The Tylenol Tampering Incident When seven persons from surburban Chicago died after taking Extra Strength Tylenol capsules that had been maliciously adulterated with cyanide, the random and wanton nature of the killings caused extensive publicity. Although general information about the forensic work that accompanied the intensive investigation was released to the media, detailed accounts of certain aspects of the analyses were withheld. The Food and Drug Administration (FDA) has dealt with nationwide poisoning crises before (with mushrooms and salmon, for example). This time, however, the problem was not a processing or manufacturing mistake but murder. This ANALYTICAL APPROACH article describes the series of events that led to the involvement of FDA's Elemental Analysis Research Center (EARC) in the world of homicide investigation. In the hours immediately following the initial discovery that capsules tainted with lethal amounts of potassium cyanide were responsible for three deaths in the Chicago area, federal, state, and local authorities were faced with a crisis of unknown magnitude. McNeil Consumer Products Company, a subsidiary of Johnson & Johnson and manufacturer of Extra Strength Tylenol, quickly recalled Tylenol capsules marketed in the Chicago area. Within a matter of days, FDA field offices had collected and inspected more than one million Tylenol capsules from across the nation (1). An additional bottle of adulterated
Tylenol containing 14 capsules packed with lethal amounts of cyanide was recovered from a suburban Chicago drugstore by FDA investigators. No additional cyanide-laced capsules were found outside the Chicago area. A massive campaign was launched urging Chicagoans to avoid taking Tylenol capsules. Consumers were asked to return recently purchased bottles to local stores or police departments, and subsequently two more bottles containing poisoned capsules were retrieved. Fast action by the authorities undoubtedly averted additional fatalities. Initially, the possibility that tampering could have occurred during the manufacturing or shipping process was a major concern of the FDA. Although it is not used in the production of Tylenol, KCN is used as a testing reagent in laboratories at the manufacturing plants, and a quantity of KCN also was found in a Chicago warehouse where the implicated capsules had been stored. The fact that the tainted capsules were manufactured at two different locations—in Pennsylvania and Texas—lent support to the theory that the tampering probably occurred after the product reached the retail level; however, corroborating evidence was sought. Forensic scientists have often used the total elemental composition of a material, such as paint or glass, to act as a "fingerprint" for a particular batch of that material. The identity and relative amounts of various ele-
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mental constituents in a suspect sample form a distinct pattern that can be used for comparison with other samples, much like actual fingerprints. In this instance, the identifying pattern was developed by determination of trace element contaminants in KCN (which turned out to be a relatively
KCN from an adulterated
capsule
This article not subject to U.S. Copyright Published 1984 American Chemical Society
The Analytical Approach Karen A. Wolnik Fred L. Fricke Evelyn Bonnin Cynthia M. Gaston R. Duane Satzger Elemental Analysis Research Center U.S. Food and Drug Administration 1141 Central Parkway Cincinnati, Ohio 45202
Tracing the Source pure reagent) using inductively coupled plasma-atomic emission spectrometry (ICP-AES). ICP-AES Analysis Cyanide samples were analyzed using a Jarrell-Ash Model 1160 ICP/ polychromator with 34-element capa-
Contents of a normal capsule
bility and automatic background correction. The instrument was equipped with an adjustable cross-flow nebulizer and operated at a power of 1 kW; argon coolant flow of 18 L/min; sample argon flow of 0.65 L/min; sample uptake rate of 1.5 mL/min (pumped); viewing height of 15 mm above the load coil; and exposure time of 8 s on line and 4 s on background. In most cases samples ranging from 250 mg to 1 g in size were diluted with distilled deionized water (DDW, metered resistance 18 megohm/cm) to a concentration equivalent to 5 mg KCN/mL. The amount of KCN in the analyte solution was limited by the fact that cross-flow nebulizers tend to be unstable or can clog when solutions with salt content greater than 1% are nebulized (2). Introducing high levels of KCN into the ICP causes some signal suppression; therefore, quantification of the trace element constituents in KCN was performed by the method of standard additions with the exception of Na. Sodium and potassium were determined after further dilution (1:25 with DDW) vs. calibration curves. Analysis of various samples of reagent-grade cyanide for 34 elements by this procedure revealed measurable levels of K, Na, Ca, Fe, Mg, B, Si, and, in some cases, Ba, Sr, and Zn. The elements boron and silicon proved to be unreliable chemical indicators because of background stemming from the borosilicate glass volumetric ware and quartz ICP torch. Since the identity of
the contaminants in KCN varied little from sample to sample, it was the relative amounts of these contaminants that led to a fingerprint. The I C P AES technique is particularly useful in this case because it enables accurate, precise, quantitative multielement determination of these elements at the ppb level in solution. Results The seven tragic deaths, including three members of one family and a 12-year-old girl, had been caused by cyanide-laced capsules taken from five different bottles of Tylenol. Each bottle contained several tainted capsules packed with 500-800 mg KCN, but by the time the EARC became involved in the case, only a few poisoned capsules (or portions thereof) were available for analysis following the urgent and exhaustive forensic work done by the local medical examiner and other crime labs. The recovery by FDA of an intact sixth bottle was fortunate because it provided the investigative team with a reserve supply of adulterated capsules that presumably were linked to the murders. Determination of potassium levels in the cyanide material taken from
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Figure 1. Analysis of KCN reagent samples and KCN from contaminated capsules
Figure 2. Analysis of KCN samples from cyanide manufacturers and KCN from contaminated capsules 468 A · ANALYTICAL CHEMISTRY, VOL. 56, NO. 3, MARCH 1984
adulterated capsules in the sixth bottle confirmed that the chemical was essentially "pure" KCN. Figure 1 shows a comparison between the range of trace element results for samples of KCN obtained from the sixth bottle and trace element levels in several other important samples of KCN reagent. These samples were collected from the two plants responsible for the manufacture of the five bottles of Extra Strength Tylenol purchased by the victims and from the Chicago warehouse where the popular pain reliever had been stored. The results of these initial analyses indicated that the trace element levels in KCN vary from distributor to distributor and lot to lot. Significantly, KCN from two different bottles with the same lot number, one used by Quality Control (QC) and the other by Consumer Products Control (CPC) at the manufacturing plant, had very similar trace element levels in spite of being handled by different laboratory personnel. These data all served to verify the premise that trace element levels measured by the ICP-AES procedure are characteristic of the KCN from any particular bottle and therefore constitute a fingerprint of sorts. This identifier could be used to demonstrate similarities or differences between suspect cyanide samples. In each case shown in Figure 1, trace element patterns differ from the capsule KCN fingerprint, and therefore these reagents were not the source of KCN used in the Tylenol incident. This provided further evidence that tampering had in fact occurred at the retail level. There are only three companies worldwide that produce potassium cyanide: Degussa in West Germany, I.C.I, in England, and Du Pont in the U.S. Results of analyses of the raw material from each firm are shown in Figure 2. Most likely, the cyanide used to poison the capsules in the sixth bottle was made by Du Pont, in view of the presence of Ba in the sample from Germany, the high levels of Na in both foreign samples, and the absence of these indicators in the capsule cyanide. More than 2 million lbs of KCN have been produced by Du Pont in the past five years, and most KCN marketed in the U.S. is manufactured by that firm. Reagent-grade KCN is repacked from Du Pont raw material by six or eight major distributors. Potassium cyanide is surprisingly available, with more than 65 legitimate users in Chicago alone, ranging from hospital laboratories and universities to steel mills. Once authorities were convinced
Figure 3. Analysis of KCN in contaminated capsules
that the ICP-AES elemental fingerprint technique had merit, the remaining capsule contents from two homicides were brought to the EARC for analysis. Results, shown in Figure 3, indicated that the KCN in both cases originated from the same source. Comparison with the identifying pattern for the KCN from the sixth bottle was not as conclusive, however, particularly with respect to sodium. The fingerprint for the capsule contents could have been altered slightly when the capsules were emptied since the original analysts took no special precautions to avoid elemental contamination because they had no way of anticipating its potential significance. Table I lists trace element levels for KCN removed from intact Extra Strength Tylenol capsules by the EARC. Cyanide samples from the sixth, seventh, and eighth bottles and from the adulterated bottle of Tylenol implicated in the death of the 12-yearold girl were undoubtedly derived from the same source. The variability (% RSD) among samples taken from different capsules is only slightly higher than for repeated analyses of a single bottle of KCN reagent. Remember_ that the potentially lethal seventh
and eighth bottles had been returned by their purchasers in the recall. As suspects came under the scrutiny of local police, the Federal Bureau of Investigation, or state law enforcement agencies, samples of cyanide ac-
cessible to suspect individuals were flown at all hours of the day and night to the EARC for analysis. This chemical chase is part of a continuing effort to find some clue to the identity of the killer by finding KCN with a matching trace element fingerprint. Nearly 300 samples have been analyzed in this search for the source of the deadly cyanide used in the Chicago murders. The publicity surrounding the Tylenol case spawned an epidemic of copycat tampering incidents around the nation. If there was any hint that cyanide was involved, samples were rushed to the EARC to check for a possible link to the Chicago murders. From the perspective of the FDA, it was also important to rule out the possibility that any cyanide found in the manufacturing plant was an accidental or intentional source of poison in the product. The technique of trace element fingerprinting using ICP-AES was applied in numerous copycat tamperings that involved other toxic or harmful chemicals such as HC1 (in eyedrops), NaOH (in capsules), HgCl 2 (in capsules), NaF (in artificial sweetener), and so on. Results often were very useful in helping the FDA to evaluate the scope of the problem and in assisting police to focus on a particular suspect. Sometimes, however, the fingerprint results were too ambiguous to provide decisive evidence. Mercuric chloride is one example in which the reagent is so pure that even when solutions as concentrated as 2% HgCl2 were introduced into the ICP, traces of Fe and
Table 1. Elemental Analysis of KCN in Tylenol Capsules Ca (/*g/g)
Fe (f*g/g)
Mg (/ig/g)
Na
