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Neuropsychological effects of formaldehyde use.

Formaldehyde is an efficient cellular preservative useful in a variety of industrial settings, most notably, in its use as an embalming fluid. It is also a well known neurotoxin which has recently become popular among substance abusers for its rapid onset euphoria, availability, and low cost; it is known on the street as "wet" or "fry." However, the neuropsychological and cognitive effects of formaldehyde are not well known. There has been considerable research into the physiological effects of formaldehyde in industrial setting, but limited research into the neuropsychological effects.


Formaldehyde is a component in the manufacture of plastics, foam insulation, and resins used to make construction materials, paper, carpets, textiles, paint, and furniture (Wilbur et al. 1999). The best known use of formaldehyde is as an embalming fluid. Embalming fluid is a compound of formaldehyde, methanol, ethanol (ethyl alcohol), and other solvents (NDIC 2004; Wilbur et al. 1999).

Side Effects of Exposure

Inhalation of industrial formaldehyde has been shown to cause exposed individuals to have a decrease in performance, lack of concentration, loss of memory, disturbed sleep, impaired balance, variations in mood, and irritability (Wilbur et al. 1999). Oral exposure has been found to cause lethargy, seizure, and loss of consciousness (Wilbur et al. 1999). In occupational exposure, the neurotoxicity of formaldehyde is low. The nervous system does not appear to be a major target for formaldehyde toxicity; however, some vague neurological symptoms occur after inhalation; these include headaches, fatigue, and increased reaction time (Wilbur et al. 1999).


Formaldehyde is a known toxin that has become popular among drug users; in its various forms, it is known on the street as "wet" or "fry." Formaldehyde embalming fluid is legal to purchase and possess and is easily accessible; individuals can obtain it through retail sale and staff of morgues, hospitals, and funeral homes (Klein & Kramer 2004). From these resources, formaldehyde is available to those who want to use or sell it for its euphoric and hallucinogenic effects.

Fry is a generic term referring to marijuana cigarettes, marijuana-laced cigars, or tobacco cigarettes that are soaked in embalming fluid and dried (Elwood 1998; NDIC 2004). This embalming fluid is often laced with PCP (Elwood 1998; Holland et al. 1998). The term fry will be used in the majority of this article in reference to this specific use of formaldehyde. The symptoms of fry intoxication are nearly identical to those seen following PCP use. Both PCP and THC (in marijuana) have reinforcing effects, and the formaldehyde embalming fluid is thought to enhance absorption by slowing the rate at which marijuana burns; it is unknown if the substances interact or have any kind of synergistic effects (Modesto-Lowe & Petry 2001). Most drug users do not know that fry (formaldehyde embalming fluid) bought on the street contains PCP (Connecticut Clearinghouse 2002). It is impossible to quantify the amount of embalming fluid that is smoked with or without PCP since it often goes undocumented by poison control centers and clinicians (Holland et al. 1998).

Side Effects

The primary side effect of smoking fry (PCP-laced formaldehyde-soaked marijuana or tobacco cigarettes) is toxic psychosis. Other effects include hallucinations, delusions, panic, paranoia, increased sexual arousal, and loss of consciousness (Klein & Kramer 2004). Side effects associated with inhalation of formaldehyde embalming fluid are disorganized thoughts, decreased attention span, psychomotor agitation, and up-regulation of the sympathetic nervous system (Klein & Kramer 2004).

Physiological Effects

Exposure to embalming fluid alone can result in bronchitis, body tissue destruction, brain damage, lung damage, impaired coordination, and inflammation and sores in the throat, nose, and esophagus (NDIC 2004; Hammack 1998). The use of PCP alone also has physiological effects, which can include impaired motor coordination, seizures, and respiratory arrest (Hammack 1998).

Psychological Effects

PCP is a dissociative anesthetic that can cause dependence, hallucinations, depression, extreme anxiety, disorientation, paranoia, aggressive behavior, and violence (Hammack 1998). Reported effects of fry include feelings of panic, paranoia, and disorientation, all of which mirror those effects of PCP alone (Hammack 1998), as well as memory impairment (Holland 1998).

Duration of Effects

The various effects of smoking fry have been reported to last from hours to months. Although the effects are not well known, there are a number of effects that are identified in many cases of fry use.

Short-term effects. Reported short-term effects include impaired vision, headache, and increased forgetfulness (NDIC 2004). Research has not clearly found any other short-term effects that are a result of fry alone.

Long-term effects. Unfortunately, the long-term effects of fry are not as well understood as its individual components. Long-term use of PCP can lead to memory loss, difficulty with speech or thought, depression, and weight loss; these effects have been found to persist up to a year after using PCP (NDIC 2004). Embalming fluid and marijuana are both carcinogenic, leading to an increased risk for cancer. There is also evidence that fry may cause dysmnesia (Hawkins, Schwartz-Thompson & Kahane 1994).

Unfortunately, most of the information about the effects of fry use come from common sources that are based on self-reports or case studies. It is evident that much empirical research is needed to find the effects of smoking fry. This study is an attempt to further the research in this area using a control group in comparison to a group of individuals who have done fry. Due to the neurological effects of formaldehyde exposure, in both occupational and illegal uses, this study focuses on the effects of fry use (smoking PCP-laced formaldehyde-soaked marijuana or tobacco cigarettes) specific to intellectual ability and cognitive intactness. Researchers used the Shipley Institute of Living Scale (SILS) to measure intellectual impairment in individuals who have used fry (experimental group) in comparison to a control group. The SILS is based on clinical and research findings suggesting that intellectual impairment differentially affects various cognitive abilities--vocabulary has proven relatively resistant to change, whereas abstract thinking has been shown to be more susceptible to cognitive deterioration (Shipley 1939). The hypothesis of this study is that the experimental group (fry users) will have lower scores on the SILS than the control group. Since there is no prior research in this area, it is uncertain whether the experimental group will have lower scores across all measures of the SILS.



Experimental group. The experimental group is comprised of five individuals with a mean age of 28.6 years and a mean education level of 10.4 years. All individuals in this group reported having done "fry" or "wet" and came from various agencies in Southwest Louisiana from September to November of 2005. These agencies requested neuropsychological evaluations based on the self-reports of this specific drug use.

Control group. The control group began with fifteen males from the Lake Charles, Louisiana community with a mean age of 26.8 years and a mean education level of 12.2 years. The researchers picked five of the fifteen participants using a table of random numbers. Counseling Services made their office available to conduct the assessments and offered to contact individuals from local blue-collar jobs. The purpose of this selection was to obtain a control group of similar education level, occupational level, and age as the experimental group. This method is one that was suggested to get an accurate control group to use with such a specific type of experimental group.


The researchers used the Shipley Institute of Living Scale (SILS) to measure each participant's level of cognitive and intellectual ability. The Shipley Institute of Living Scale (SILS) is a well-established test measuring intellectual ability and cognitive intactness and enjoys broad acceptance among the clinical field in assessing cognitive and intellectual impairment. The scale is composed of two brief subtests: (1) a 40-item vocabulary test that requires the respondent to choose which of four listed words "means the same or nearly the same" as a specific target word; and (2) a 20item abstract thinking test, which requires the respondent to fill in numbers and letters that logically complete a given sequence.


The participants read and signed a consent form given to them by the researcher. Upon signing, the participants then began by filling out a short demographic sheet including age, gender, education level, and current drug use. The researcher then administered the Shipley Institute of Living Scale. Participants completed testing in one session. The SILS took approximately 22 minutes to administer (10 minutes for each subtest and two minutes for instructions). After participants completed the SILS, the researcher asked if they had any questions. A licensed psychologist supervised all testing, and administration of the SILS was done according to the respective manual (Shipley 1939).


The SILS was scored utilizing a computer program supplied by Dr. Charles Robinson. This program provided a t-score for each subtest (vocabulary and abstract) and a total SILS t-score.

Data Analysis

This study was a quasi experiment requiring an independentsamples t-test to compare mean SILS t-scores of the control group to mean SILS t-scores of the experimental group.


In past research, education level of participants has been found to be related to the abstract t-scores of the SILS. Therefore, an independent-samples t-test was done to compare education levels of the experimental and control group. There were no significant differences found among mean education levels; hence, this would rule out any differences found on the SILS abstract test being due to educational level, leaving only formaldehyde use as an independent variable.

To test the hypothesis, an independent-samples t-test was conducted to indicate any significant differences among the SILS mean t-scores of the experimental and control group. There were significant differences found on all measures of the Shipley Institute of Living Scale. In the SILS vocabulary subtest, the mean t-score for the experimental group (M = 29.2, SD = 9.55) was significantly lower than the mean t-score for the control group (M = 51.2, SD = 7.40), t(8) = -4.073, p = .004. This was surprising since the SILS manual clearly states that vocabulary typically remains stable and is resistant to change (while abstract thinking is often more susceptible to cognitive deterioration). On the SILS abstraction subtest, the experimental group t-score means (M = 35.4, SD = 2.41) were lower than those of the control group (M = 54.4, SD = 7.80), t(4.756) = -5.206, p = .004, indicating that the experimental group has significantly lower capabilities of abstract thinking. The most significant difference was found in the total t-scores between the groups. The mean total SILS t-score of the experimental group (M = 28.8, SD = 6.9) was lower than that of the control group (M = 53.4, SD = 53.4), t(8)=-5.085, p = .001. Thus, the experimental group had lower cognitive abilities in general.


The results of this study support the hypothesis that the experimental group (fry users) had lower scores on the SILS than the control group. The implications of these findings are that using fry has powerful consequences, leading to cognitive impairments in both vocabulary and abstract thinking. In most circumstances, vocabulary typically remains stable and is resistant to change while abstract thinking is often more susceptible to cognitive deterioration (Shipley 1939); however, fry use may cause vocabulary to decline in spite of its resistance to change. It is unclear whether these effects will be permanent. More research is needed to distinguish any short-term effects from long-term effects. One limitation of this study is the small sample size. However, even with this limited sample, the effects were strong enough to have statistical significance. Due to the nature of this study, we were unable to determine the contents of the specific substances the experimental group used. Thus, we are unable to determine if the effects on vocabulary and abstract thinking are due to formaldehyde alone, PCP, or the effects of some other combination of substances. Any future research should involve a larger sample and a longitudinal study of fry users focusing on their long-term cognitive impairments. In any case, the aim of this study--to add to the knowledge of the neuropsychological effects of using formaldehyde in the form of fry (marijuana or tobacco cigarettes dipped in formaldehyde embalming fluid laced with PCP)--has been accomplished.


Connecticut Clearinghouse. 2002. Embalming Fluid. [Brochure]. Plainville, CT: Connecticut Clearinghouse. Available at /Embalming-Fluid-IlyWet-Fry.pdf.

Elwood, W.N. 1998. Fry: A Study of Adolescents' Use of Embalming Fluid with Marijuana and Tobacco. Austin: Texas Commission on Alcohol and Drug Abuse. Available at

Hammack, S. (Ed.) 1998. Fry: The new drug on the block. Disease Prevention News 58 (13): 1-13.

Hawkins, K.A.; Schwartz-Thompson, J. & Kahane, A.I. 1994. Abuse of formaldehyde-laced marijuana may cause dysmnesia. Journal of Neuropsychiatry and Clinical Neurosciences 6 (1): 67.

Holland, J.A.; Nelson, L.W.; Ravikumar, P.R. & Elwood, W.N. 1998. Embalming fluid-soaked marijuana: New drug or new guise for PCP? Journal of Psychoactive Drugs 30 (2): 215-29.

Klein, M. & Kramer, F. 2004. Rave drugs: Pharmacological considerations. AANA Journal 72 (1): 61-67.

Modesto-Lowe, V. & Petry, N.M. 2001. Recognizing and managing "illy" intoxication [Letter to the editor]. Psychiatric Services 52 (12): 1660.

National Drug Intelligence Center (NDIC). 2004. Fry Fast Facts: Questions and Answers. [Brochure]. Johnstown, PA: NDIC.

Shipley, W.C. 1939. Shipley Institute of Living Scale for Measuring Intellectual Impairment: Manual for Directions and Scoring Key. Hartford, CT: The Institute of Living.

Wilbur, S.; Harris, M.O.; McClure, P.R. & Spoo, W. 1999. Toxicological Profile for Formaldehyde. Atlanta: U.S. Department of Health and Human Services, Public Health Service, and the Agency for Toxic Substances and Disease Registry. Available at

Please address correspondence and reprint requests to Lawrence S. Dilks, Ph.D., Department of Psychology, McNeese State University, PO Box 91895, Lake Charles, LA 70609.

Janice C. Marceaux, M.A. * Lawrence S. Dilks, Ph.D. ** Sheila Hixson, M.A. ***

* Doctoral Student, University of Alabama at Birmingham.

** Associate Professor of Psychology, McNeese State University, Lake Charles, LA.

** Instructor, McNeese State University, Lake Charles, LA.
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Article Details
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Title Annotation:Short Communication
Author:Marceaux, Janice C.; Dilks, Lawrence S.; Hixson, Sheila
Publication:Journal of Psychoactive Drugs
Article Type:Report
Geographic Code:1USA
Date:Jun 1, 2008
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