Opinion ID: 1919140
Heading Depth: 1
Heading Rank: 17

Heading: Dose-Response Relationship

Text: A dose-response relationship is primarily a hallmark of toxicology. [79] If higher exposures to the agent increase the incidence of disease, the evidence strongly suggests a causal relationship. [80] For example, lung cancer risk increases in relation to the number of cigarettes smoked per day. [81] Based on this principle, some courts have held that a plaintiff cannot recover without showing (1) the level of exposure to an agent that is dangerous to human health and (2) the plaintiff's actual exposure to a level of the defendant's toxic substance that is known to cause harm. [82] In contrast, the Reference Manual states that a dose-response relationship presents strong but not essential evidence of a causal relationship. [83] Often, a physician will not have measures of the environmental exposure. An expert, however, can infer the exposure level from industrial hygiene studies or records and the patient's description of the work environment, duration of exposure, and his or her reactions. [84] Ellenbecker used this kind of data to estimate Bradley's exposure in his testimony. Relying on the Reference Manual, the Fourth Circuit has held that precise information about the exposure necessary to cause harm and the plaintiff's exact exposure level are not always necessary to demonstrate that a substance is toxic to humans given substantial exposure. [85] The court reasoned that in occupational settings, humans are rarely `exposed to chemicals in a manner that permits quantitative determination of adverse outcomes.' [86] Similarly, the Eighth Circuit has held that a plaintiff need not produce `a mathematically precise table equating levels of exposure with levels of harm' to show that she was exposed to a toxic level of a substance. [87] The court concluded that a plaintiff's claim does not fail simply because the medical literature had not yet conclusively shown the connection between the toxic substance and the plaintiff's condition. Thus, the court held that a plaintiff adduces sufficient evidence if a reasonable person could conclude that the plaintiff's exposure probably caused her injuries. [88] We have similarly upheld an expert's reliance on evidence of the plaintiff's substantial exposure to a known toxic substance. [89] So allowing semiquantitative or qualitative estimates of exposure from occupational studies and the plaintiff's testimony seems appropriate here. The evidence shows that the safe exposure levels to diesel exhaust are set low because it can unquestionably cause some diseases. [90]