Evaluation of commercially available methamphetamine presumptive tests for site contamination

Abstract

Presumptive tests or lateral flow immunoassay testing kits are increasingly being utilised as a fast, portable, cost-effective method to detect an array of analytes, particularly illicit drugs. In Australia, the methamphetamine and decontamination industry regularly use presumptive testing kits to determine whether a property is contaminated. These presumptive test kits advertise a detection limit of 0.5 µg/100 cm² and above for methamphetamine. The performance of seven methamphetamine presumptive test brands and their kit components were analysed in this study. Following the kit instructions, each kit was analysed using a ceramic tile that was spiked with a known concentration of methamphetamine. These presumptive test kits were highly sensitive, with positive results also found below the limit of detection. Therefore, if there is a negative result it is likely that there is no methamphetamine present. Those that return a positive result require further quantitative assessment. Thus, the presumptive test kits may detect the presence of methamphetamine that is below the Australian Clandestine Drug Laboratory Remediation Guideline of 0.5 µg/100 cm². This indicates these tests might be useful as a screening assessment but should not be relied upon to develop a remediation action plan.

Keywords:

• Third-Hand exposure
• presumptive tests
• testing and remediation
• methamphetamine contamination
• lateral flow assay

Introduction

Worldwide, the use of methamphetamine is an issue of increasing concern, with the number of users growing [1–4]. Both clandestine laboratories used to manufacture methamphetamine, and the smoking of this drug, release vapours that contaminate the surrounding environment, including houses, hotel and motels and cars [5–7]. These residues deposit on surfaces and can become embedded in porous materials in exposed areas such as carpets, gyprock and furnishings [8–10]. Research has also found that possessions introduced post-smoking or post-cooking into a contaminated environment will also become contaminated with methamphetamine [11]. Health effects can arise when the methamphetamine subsequently desorbs from these surfaces and materials, and people are exposed to the methamphetamine - days, months or even years later [11–15]. Notably, new residents that are unaware of the history of the property can be exposed to these methamphetamine residues, which can result in adverse health effects [12,16]. Headaches, itchy, watery eyes, insomnia, respiratory, and behavioural and cognitive issues have been reported in people, including children exposed to methamphetamine contamination [12,16–18].

When there is suspicion that a property is contaminated with methamphetamine, owners engage methamphetamine testing companies to determine the level of contamination. The Australian Clandestine Drug Laboratory Remediation guidelines have set a health guideline limit in residential settings of 0.5 µg methamphetamine in a 100 cm² sample [19]. Remediation is required for samples that exceed this contamination value [20]. This guideline was developed to educate and ensure a range of stakeholders understood the requirements and expectations involved in remediating a contaminated property in Australia [20]. This remediation limit can vary depending on the country and even state or province. For example, in the United States, Washington has a limit of 1.5 µg/100 cm²; Michigan has a limit of 0.5 µg/100 cm²; and Connecticut requires anything above 0.1 µg/100 cm² as requiring remediation [21–26]. Whereas, New Zealand’s remediation limit was 0.5 µg/100 cm², then a standard limit of 1.5 µg/100 cm² was developed, and a limit increase to 15 µg/100 cm² is currently being proposed [21,27].

Currently in Australia, there are no legislative nor regulatory controls for the methamphetamine testing and decontamination industry [21]. This has resulted in no accreditation processes, and a wide range of techniques being used and no standardisation to the practices being used [28]. One common practice is the use of lateral flow immunoassay testing kits that develop an extra line when methamphetamine is not present in the sampling buffer solution. Lateral Flow Assays (LFA) are a low cost and transportable method of analysis that provides quick results [29]. The LFA technology has been adapted to detect a wide range of analytes including pesticides, microorganisms, metals, toxins, human proteins, and contaminants [29,30]. The methamphetamine LFA tests, also referred to as presumptive tests, advertise that they can detect various different mass thresholds for methamphetamine. In Australia, the LFA tests sold and used, claim a threshold or detection limit of 0.5 µg methamphetamine in a sample, however, there has been no independent testing undertaken to validate these claims. This study aimed to determine the efficacy and accuracy of these tests.

Materials and method

Ordering test kits

Company websites that advertised and sold methamphetamine-specific presumptive test kits in Australia were identified and six kits were ordered from the suppliers’ websites. There was also one brand of test kits that were donated by the supplier when they heard about the study. Although seven methamphetamine testing kits came from separate websites and suppliers, the testing kits appeared to be from three manufacturers. This inference could not be verified, however each test kit appeared visually distinctive. This could indicate that tests were purchased in bulk and rebranded by the suppliers which increased the sample size of the test kit analysis. Notwithstanding, the test kit brands will be referred to as Brands 1 to 7.

Surface preparation

To ensure the performance of the presumptive test kits could be analysed, a non-porous surface was selected and cleaned [31,32]. Commercially available and commonly used, ultra white gloss ceramic bathroom tiles (Johnson Tiles, China) were purchased. All tiles were cleaned with 70% ethanol solution (Chem-Supply, Australia), then cleaned through a rinse cycle in the laboratory dishwasher (Miele®, Germany) at 15 °C for four minutes.

Methamphetamine standard preparation

Analytical grade methamphetamine (Cayman Chemical, United States) was used for all tests. The methamphetamine was suspended in methanol (Chem-Supply, Australia) and then prepared into varying concentrations of 0.18, 0.24, 0.6, and 0.7 µg per 100 µL. This was confirmed by quantitative liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis (ACS Laboratories (Australia), Victoria), that followed the National Institute for Occupational Safety & Health (NIOSH) standard 9111 [33].

Experimental method

Methamphetamine of each concentration was deposited on the surface of a ceramic tile in individual droplets using a micropipette. These were prepared in triplicate (three ceramic tiles). Each tile was left for 10 min to allow the methanol to volatilise and the methamphetamine deposits to dry on the surface.

Individual test kit instructions were followed and notably, each of them differed. However, as a generalisation, swabs were removed from their sterile packaging and dipped into the liquid buffer provided. The surface was then swabbed within a 100 cm² template square, following a zig zag motion on the tile, from left to right, then up and down, and left to right again, as per the Australian Voluntary Code of Practice [34]. The swab was returned to the buffer where it was agitated within the bottle for several seconds and then removed. The buffer bottle was shaken for 20–30 s to homogenise the liquid, and then 3–4 drops were administered to the cassette with 2–5 s intervals. The length of time required to wait for red lines to appear ranged from 30 s to 5 min. Results were read after 5 min, but before 10 min to ensure the readings were still valid. All presumptive test kits had the same method of displaying the result. With the exception of one brand, all of the test kit cartridges gave a positive result for one line furthest away from the well, two lines was a negative result, and one line closest to the well was an invalid result. The other brand had similar results for the single and double lines, but different positioning away from the well. This process was repeated for all of the methamphetamine standards, and each test kit was repeated in triplicate.

For the analytical positive control, wipes (Teri Wipers®, United States of America) were dampened with 3 mL methanol. The aim was to deposit a known concentration on to the ceramic tile with methanol, which would evaporate and the known mass would remain. This was to allow for a direct comparison with the Australian guideline of 0.5 µg/100 cm². Thus, 100 µL of each methamphetamine concentration was aliquoted onto a ceramic tile, left for 10 min to dry, and then wipe sampled using the standard procedure described above (the Australian Voluntary Code of Practice [34]). These same methamphetamine concentrations were also put directly by micropipette onto a wipe as a positive control. The negative controls of methanol only, and the positive controls were sent to ACS Laboratories (Australia). Quantitative liquid Chromatography with tandem mass spectrometry (LC-MS/MS) analysis was used following the National Institute for Occupational Safety & Health (NIOSH) standard 9111 [33].

Results

For the purposes of this research “accurate” means either that the test returned a negative result when there was less than 0.5 µg/100 cm² methamphetamine added to the tile, or returned a positive result when there was more than 0.5 µg/100 cm² methamphetamine added to the tile. Overall, of the 72 test kits, 59% returned an accurate result.

The test kits from Brand 3 were two months past their expiry date when the experiment was conducted. These expired test kits detected 0.7 µg/100 cm² (an accurate result), but also returned an inaccurate result with 2/3 positive results for 0.18 µg/100 cm² (which is considered to be below the detection limit). The results for this brand have been excluded from the rest of the results and most of the discussion.

Notably, 26 tests returned a positive result when there was methamphetamine present, but with less 0.5 µg/100 cm² methamphetamine added to the tile, despite 0.5 µg/100 cm² being their advertised limit of detection. This was for both 0.18 µg and 0.24 µg/100 cm² (Table 1), with Brands 1, 4 and 5 inaccurately giving a positive result in all of the tests.

Table 1. Results from the presumptive tests for each brand (✓ indicates an accurate result, O indicates an incorrect result below the limit of detection, X indicates a false negative result).

Concentration (µg/100 cm^2)	Brand 1	Brand 2	Brand 3^a	Brand 4	Brand 5	Brand 6	Brand 7
0.7	✓✓✓	✓✓✓	✓✓✓	✓✓✓	✓✓✓	✓✓✓	✓✓✓
0.6	✓✓✓	^b	^b	✓✓ X	✓✓✓	^b	✓✓ X
0.5 µg/100 cm^2 – stated limit of detection for all kits
0.24	O O O	✓✓✓	✓✓✓	O O O	O O O	✓✓✓	^b
0.18	O O O	O O ✓	O O ✓	O O O	O O O	O O O	O O O
0	✓✓✓	✓✓✓	✓✓✓	✓✓✓	✓✓✓	✓✓✓	✓✓✓

Most kits were tested three times for each concentration.

^aBrand 3 was out of date and so results should be interpreted with caution.

^bIndicates that this test was not performed on that brand.

Two of the tests returned a negative result when there was more than 0.5 µg/100 cm² methamphetamine added to the tile (Brand 4 and Brand 7). For both of these brands, the negative result was one out of three tests, with the other two tests being positive. All of the test kits accurately produced a negative result for the 0 µg methamphetamine/100 cm² (Table 1). These results indicate that the test kits are more sensitive than advertised, with many tests showing methamphetamine contamination at levels below their stated limit of detection of 0.5 µg/100 cm². This contrasts with the 100% accuracy for all of the negative tests, which were correctly identified as negative.

Discussion

Products that are manufactured and mass produced inevitably produce some with imperfections and others that malfunction [35]. Quality control and product testing is therefore an imperative step in the manufacturing process [36]. It has been argued that it should be the responsibility of the manufacturer to provide the statistical quality control data to the supplier [37,38]. This information should then be passed onto the consumer to ensure that they understand the risks or limitations of the product and are making a sound decision when they select the product.

For the purposes of this study, an accurate result was when the test kit correctly identified the presence or absence of methamphetamine corresponding with the concentration tested. Hence, a negative result was any incorrect result according to the concentration tested. This includes positive results below the limit of detection.

However, when the brands we purchased have supplied customers with quality control data, the information is stated as positive and negative percentages. These statements can be confusing or misleading, as it has been established in this study that test kits can have a positive result for methamphetamine below the advertised limit of detection. Thus, it is not clear whether the quality control data actually represent zero methamphetamine or below 0.5 µg. Brand 3 stated the accuracy of the test as 93.7% positive and 98.2% negative, while Brand 1, 5 and 6 all claimed to have 97.45% positive and 99.38% negative test results (Table 2). The remaining brands did not provide the quality control data to the consumer.

Table 2. The quality control data provided to customers in the methamphetamine presumptive test kits.

Brand	Negative (%)	Positive (%)
1	99.38	97.45
2	N/A^a	N/A^a
3	98.2	93.7
4	N/A^a	N/A^a
5	99.38	97.45
6	99.38	97.45
7	N/A^a	N/A^a

^aN/A means that there were no quality control data provided.

Based on the results of this study, these presumptive tests are more sensitive than reported and produce a high number of positives for concentrations below their stated limit of detection. This has serious public health implications since it would increase the financial burden, time spent and stress for both those residing within the property and those that own it. It is therefore clear that a positive result from a lateral flow test should be considered only as a prompt for further quantitative testing, not as a definitive result. Decisions based on the presumptive tests alone is a reported concern [28], especially for illicit drugs [39–43]. If not used appropriately, these tests can provide the opportunity and financial incentive for businesses to offer remediation services to those that do not require it.

According to the New Zealand Standard 8510:2017 (NZS), all methamphetamine testing kits must be validated by an organisation that is accredited by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) 17025 [22]. Any validation studies must be publicly available and listed on their website. Test kits should also be re-analysed at 12 monthly intervals or if there is a change in the standardised limit of methamphetamine, or any performance issues or risk of being compromised [22]. The Institute of Environmental Science and Research Limited (ESR) was contracted to independently test and analyse a particular brand of presumptive tests in line with the NZS [44]. According to the NZS, the methamphetamine contamination limit is 1.5 µg/100 cm², therefore the test kits passed the Standard’s published criterion [44]. These kits are sold and distributed in locations with a lower accepted limit, thus they were tested for 1.5 µg/100 cm², but not the 0.5 µg/100 cm² as per the Australian Guidelines.

Ciesielski, Wagner [18] found that using methamphetamine test kits that were developed by Health Effects Laboratory Division at the Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health, had a high degree of specificity and sensitivity. These kits were able to detect methamphetamine at a level 25 times lower than their limit of detection with 95.08% specificity and 88.57% sensitivity [18]. Reassuringly, in our testing only 0.07% of all tests failed to detect methamphetamine when it was present above the limit of detection. However, the significant number of tests returning positive results below the stated limit of detection should reinforce the idea that this is a prompt for further quantitative testing and should not be considered an accurate result.

The tests ranged in price from AU$13 to AU$18 per sample. The test kits came with various components, and a number of kits were missing vital components (Table 3). The testing kits we purchased are advertised to the general public, who may not have any prior knowledge or understanding of methamphetamine contamination, so it is important that the components are all there, and that the instructions are clear.

Table 3. The components that were Included in the kits that were tested in this study.

	Price per Test AU$	Transit to Adelaide	Swabs	Test	Buffer	Gloves	Template	Glove Change	Blank Test	Quality Control
Brand 1	17	7 days	✓	✓	✓		✓	✓	✓	✓
Brand 2	N/A	N/A	✓	✓	✓	✓
Brand 3	13	7 days	✓	✓	✓	✓	✓			✓
Brand 4	18	2 days	✓	✓	✓	✓
Brand 5	15	15 days	✓	✓	✓		✓	✓	✓	✓
Brand 6	15	16 days	✓	✓	✓		✓	✓	✓	✓
Brand 7	18	7 days	✓	✓	✓		✓

Each of the kits were missing at least one component that could affect the outcome of the test. Missing components all differed. Several brands recommended changing gloves between tests but did not provide any, the swabbing area was always based on 100 cm² and some suppliers did not provide a template. A number of kits did not contain recommendations for consumers to conduct their own blank test.

Recommendations

The outcome of this study demonstrates that the presumptive methamphetamine testing kits are simple to use but are prone to inaccurate results as concentrations decrease. It seems clear that the accuracy of a test is impaired over time. The expired test kits from this study were only two months out of date but yielded significantly more inaccurate results compared with the other test kits. However, it should be noted that it is possible that this might not be the result of the kit, but simply due to being out of date.

Due to the high number of positives below the limit of detection, these tests should be used as a screening tool, but this should always be followed with quantitative analysis prior to the development of a remediation action plan. This is supported in the literature [34]. There have been reports that some occupational hygienists are using presumptive testing methods when validating that a contaminated property has been adequately remediated [28]. This is an unacceptable practice due to the accuracy and validity of these presumptive test kits. Quantitative wipe samples that are sent to a National Association of Testing Authorities (NATA) accredited laboratory should be the only tests accepted and recognised [34].

Limitations

It is understood that the methamphetamine found within residential properties is not an analytical grade methamphetamine, as was used in this study. It was important to use methamphetamine with minimal impurities to ensure those unknown substances were not producing inaccurate results. Future research could explore the impact of these impurities on the reliability of the test results. In addition, there are other factors not tested for in this study that may affect the accuracy of the results provided by presumptive test kits. For example., these kits have been designed for use by commercial testing, cleaning companies and also members of the public. Consequently, the use of these kits by inexperienced persons may add additional variation to the results compared with those presented in this study, where the testing was performed by laboratory trained researchers. Also, the glazed ceramic tiles used in this study are non-porous and easily cleaned. Variations in recovery from different surfaces would impact the accuracy of the results provided by the presumptive test kits [9,31,32,45].

Conclusion

The low cost of presumptive kits for methamphetamine testing means that they provide a valuable tool for initial screening. Our study indicates that the tests did not detect methamphetamine when it was not present but did detect low levels, below the detection limit of 0.5 µg/100 cm², which might cause significant stress and anxiety. It is therefore recommended that any positive result be confirmed with quantitative testing and that no decisions about remediation, nor remediation success, are made based on positive presumptive test kit results. These tests should be used only as a preliminary screening tool and the results externally validated. It is recommended that mandatory quantitative assessment after screening returns a positive result be required. This will not only improve testing and decontamination practices, but also increase public trust and perception of the industry.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The first author was funded by The Australian Government Research Training Program Scholarship; otherwise, there was no external funding.