Most of the lead poisoning cases filed in the United States involve alleged emotional, psychological, or cognitive delays in young children. Despite the fact that there are countless scientific articles that discuss causes for these delays other than lead poisoning, far too often, plaintiffs rely on speculative or untested theories in an attempt to pass off “general causation” evidence as the required “specific causation” evidence.

The distinction between general and specific causation is critical to understand whether you are a lawyer, expert, or layperson trying to determine whether or not a substance actually caused injury to someone. For general causation, Courts look to see whether exposure to the substance at issue is capable of causing the type of ailments from which the plaintiff claims to suffer. However, proving general causation alone is not enough. A plaintiff must also show that exposure to the substance at issue caused the injuries to the specific plaintiff in the case.

On October 1, 2013, the United States Court of Appeals, Second Circuit had to opportunity to address the issue of general and specific causation in the Szewczuk v. Stellar (2003 WL 5433363) case. Plaintiffs alleged that their minor child suffered from neuropsychological problems as a result of lead paint present in defendant’s rental property. Plaintiffs’ expert, Dr. Theodore Lidsky, opined that neuropsychological impairments similar to the ones found in plaintiffs’ daughter were shown in the literature to be the result of childhood exposure to low levels of lead. While the Second Circuit agreed that it was possible that the child’s impairments could have been caused by lead poisoning (i.e., that general causation was met), they found that Dr. Lidsky cited to no scientific articles that discussed low level lead poisoning causing the actual impairments suffered by plaintiffs’ child (i.e. – the required specific causation element was not met). Several of the articles cited by Dr. Lidsky discussed injuries that were not found in plaintiffs’ child, while others only showed “loose associations” between low levels of lead in the blood and cognitive deficits.

The evidence presented by Dr. Lidsky was not sufficient to show specific causation in Szewczuk, and the Second Circuit upheld the lower court’s summary judgment ruling for defendants. The Szewczuk case is an important addition to rulings from across the country that have not permitted cases to proceed without valid specific causation evidence.