A syringe and a stethoscope are arranged on top of an information paper about Huntington's disease
Plaintiff unable to prove that exposure to natural gas leads to early onset of Huntington’s disease

Virtually all lawsuits that arise from gas leaks are based on the ignition of the gas — a fire or explosion that injures people or damages property. But from time to time, a plaintiff will claim that mere exposure to the leaking gas has caused personal injury, even when there is no ignition of the gas. These kinds of cases often arise from the leakage of pure odorant. But in a recent case, a plaintiff claimed that exposure to leaking natural gas triggered the onset of her Huntington’s disease. The case is Allen v. Consolidated Edison of New York.

Red Tags

In 2009, Tanita Allen leased an apartment in New York City. Over the winter of 2010-2011, she began to smell gas in the apartment and had problems with her gas cookstove. At one point, her carbon monoxide detector sounded. In February 2011, she reported these problems to her natural gas supplier, Consolidated Edison (Con Ed).

A Con Ed service technician inspected Allen’s apartment, and he also smelled gas. He therefore shut off the gas supply at the meter control valve and placed an “A classification” red tag on the gas meter, signifying an immediate hazard. Normally, it would be up to the property owner to hire a professional to find and repair the leak. It is not clear from the court opinion whether that was done in this case.


However, in July 2011, the gas had apparently been turned back on to the apartment, and another Con Ed service technician responded to a gas odor call. This technician also smelled gas and had a positive gas reading near Allen’s stove using his hand-held gas detector. He determined that the meter control valve was leaking. A second red tag was placed on the meter, and this time the line to the apartment was plugged. There was never a fire or explosion.

Early Onset

Some time after these events, Allen began to manifest the symptoms of Huntington’s disease, a neurodegenerative disease that progressively affects body function and movement, mental function and speech. While this disease is generally believed to be inherited based on genetic characteristics, Allen concluded that its onset must have been triggered by her exposure to gas fumes. She sued Con Ed, her landlord and others.

Allen presented expert testimony from a neurologist and a toxicologist, who testified that exposure to leaking natural gas can trigger the early onset of Huntington’s disease, and that this in fact happened to Allen. The defendants responded with their own expert neurologist and toxicologist who disagreed, and the defendants filed a motion to preclude the testimony of the plaintiff’s experts on the grounds that it had no reliable scientific basis. They added a motion for summary judgment, seeking dismissal of Allen’s claims.

Venezuelan Study

In addressing these motions, the trial court first noted that natural gas itself is not toxic; it only becomes toxic in the highly unusual circumstance when it displaces oxygen in a room. (The same is true for propane.) Allen’s experts had pointed to a Venezuelan study that concluded that environmental factors, including pollutants from the oil industry, could possibly contribute to early onset of Huntington’s disease.

However, the court found that this study “did not identify natural gas, methane or carbon monoxide as the cause of triggering early onset of Huntington’s disease.” In fact, both sides agreed that there are no scientific studies linking natural gas to early onset of Huntington’s disease. And there was no evidence that a possible linkage had ever even been discussed in any scientific or medical literature, or that the subject had been raised in any scientific or medical meeting.

In addition, Allen’s experts admitted that, even without exposure to leaking natural gas, she had a 2% chance of manifesting Huntington’s disease at the age she did.

Given these facts, the court was highly critical of the approach taken by Allen’s experts, stating that they had engaged in “backward reasoning” — in other words, they worked backward from Allen’s symptoms to the cause of her disease.

Symptoms Before Exposure

But perhaps more importantly, Allen manifested symptoms of the disease in early 2010, which was before her exposure to the leaking gas. The plaintiff’s experts admitted, “The onset of Huntington’s disease cannot be triggered twice.” The court stated:

“Therefore, if plaintiff’s Huntington’s disease was triggered in early 2010 or the summer of 2010, it was not triggered by the gas leak in her apartment.”

The court summarized its conclusions for ruling in favor of the defendants:

“There are no studies linking exposure to natural gas triggering the early onset of Huntington’s disease, nor is there evidence of any discussion in the relevant scientific community of such a possibility. Moreover, under the facts of this action, plaintiff manifested symptoms of Huntington’s disease prior to her exposure to natural gas.”


The court stated that “plaintiff’s experts are precluded from testifying that expression of plaintiff’s Huntington’s disease was triggered by her exposure to natural gas.” It entered judgment in favor of the defendants, and Allen appealed.

The appellate court affirmed the decision in favor of the defendants. It emphasized that there simply are no scientific studies or evidence supporting a connection between exposure to natural gas and the onset of Huntington’s disease. It added that the plaintiff’s experts used an “inverse approach” (or backward reasoning) to causation, which has been “squarely rejected” by New York courts.

The Allen case is unusual. In over 35 years of representing propane and natural gas distributors, I have never seen or heard of such a claim before this one. The court here properly rejected the claim, and its decision provides a good blueprint for the defense in the event such a claim is asserted in the future. And although this case involves natural gas, the same theory could have been advanced for exposure to leaking propane. If such a claim is ever asserted, the Allen decision provides an equally good defense blueprint for the propane distributor as well.

David Schlee is of counsel to The McCarthy Law Firm P.C. He may be reached at david@mokpclaw.com.


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