the question,does exposure to the toxicant cause the type of injury? For example,does aluminum welding fume cause lung cancer? Bradford Hill’s nine criteria are used to analyze “general causation.”These criteria include strength of association,consistency,specificity,temporality,biological gradient,plausibility,coherence,experiment,and analogy.“Specific causation” refers to the question,did the Plaintiff’s exposure to the toxicant cause the injury in this individual.For example,was Mr.Smith’s lung cancer caused by his occupational exposure to aluminum welding fume? In court,the Judge and jury are asked to make a decision about specific causation,and award or deny damages accordingly. The expert witnesses testify as advisor to the court.As health consultants,we ask five questions to evaluate specific causation: 1.Was the individual exposed to a toxicant,and if so,what was the dose(route,concentration,duration,and frequency)? 2.What is known about the toxicity of that chemical?(e.g.,What specific adverse effects have been associated with exposures to that toxicant? How long does it take for symptoms to develop? What dose is required? The analyzing process of general causation is included in our question 2.) 3.Did the symptoms claimed by this individual appear in a manner and time sequence that is consistent with what is known about the toxicity of the chemical? 4.When exposure to the chemical ceased,did the symptoms get better or disappear in a manner and time sequence that is consistent with the known toxicology? 5.What other conditions or factors might have caused this symptom,and are they relevant to this case? By reviewing the available information relative to these five questions,the testifying expert helps the judge and jury decide whether the plaintiff’s injury was,or was not caused by his exposure to a chemical toxicant.