Counterfeit Pepper Spray: A Case Report

Pepper spray is one of the less lethal instruments used by law enforcement agencies around the world. Basically, pepper spray is composed of the active ingredient, a carrier solvent and a propellant. The purpose of pepper spray, a non-lethal weapon, is to briefly incapacitate and restrain an individual, without causing permanent damage. Therefore, the presence of hazardous substances is undesirable. Pepper sprays confiscated by the Brazilian Federal Police were analyzed to identify their ingredients. Chemical analyses were performed using gas chromatography-mass spectrometry (GC–MS) and Fourier transform infrared (FTIR). The most surprising outcome was the identification of methanol (highly toxic and flammable) as a carrier solvent in the analyzed products, a great concern. Flammable gases (used as propellants) and discrepancies related to active ingredients on product labels were also noted. Therefore, this investigation revealed the serious risk of low quality pepper spray causing damage to both users and other people subjected to its effects.


Introduction
Among the technologies developed as weapons using natural products, pepper spray has become popular as a stunning agent. For this reason, pepper spray has been used as a non-lethal (also known as less-than-lethal, less-lethal, or sub-lethal) resource by law enforcement agencies around the world [1][2][3][4].
Around the world, opinions about the use of this instrument are controversial, which explains why regulations on the use of pepper spray are quite heterogeneous. In the USA, the use of pepper spray is more widespread and is legal throughout the country. However, some states restrict its sale according to the age and criminal record of purchasers, the volume of the device, and the concentration of the active ingredient, and its use against police officers and in schools is forbidden. In Canada, China, Germany, and the UK, the use of pepper sprays on humans is not allowed. Denmark and Brazil authorize its use only by the military and police forces or by private security agents [3]. New legislation is under discussion in Brazil to allow the use of pepper spray as a civilian defensive weapon.
The use of force continuum [5], also known as gradual escalation of use of force [6], is an internationally recognized concept. It consists of a set of actions that are part of the policies used to guide police officers regarding their use of force. Its main purpose is to use the appropriate level of force to resolve a situation. Some examples of levels of escalating actions are the presence of an officer (no force is used), verbalization (non-physical force), empty hand tactics (use of bodily force), less-lethal methods (conducted energy devices, pepper sprays, etc.) and lethal force (firearms) [5]. Thus, pepper spray is an important instrument covered by this concept [7].
Pepper spray is applied by spraying the liquid directly on an individual's face, temporarily incapacitating him and thus giving the police officer or third parties a self-defense advantage. Therefore, it is widely used in crowd control. Pepper spray inflames the mucous membranes and produces a sensation of intense burning of the skin. When sprayed into the eyes, it can cause temporary blindness and severe pain, inducing fear and disorientation. The effects last for 10 to 15 min, but after a few hours, the individual should feel fully recovered, without suffering any permanent ill effects, i.e., no irreversible damage. The main expected effects are immediate and involuntary closing of the eyes and tearing, and common side effects are burning eyes, coughing, nasal discharge, difficulty breathing, burning sensation in the mouth, and other reactions [8,9].
From a chemical point of view, the active components of pepper spray are derived from oleoresin capsicum (OC), a viscous liquid extracted from the fruit of pepper (capsicum). OC contains over one hundred different substances, consisting of complex mixtures, mainly of lipophilic molecules. Capsaicinoids are the pharmacologically active and pain-producing components of hot pepper. The characteristic chemical structure of capsaicin (or its analogues) contains a vanillylamide moiety (4-hydroxy-3-methoxybenzylamide) and an acyl chain containing 10 to 11 carbon atoms. The components that stand out among capsaicinoids are capsaicin (E-8-methyl-N-vanillyl-6-nonenamide), dihydrocapsaicin (8-methyl-N-vanillyl-nonanamide), and nonivamide (N-vanillyl-n-nonanamide) [10,11].
Capsaicin and dihydrocapsaicin correspond to 90% of the total capsaicinoids contained in pepper fruit, while nonivamide is found as a minor component in Capsicum peppers. However, nonivamide can be synthesized (pelargonic acid vanillylamide -PAVA) as a synthetic form of capsaicin. PAVA is much less irritating than capsaicin and can be produced synthetically on an industrial scale. Moreover, nonivamide is about 60% less pungent and spicy than capsaicin and the cost of synthesizing it is less than 10% that of capsaicin, making it very attractive as a substitute for capsaicin in its applications [12]. Pepper spray can be produced using either a single active ingredient or a combination of OC and PAVA. Nonivamide is naturally present in pepper extracts, but when a pepper spray solution is produced with added PAVA, the amount of nonivamide is much higher than its natural occurrence [13].
Pepper sprays often contain other chemicals that may pose fire or other health and safety hazards. Commonly, substances such as phenols, acids, alcohols, aldehydes, carotenes, esters, oils, and resins are also present in the product. A common additional chemical is the propellant, i.e., a substance which can propel a solution from a container over a sufficient distance for the chemical irritant to reach the target. Another common component is the solvent, which can carry the active chemical, allowing deeper penetration into skin, as well as greater amounts of irritant to be dissolved and dispersed, increasing some of the effects caused by pepper spray. The main propellants are freon, tetrachloroethylene, and methylene chloride, while the main solvents are isopropyl alcohol, tetrachloroethylene and methylene chloride [14].
As a less lethal weapon, the purpose of pepper spray is to briefly incapacitate the target, simply to restrain him but not to cause permanent damage. Therefore, the presence of flammable and/or toxic substances that can cause permanent damage is completely undesirable. In Brazil, only the military and police forces are permitted to use pepper spray, which means its sale to the civilian population is banned and explains why smuggled products are quite common. These products are not subject to quality control by domestic regulatory agencies, which increases the risk not only of distribution of products containing hazardous substances but also of considerable harm to users and third parties. Other countries also experience this problem. In 2018, Mace Security International, an American manufacturer of personal safety and security products, announced the creation of a seal aimed at differentiating counterfeit, inferior and imitation pepper spray products in the United States and around the world [15].
Identification of "natural" capsaicin in sprays can be accomplished using a variety of analytical techniques, such as thin layer chromatography (TLC), high-performance liquid chromatography (HPLC), infrared spectrophotometry (IR), and gas chromatography/gas spectrometry mass (GC/ MS) [16].

Samples
Three boxes containing ten sprays from three different brands confiscated by Brazil's Federal Police. Two sprays of each brand were sampled for the analysis of this study. Figure 1 shows the images of each product.
The purpose of this work is not to assess the quality of the manufacturers, but rather to draw attention to the danger smuggled products represent to the population; however, the general characteristics of each product obtained through visual observations are briefly discussed in the "Vissual Observation" section.

Standards and Chemicals
Nonivamide, natural capsaicin, and n-alkane (C 7 -C 40 ) reference standards were purchased from Sigma-Aldrich®. Ortho-chlorobenzylidene malononitrile confiscated by the Federal Police (identified by GC-MS and FTIR analysis). High-performance liquid chromatography (HPLC) grade methanol and chloroform were supplied by the company Tedia Brazil Produtos para Laboratórios. Solutions of the reference standards were prepared by dilution with methanol. Grade 5 Helium supplied by IBG-Indústria Brasileira de Gases was used as carrier gas for the GC-MS analysis. Natural capsaicinand* "Op[timal", "eleents", "raider,s", "capsaicinand", "inskin" Sample C CS (ortho-chlorbenzylidenmalononitril) -

Fig. 2
Representative spectrum of confiscated pepper sprays (black line) compared to the database FTIR spectra of nonivamide (blue line), natural capsaicin (red line) and CS gas (green line)

Fourier Transform Infrared
Pepper spray samples were analyzed in a Thermo Scientific Nicolet Is10 FTIR Spectrometer equipped with an ATR (attenuated total reflectance) accessory and with a DTGS detector operating at room temperature. The analyses were performed in two ways: (i) direct application of the samples to the ATR crystal and immediate measurement before evaporation of the solvent, and (ii) after obtaining the dry extract by evaporating the solvent from the samples at 50 °C, followed by re-extraction with chloroform. After evaporation of the chloroform, the extracts were analyzed directly on the ATR accessory. Spectra were obtained by 16 co-added scans measured with a resolution of 4 cm −1 in the 4000-650 cm −1 range. Spectra collection and analysis were performed using OMNIC 8.1.0.10 software (Thermo Fisher Scientific, Waltham, MA, USA).

Gas Chromatography-Mass Spectrometry
For the GC-MS analysis, the contents of each pepper spray sample were poured directly into the GC-MS vials. They were then analyzed using two different methods, one to identify volatile solvents and the other to identify active substances.
The GC-MS analysis were performed on an Agilent 6890 N gas chromatograph coupled to an Agilent 5973 mass selective detector and Agilent 7683B autosampler.

Visual Observation
Before the chemical analysis, pepper spray packaging and bottles were visually inspected, which revealed the low quality of these products. Spelling and/or grammatical errors were found on the labels of one of the products (Table 1 -sample A), as well as malfunctioning nozzle sprayer, in all products, which leaked and backfired upon being pressed, spraying the solution onto the user's hands. All products provide information regarding flammability care, but none of them inform the solvent or propellant used. Table 1 shows the samples identifications, the active ingredients listed on their labels and the spelling and/or grammatical errors found on the labels of one of the products.

Chemical Analysis
The results obtained by means of chemical analyzes were quite similar for all products studied, thus, to avoid the tedious repetition of images, only the results obtained for the sample identified as sample A will be displayed in the results.
Infrared spectroscopy (IR) is a simple and efficient tool to identify active ingredients in manufactured products. In the case of pepper spray, the presence of natural capsaicin (capsaicin + dihydrocapsaicin) and nonivamide can be detected. Figure 2 shows the FTIR spectrum of Sample A after chloroform extraction and evaporation of the solvent and database FTIR spectra of nonivamide, natural capsaicin, and CS gas.
The results of the infrared analysis of the three pepper sprays brands were basically the same. The FTIR spectra of the samples were quite similar to the nonivamide spectrum stored in the database, with the most important and characteristic bands corresponding to N-H stretching vibration (3288 cm −1 ), aliphatic C-H stretching vibration (2923 cm −1 and 2853 cm −1 ), C = O stretching vibration (1639 cm −1 ), aromatic C-C stretching vibration (1514 cm −1 ), N-H bending and C-N stretching vibration (Amide) (1514 cm −1 ), and C-O-C asymmetric stretching vibration (1273 cm −1 ) [17,18].
The identification of nonivamide and the absence of natural capsaicin and ortho-chlorobenzylidene malononitrile in the samples were confirmed based on GC-MS analysis, as illustrated in Fig. 3. The GC-MS analysis of the three pepper spray brands revealed basically the same results. Identification of the active ingredient in manufactured products was based on similarities between the samples and standard reference material. The chromatogram of sample A shows a single peak with the same retention time as the nonivamide standard (Fig. 3a). In addition, the mass spectrum of this peak showed a pattern of fragmentation identical to that presented by the nonivamide standard, with the most important and characteristic fragments at m/z 195, 178, 151, 137, 122, 94, and 41 (Figs. 3b and 3c) [19]. No peaks were detected in the retention times presented by the standards of natural capsaicin (mostly capsaicin and dihydrocapsaicin) or ortho-chlorobenzylidene malononitrile. Moreover, no m/z fragments characteristic of these compounds were found. (Fig. 3d-f).
In addition, alkane standards (C 7 -C 40 ) were used to determine the linear retention index (RI) for all substances identified in Fig. 3. The retention index of the active ingredient identified in the samples are identical to that calculated for the standard nonivamide (RI 2552, for standard and samples) and differ from the active ingredients indicated on the labels (ortho-chlorobenzylidene-RI 1571; capsaicin-RI 2592; and dihydrocapsaicin-RI 2615). Furthermore, these results are compatible with the RI values available in the NIST 17 MS Database (Agilent Technologies), considering the tolerance according to the methodology developed by Zacca et all [20].
As discussed earlier herein, the chemical analysis revealed the presence of active ingredients that do not match the compositions described on their labels, indicating that they are counterfeit or falsified products. Table 2 compares the active ingredients listed on the labels of the confiscated sprays and those identified in our analysis.
Sample A merits an additional comment. The active ingredient that appears on the label of spray A is ortho-chlorobenzylidene malononitrile, i.e., technically, this spray is tear gas and not pepper spray. As mentioned earlier, the only component identified by chemical analysis was nonivamide. Therefore, the label on this sample is completely misleading. As for the other two sprays, B and C, whose labels list natural capsaicin and capsicum oleoresin, respectively, as active ingredients, they are also at odds with our chemical analysis, which basically revealed the presence of nonivamide and the absence of capsaicin, the main capsaicinoid of both natural capsaicin and OC.
As can be seen in Fig. 4, the GC-MS analysis also indicated the presence of traces of n-nanoic acid (Fig. 4a) and the trimethylsilyl derivative (TMS) of nonivamide (Fig. 4b). n-nanoic acid can be used as a precursor in the synthesis of nonivamide [12]. The TMS derivative of nonivamide is not a naturally occurring compound. It can be obtained by means of silylation (introduction of a triorganosilyl moiety, especially the trimethylsilyl species (TMS), into organic compounds), a reaction widely used in organic synthesis [21][22][23]. Thus, in addition to the prevalent presence of nonivamide and the absence of other capsaicinoids, the presence of n-nanoic acid and TMS-nonivamide suggests the nonivamide is of synthetic origin. Again, this contradicts the information given in the labels of samples B and C, since  Fig. 4 Comparison of representative mass spectrum obtained from the samples (black lines) and NIST 2.3 mass spectral library (blue lines) of n-nanoic acid (a) and nonivamide, TMS derivative (b) the terms "natural capsaicinoids" and "Oleoresin capsicum" refer to products of natural origin. The other components of the pepper sprays, i.e., solvents and/or propellants, were also subjected to chemical analyses. FTIR spectra obtained directly from non-pretreated samples basically identified methanol (Fig. 5a). The main characteristic bands are O-H stretching vibrations (3307 cm −1 ), C-H bond stretching (2944 cm −1 ), and stretching vibrations of the C-O bond (1449 cm −1 , 1115 cm −1 , and 1020 cm −1 ). Fig. 5b and c illustrate the result of the GC-MS analysis,  Pepper spray is applied by spraying it into the eyes of the target individual. Therefore, the presence of methanol as a solvent is dangerous. Methanol poisoning can cause irreversible neurological sequelae. Although ingestion is the most common route of contamination, methanol can also be absorbed by inhalation and dermal exposure, which are less common routes of chronic and acute poisoning. Studies on chronic methanol poisoning, particularly through skin absorption and inhalation, are scanty, but the few existing studies describe the possibility of serious problems associated with this type of poisoning, such as loss of vision and severe metabolic acidosis, parkinsonism, and cerebral vasculopathy [24,25].
The GC-MS analysis also indicated the presence of propane and butane in the samples, suggesting that these substances are used as propellants in the analyzed sprays. Figure 6 compares a representative mass spectrum of the samples (black lines) and mass spectra (blue lines) of propane (Fig. 6a) and butane (Fig. 6b) in the NIST 2.3 library.
Concerns about the flammability and toxicity of pepper sprays are well known and have been widely discussed for some time [13,[26][27][28][29][30][31]. In general, solvent carriers and propellants are the flammable components of greatest concern. Thanks to the widespread development of pepper sprays, less flammable and toxic substances are now commonly used, such as ethanol, water, propylene glycol, and isopropanol. With regard to flammability, almost every formula contains some proportion of alcohol to prevent the mixture from freezing, and its flammability depends on this amount, which is often a limiting factor [26]. Holopainen et al. (2003) described the toxic effect of the carrier in a pepper spray, based on a study in which an individual was exposed to a pepper spray with no active ingredient, i.e., with only carrier. This individual, exposed only to the carrier, suffered corneal erosion similar to that of people exposed to spray with an active ingredient [28].
The use of methanol in this type of product is entirely unjustified, given the ready availability of various alternative and less toxic carriers. This finding was the main motive for carrying out this work, since, to the best of our knowledge, the use of methanol as a carrier solvent in pepper sprays has not been reported in the literature prior to the date of this study.
It is noteworthy that the presence of butane, propane, n-nanoic acid, and nonivamide-derived TMS was not unequivocally identified, since only mass spectra were obtained for them. It was not possible to carry out other analysis techniques or determine the retention index due to the low concentration and low resolution of the peaks in the GC-MS analyses. As the conclusion of this work is independent of the presence or absence of these compounds, major efforts were not made to identify them unequivocally, but it was decided to keep them here, as they seem interesting as a complement to the discussion.

Conclusions
This study strongly indicates, based on comprehensive chemical analyses and visual inspection of the packaging and containers of three brands of pepper spray confiscated by the Brazilian Federal Police, that these products are counterfeit or falsified. This conclusion is based on several findings, such as (i) discrepancy between the active ingredients described on the labels and the substances identified by chemical analysis; (ii) spelling errors on the label of one of the products, which is rare in non-counterfeit/falsified products that undergo quality control; (iii) malfunction of the triggering mechanism, causing leaks onto the user's hands, and (iv) the presence of methanol as a carrier solvent in the analyzed products, the most alarming finding of this work.
In general, the mere fact that these products are counterfeit or falsified indicates the absence of quality control, which causes considerable uncertainty about the use of this type of product as a non-lethal weapon. In the specific case of this study, there are two other relevant issues besides the absence of quality control. The first issue is flammability, since propane and butane were identified as propellants, and this is a fairly recurrent problem [27]. The second issue, which is quite unusual, concerns the use of methanol as a carrier solvent. This substance is not only flammable but also highly toxic, even via inhalation and dermal exposure [24,25], and should therefore be avoided in the composition of pepper sprays and related products.
The use of pepper sprays such as those described herein, which use methanol as a carrier solvent, can, in theory, cause acute poisoning of people that are deliberately targeted, and also pose risks of chronic poisoning among police and other security agents that frequently apply pepper spray in their line of work. Thus, such products should be subjected to quality control upon their acquisition, especially by the police forces, given their often very low quality and high risk of harming both users and others, as found in this study. authors read and approved the final manuscript. All authors prepared Figs. 1-6.
Funding Partial financial support was received from Coordination for the Improvement of Higher Education Personnel (CAPES) through a scholarship for one of the authors (Amanda das Graças Barbosa).

Data Availability
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations
Ethical Approval and Consent to Participate Not applicable.
Human and Animal Ethics Not applicable.

Consent for Publication
All authors consent to publish and gives the publisher the permission to publish the work.

Competing Interests
The authors declare no competing interests.