2015 Annual Mold Litigation Update: Important Decisions On Causation, Challenges To Medical Testing Reflect Ongoing Evidentiary Battle

Each year at this time we look back at the cases, studies and other developments which have impacted mold personal injury litigation over the last twelve months. After more than a decade of legal battles over which personal injuries can be attributed to mold exposure, and the type of evidence required to prove causation, Courts still struggle with these issues. This update highlights a key 2014 decision by New York’s Court of Appeals regarding the evidence necessary to prove causation, related decisions by other appellate courts which take contrary positions and a discussion of so-called “home brew” medical tests that are often the starting point for mold personal injury claims. Finally, we analyze how mold fits in with another litigation trend, the filing of so-called “habitability” lawsuits.

New York Court of Appeals Sets Higher Bar For Proving Causation - Cornell v. 360 West 51st Street Realty LLC.

On March 27, 2014, in a key appellate decision on causation, the New York Court of Appeals affirmed the dismissal of a tenant’s personal injury claims against her landlord. The Court’s opinion was based upon an in depth review of the scientific literature regarding mold exposure and disease in humans.

Plaintiff Brenda Cornell was a tenant in a New York City apartment for four years. She brought suit against her landlord and others involved with the management of the building in November 2004. Plaintiff’s complaint alleged that substandard conditions at the property resulted in excessive levels of dust, dirt, mold and debris in her first floor unit. Plaintiff claimed that this exposure resulted in dizziness, rashes, breathing problems and headaches, among other problems.

In 2008, defendant landlord moved for summary judgment of plaintiff’s mold personal injury claims, arguing that plaintiff was unable to prove that mold caused the type of injuries alleged (i.e., general causation) or that the mold allegedly present in her apartment caused her specific injuries (i.e., specific causation). Defendant requested a Frye hearing to determine whether plaintiff’s theory of causation “enjoyed general scientific acceptance.” The motion was granted and plaintiff’s claims were dismissed.

In bringing the motion in the trial court, defendant relied upon a clinical immunologist who assessed plaintiff’s physical and psychological problems and found that there was “no relationship between the medical problems experienced by the plaintiff and exposures to molds.” He cited medical literature that mold causes human disease, but only through specific mechanisms not present in the Cornell case (i.e., allergic reactions, direct fungal infection and ingestion of high levels of mycotoxins from spoiled or contaminated food where there is objective evidence of disease). The immunologist noted that molds are ubiquitous in the atmosphere and that the mold measured in the plaintiff’s apartment were at expected levels.

On appeal, the Appellate Division, First Department, reversed the lower court’s order, and reinstated the complaint against the landlord. The appellate division held that the lower court “erred in finding that [Cornell’s] proof was not strong enough to constitute a causal relationship, or that the methodologies used to evaluate her condition failed to meet the Frye standard." A further appeal to the New York Court of Appeals followed.

The New York Court of Appeals began its analysis with Frye v. U.S. (1923), which holds that expert testimony must be based on opinions that have general acceptance in the relevant scientific community. The Court noted that the defendant landlord set forth a prima facie case that the plaintiff could not prove general causation because plaintiff did not allege injury due to one of the diseases proven to be caused by mold. The State high court noted that plaintiff's reliance on government reports and public health initiatives and guidelines regarding mold in damp indoor environments were irrelevant since "standards promulgated by regulatory agencies as protective measures, are inadequate to demonstrate legal causation."

The Court also rejected the plaintiff’s claim of specific causation. It found that the plaintiff’s expert did not identify a specific disease-causing agent, other than to describe it vaguely as “an unusual mixture of atypical microbial contaminants, nor did he quantify her level of exposure to the unusual mixture.” The state high court also ruled that the record before it did not support the plaintiff expert’s “differential diagnosis.” The court stated that many of the medical conditions plaintiff attributed to mold exposure are common in the general population and could be the result of multiple alternative causes.

The decision concluded with a cautionary note, stating that its affirmation of the dismissal of the plaintiff’s mold personal injury claims “does not (and indeed cannot) stand for the proposition that a cause-and-effect relationship does not exist between exposure to indoor dampness and mold, and the kinds of injuries that Cornell alleged. Rather, Cornell simply did not demonstrate such a relationship on this record.”

This decision brings to a conclusion a battle regarding the standards to be applied and the quantum of evidence required to prove causation in mold cases which played out in an influential State court. We expect this opinion to be cited in other jurisdictions when defendants ask that plaintiffs prove both general and specific causation or face the dismissal of their mold personal injury claims.


Any internet search of terms related to mold injuries will bring up advertisements for medical labs offering blood testing or related diagnostic procedures, for a price. These tests claim to be capable of identifying “symptoms of mold exposure” or “mold sickness.” Notably, blood or tissue samples are drawn at home, by the patient or family members, and then shipped overnight to the lab. No physician referral (or involvement) is required. As a result, individual patients are left to evaluate both the validity of the tests and the meaning of the results.

Not surprisingly, the results of such testing often lead to individuals believing they have been injured and ultimately, to the assertion of claims and filing of lawsuits. The proliferation of such testing has garnered the attention of the scientific community and regulators. On April 18, 2014, the United States Centers for Disease Control and Prevention (CDC) published an alert. The agency had learned of a new test being used to diagnose Lyme disease, a tick-borne bacterial infection that can cause fatigue, joint pain and nervous-system problems. The test, like many others for the disease, had not been formally evaluated and approved by governmental regulators, and agency scientists worried that the method would churn out too many false positives. But because of a regulatory loophole, there was little the CDC could do except ask consumers to avoid the tests and urge people to seek out the few diagnostics that had been approved by the US Food and Drug Administration (FDA).

This same guidance applies to the numerous laboratory tests currently offered directly to consumers to diagnose mold related illnesses. In many instances, the labs offering the tests are certified. But the test methodologies are not. As the CDC noted: When evaluating testing options, providers and their patients might be confused by the distinction between Clinical Laboratory Improvement Amendments (CLIA) certification of laboratories and FDA clearance or approval of specific tests. CLIA certification of a laboratory indicates that the laboratory meets a set of basic quality standards. It is important to note, however, that the CLIA program does not address the clinical validity of a specific test (i.e., the accuracy with which the test identifies, measures, or predicts the presence or absence of a clinical condition in a patient). FDA clearance/approval of a test, on the other hand, provides assurance that the test itself has adequate analytical and clinical validation and is safe and effective.”

Government regulators are expected to take stronger action against these laboratories in the future. Until they do, anyone faced with assessing a mold personal injury claim should carefully scrutinize the results of medical testing supporting that claim. If the testing was done without physician supervision, or is not FDA approved, the results should be given little weight.

Court of Appeal of Louisiana: Circumstantial Evidence Sufficient To Prove Causation – Reddoch v. Parish of Plaquemines

Twenty five former employees of the Parish of Plaquemines sued for alleged personal injuries resulting from mold exposure while working in Parish emergency facilities. The evidence presented at trial consisted of the testimony of the plaintiffs, who viewed or smelled mold in the buildings, and a single report by an environmental consultant. That consultant, based upon two tape lift samples, confirmed the presence of seven types of fungi in the buildings. Plaintiffs alleged that as a result of the exposure, they suffered from headaches, asthma, allergies and sinus symptoms. No testimony from a physician on the issue of causation was presented at trial. The Court awarded a total of $280,000, with individual awards ranging from $5,000 to $25,000. The Parish appealed, arguing that the circumstantial evidence presented by plaintiffs was insufficient to prove causation. The Court of Appeal began its analysis by reviewing prior case law.

Plaintiffs in a mold personal injury case must establish causation on five different levels: (i) the presence of mold, (ii) the cause of the mold and the relationship of that cause to a specific defendant, (iii) actual exposure to the mold, (iv) the exposure was a dose sufficient to cause health effects (general causation), and (v) a sufficient causative link between the alleged health problems and the specific type of mold found (specific causation).

Watters v. Dep't of Soc. Servs., 08–0977, pp. 16–17 (La.App. 4 Cir. 6/17/09), 15 So.3d 1128, 1142–43.

Despite this seemingly high standard and the lack of medical experts to support plaintiff’s claims, the Court of Appeal held that the testimony of the plaintiffs, along with a single environmental report, was sufficient to prove causation.  The Court of Appeal noted that a determination of causation was a factual finding that should only be disturbed by an appellate court if “it is clearly wrong or manifestly erroneous.” The award by the trial court was affirmed.

Washington Court of Appeal Finds Testimony of Non-Physician Toxicologist Sufficient to Prove Causation – Bolson v. Williams

In a May 2014 opinion, the Washington Court of Appeal reversed a lower court decision, dismissing a plaintiff's claim against her employer for negligent cleanup of mold growth. Plaintiff Bonny Bolson was working as a tax accountant when a severe storm flooded her office. While attempting to repair the damage, the employer aggravated the mold growth, causing Ms. Bolson and other employees to allegedly experience coughing, headaches, and irritated eyes.

Plaintiff sought medical attention after developing flu-like symptoms. Ms. Bolson 's doctor discovered abnormal scarring on her lungs and diagnosed her with sarcoidosis, a condition characterized by abnormal collections of inflammatory cells. Ms. Bolson filed suit against her employer claiming their negligent cleanup and the resulting mold exposure caused her sarcoidosis. A lower court granted the employer's motion for summary judgment, finding a lack of evidence of medical causation. The Washington Court of Appeal reversed the lower court's order dismissing Ms. Bolson's claim.

In its decision, the Court explained the necessity of expert testimony in personal injury cases, stating that when an injury is not obvious to an ordinary person and involves "obscure medical factors" beyond an ordinary person's knowledge, expert testimony is required. Sarcoidosis is a disease many ordinary individuals are unfamiliar with, requiring expert testimony to establish a causal connection between exposure and the development of the disease.

The key finding by this Court was that the required expert testimony could be given by individuals who have expertise in the field relating to the injury, even if they lack a medical degree. In this case, a non-physician toxicologist and immunotoxicologist gave testimony finding that Ms. Bolson's sarcoidosis was more likely than not caused by her exposure to mold in the workplace and that although she had pre-existing conditions, the exposure exacerbated those conditions. This was sufficient, according to the Court of Appeal, to make the dismissal of the claim erroneous.

The difficulty with this decision is that it replaces a bright line rule - that expert testimony on medical causation must be provided by licensed physicians – with a vague standard. That standard now requires Courts in Washington to perform an analysis of “expertise” that may be beyond the technical competence of the bench and bar.


Mold claims are generally property based. Plaintiffs allege that their exposure is the result of inadequate construction or maintenance of a structure, causing water intrusion into the building envelope and the subsequent growth of fungi. The same defective construction or maintenance of a building resulting in mold can also lead to exposure to other potentially harmful substances, including lead paint, asbestos, dust mites, carbon monoxide and bacteria.

As a result, there have been a growing number of “habitability” lawsuits, generally by individuals or groups of tenants. These claims are made against landlords, management companies and the contractors they retain to repair and maintain rental properties. From the perspective of plaintiffs’ counsel, taking this approach has several advantages to filing lawsuits focused solely on mold.

When a case involves exposure to multiple substances, a single adverse finding on causation is not fatal. Defendants faced with claims involving multiple causes face a more difficult (and expensive) task, at both the pre-trial and trial phases of litigation. A jury may be persuaded that simply living with these problems is worthy of awarding damages or that the combination of these exposures has a synergistic effect. In many States, landlords are held to a higher standard of care, tenants face a lower burden of proof and may be entitled to statutory damages or an award for loss of use when making habitability claims.

In addressing this trend, property owners and their insurers and counsel need to adopt some of the same tactics we have recommended in responding to mold claims. A well documented maintenance and repair program is money better spent than defense costs once a claim makes it to Court. When issues do arise, use qualified consultants and contractors. The “gold standard” in environmental consulting in this context are individuals who are certified in Industrial Hygiene by the American Board of Industrial Hygiene. These individuals are designated by the acronym “CIH.” Once a lawsuit is filed, counsel who are familiar with all facets of these claims must be retained, e.g., construction and maintenance, toxic torts, personal injury and mold/water damage claims.

The difficulty that plaintiffs have faced in proving causation in mold personal injury lawsuits has resulted in a decrease in the number of actions focused solely on mold exposure. But the rise of habitability claims shows that when one door closes, another opens. For property owners, landlords and managers who feel a diminishing threat due to mold claims, habitability issues can create a more widespread problem.

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