A comparative analysis of heavy metals present in cigarette and cigarette leachate


 Smoked cigarette and butts are the most common forms of litter globally. The local water bodies and their compartments have been severely polluted by the accumulation of these litters and the cumulative effect of many cigarette butts littered in a centralised area may present a significant threat to the living organisms. It is essential to study the leaching behaviour of cigarettes to understand how the heavy metals are leached out into the aquatic ecosystem. In this context, we determined the concentration of different metals (such as Cd, Cu, Fe, Pb, Sn, Zn & Hg) leached from the different brands of unsmoked and smoked cigarette and cigarette butts by using Atomic Absorption Spectrometry. The results revealed that the amounts of heavy metal are higher in butt samples (USB and SB) of both cigarette and leachate irrespective of brands, compared to the tobacco part of the cigarette and the concentrations of certain toxic heavy metals in cigarettes were significantly different between cigarette brands tested. These results suggest that cigarette litter was found to be one of the major sources of metal contamination in the aquatic ecosystem and apparent leaching may increase the risk of toxicity to aquatic organisms.


Introduction
Smoked cigarette and butts are the most common forms of litter globally, where the common people can be present, especially on the waterways, the roads, the parks etc. (Habre et al. 2014;Robinson 2005).
About 6 trillion cigarettes are found to be smoking every year globally and one of the largest wastes generated in our society, which represent around 13% of total items collected in the international coastal cleanup (Mohajerani 2016) thrice as much as any other type of litter. The local water bodies and their compartments have been severely polluted by the accumulation of these litters (El Tokhi 2017) and the cumulative effect of many cigarette butts littered in a centralised area may present a signi cant threat to the living organisms (Slaughter et al. 2011;Micevska 2006).
There are two types of cigarette smoking, mainstream smoking (MSS), the smoke inhaled by the smoker, and sidestream smoking (SSS), the smoke is released from the tip of the cigarette in between puffs.
Several studies say that SSS contains higher levels of a cancer-causing substance (Micevska 2006).
Although the presence of various compounds present in cigarettes and butts and mainstream smoke have been extensively studied, a few reports are available on the amount of these components leached from cigarette and cigarette butts (Micevska 2006;Moriwaki 2009). The heavy metals and trace elements present in the cigarette butt leachates are the reason for the toxicity in the organisms (Micevska 2006).
The occurrence of heavy metals in cigarettes is largely due to the soil condition where the tobacco (Nicotiana tabacum) is being cultivated (Talhout et al. 2011;Register 2000). Apart from that, the application of pesticides, insecticides and herbicides also introduce metals to the tobacco leaf (Ontario 1994). Also, metals are accumulated during the manufacturing of cigarette, essentially through the addition of casing materials to the cured leaves (Baker et al. 2004a, b) and the use of brightening agents on the wrapping paper (Mussalo-Rauhamaa et al. 1986;Iskander et al. 1986;Iskander 1985;Owens 1978). Most of the chemicals produce new compounds when it is burned (Novotny et al. , 2009).
Due to the accumulation of various heavy metals in the water bodies, the response of aquatic biota to heavy metal contamination is highly varied (Kabata-Pendias and Pendias 2001;Mason 1991). Also, physical parameters, such as pH, affect the mobility of metals in the sediments further in uence the biological responses and the bioavailability of metals to the aquatic organisms, including plants ( Kabata-Pendias and Pendias 2001). It is essential to study the leaching behaviour of cigarettes to understand how the heavy metals are leached out into the aquatic ecosystem. In this context, the present study aims to determine the concentration of different metals such as Cd, Cu, Fe, Pb, Sn, Zn and Hg leached from the different brands of unsmoked and smoked cigarette and cigarette butts in an aqueous solution and to assess the concentration of metals leached concerning the soaking time of the cigarette samples. The selection of the above metals for the study is based on their presence in smoked lters (Dobaradaran et al. 2017;Mindell 2001;Chiba and Masironi 1992) toxicity to living organisms (Savino and Tanabe 1989).

Sampling of cigarettes
Packs of the three most popular tobacco cigarette brands were purchased from the local shops in Bengaluru, South India. Following collection, the lters and the tobacco part of the cigarettes were cut and separated manually. Cigarettes were sampled as an unsmoked cigarette (USC), smoked cigarette (SC), unsmoked butt (USB) and smoked butt (SB) from each brand (See further) (Fig. 1a). All these samples were stored separately in disposable plastic containers to prevent contamination and moistening caused by humidity in the laboratory.
Unsmoked cigarette (USC): The cigarettes were cut, without smoking, at 1/3 from the top of the cigarette using a sterile scissor and the remaining part (including tobacco and butt) was sampled as USC.
Smoked Cigarette (SC): Cigarettes were smoked arti cially till half of the cigarette (1/3 from the top) and the remaining part was sampled as SC.
Unsmoked Butt (USB): The lter (butt) part of the cigarette was cut and removed and sampled as USB.
Smoked Butt (SB): Cigarettes were smoked arti cially till the butt and sampled as SB.

Smoking of cigarettes
The cigarettes were arti cially smoked as per Micevska et al. (2006). Brie y, ve cigarettes from all the three different brands were smoked separately by placing a lit of cigarette against vacuum, using a plastic bottle lled with water tted provided with an outlet at the hind end of the bottle (Fig. 2). The on and off outlet of water helps in mimicking the action of a smoker (Micevska 2006). The cigarettes were smoked down from the top as mentioned in the previous section.

Preparation of leachates
Leachates of all the above four samples (USB, SB, USC and SC) of three different brands were prepared separately by adding them to the phials of an aqueous solution. All the samples (USC, SC, USB and SB) were allowed to soak in the aqueous solutions for 24 hours. Five duplicates were taken for each sample.
Blank was also prepared in the same manner without the addition of any cigarette material (Slaughter et al. 2011). This procedure is summarized in Fig. 1b.

Heavy metal analysis in cigarette samples
For the analysis of heavy metals present in the different samples of cigarette brands, Eneji et al. (2013) methods was followed. All the samples were cut into tiny pieces using scissors and were washed with about 4ml of 1% HNO 3 . The samples were placed in a mu e furnace using a crucible. The mu e furnace was set at 500 C for 1 hour. The ignited residues were moistened with water. To this, 5ml of 4N HCl was added carefully and the mixture was ltered through Whatman lter paper into a 50 ml volumetric ask. This was diluted to the mark and stored in 4 C for analysis using Atomic Absorption Spectroscopy (AAS model AAA 6880 Shimadzu, with a measurement range of 185-900 nm, photomultiplier tube detector, ame type: Air-C2H2) (Eneji et al. 2013).

Acid digestion of cigarette leachates
Fifty millilitres of leachate were prepared per sample and were subjected to acid digestion using concentrated H 2 SO 4 and concentrated HNO 3 . All glassware and containers used for the process of acid digestion were washed with 1% HNO 3 before the treatment. To the sample, 0.5ml of concentrated H 2 SO 4 and 1ml of concentrated HNO 3 was added and were incubated for 4 hours in a boiling water bath (Matsunaga et al. 1979). After completion of the four hours, the digested samples were ltered into a 50ml volumetric ask using Whatman lter paper. The solution was diluted to 50ml using distilled water and it was stored at 4 C for further analysis using Atomic Absorption Spectroscopy (Model AAA 6880, Shimadzu).

Statistical analysis
All the data were subjected to statistical analysis. Microsoft Excel software was used for statistical analysis. The tools like standard deviation and mean was found out for all the samples and signi cant variation was found out using a graph.

Results
The levels of different heavy metals, such as Cd, Cu, Fe, Pb, Sn, Hg and Zn present in the three different popular brands of cigarettes sold in Bengaluru, Southern India, and were classi ed based on the selling price as expensive, moderate and cheap. Each brand has four samples, like unsmoked cigarette (USC), smoked cigarette (SC), unsmoked butt (USB) and smoked butt (SB). Heavy metals present in these samples (direct) and leachate were analyzed. Levels of heavy metals in the different samples of expensive brand In this brand, the level of Cd was found to be highest in SB (0.52 ± 0.01 µg/g), while the least level was recorded with USC and USB (0.25 ± 0.03 and 0.24 ± 0.02 µg/g respectively). Statistical analysis reveals that the difference in the level of Cd between SB and other samples are signi cant (P < 0.05) whereas the difference between SC and USB and USC are insigni cant (P > 0.05). Among the four samples, the USB and SB registered with the highest level of Cu (151.30 ± 5.76 and 162.94 ± 6.80 µg/g respectively), while the samples SC and USC registered a low level of Cu (73.79 ± 0.36 and 86.61 ± 0.91 µg/g respectively).
The statistical analysis revealed that there is a signi cant difference (P < 0.05) between butts and cigarettes whereas the difference between USB and SB and USC and SC is insigni cant (P > 0.05). The level of iron (Fe) was found to be highest in the USC (105.48 ± 0.39 µg/g), followed by SC and USB (87.93 ± 3.56 and 51.15 ± 2.04 µg/g respectively). The statistical analysis revealed that there is a signi cant difference (P < 0.05) between the different four samples. The level of lead (Pb) was found to be highest in SB (19.86 ± 2.39µg/g), followed by USB and SC (16.97 ± 1.46 and 12.44 ± 1.40 µg/g respectively). The least level of Pb is found in USC (9.97 ± 0.49 µg/g). The statistical analysis on the level of Pb between the samples was signi cant (P < 0.05). The level of tin (Sn) showed the highest trend SB (869.05 ± 19.11µg/g), followed by USB and SC. The least level of Sn is in USC with an insigni cant difference, while USC and SC (599.60 ± 15.98 and 466.88 ± 8.33 µg/g respectively). It was revealed that USC has registered the lowest level for Sn (438.32 ± 2.89µg/g). Statistical analysis on the level of Sn between the samples was signi cant (P < 0.05). The level of zinc (Zn) was found to be high in USB (45.21 ± 1.48µg/g) while the least level of Zn was found in SC (24.40 ± 0.71µg/g). The sample USC (305.34 ± 8.14 µg/g), showed a high amount of Hg while SC least amount of Hg (104.78 ± 3.08 µg/g), with signi cant difference (P < 0.05) (Fig. 3).

Levels of heavy metals in different samples of a moderate brand
The level of Cd was found to be high in the samples SB and USB (1.18 ± 0.08, 1.15 ± 0.07 µg/g respectively), while the least level of Cd was found in USC and SC (0.56 ± 0.01, 0.55 ± 0.08 µg/g respectively). Statistical analysis reveals that the difference in the level of Cd between butts and cigarettes are signi cant (P < 0.05) whereas the difference between SB and USB and USC and SC is insigni cant (P > 0.05). Among the four samples, the USB registered with the highest level of Cu (287.530 ± 43.29 µg/g) followed by the SB (185.35 ± 15.00 µg/g), while the samples SC and USC registered a low level of Cu (96.85 ± 6.04 and 105.07 ± 8.51 µg/g respectively). The level of iron (Fe) was found to be high in the SB (155.30 ± 5.04 µg/g) and low in the USB (112.28 ± 9.73 µg/g). The samples USC and SC registered almost similar value (134.61 ± 5.56 and 139.72 ± 4.34 µg/g respectively). The statistical analysis revealed that the difference between the samples SB and USB is signi cant (P < 0.05), but an insigni cant difference was observed between the samples USC and SC (P > 0.05). The level of lead (Pb) was found to be highest in USB (24.42 ± 1.18 µg/g) and least in SB (2.76 ± 0.10 µg/g), but the samples USC and SC (14.14 ± 1.07 and 12.70 ± 1.68 µg/g) had similar values with an insigni cant difference (P > 0.05). The statistical analysis on the level of Pb between the samples was signi cant (P < 0.05). The level of tin (Sn) showed the highest trend USB and SB (1184.51 ± 10.82 and 1168.60 ± 15.39 µg/g respectively), with an insigni cant difference (P > 0.05), while USC and SC have registered low level for Sn (617.69 ± 17.20 and 567.61 ± 11.69 µg/g respectively) and the difference between the samples was insigni cant (P > 0.05). The level of zinc (Zn) was found to be high in USB (141.92 ± 9.57 µg/g) while the least level of Zn was found in SC (37.10 ± 6.79 µg/g). The samples SB and USB (359.02 ± 19.05 and 331.38 ± 8.09 µg/g respectively), showed a high amount of Hg while USC and SC had a lesser amount of Hg (140.87 ± 4.36 µg/g and 158.36 ± 5.75 µg/g), with the insigni cant difference(P > 0.05) (Fig. 4).

Levels of heavy metals in the different samples of cheap brand
The level of Cd was found to be high in the samples USC and SB (0.12 ± 0.02 and 0.13 ± 0.01 µg/g respectively), while the least level of Cd was found in USB and SC (0.05 ± 0.0 and 0.07 ± 0.02 µg/g respectively). Statistical analysis reveals that the difference in the level of Cd between USC, SB and USB, SC are signi cant (P < 0.05) whereas the difference between USC and SB and USB and SC is insigni cant (P > 0.05). Among the four samples, the USB registered with the highest level of Cu (148.00 ± 1.71 µg/g) followed by the SB (117.94 ± 11.02 µg/g), while the samples USC and SC registered a low level of Cu (63.78 ± 3.45 and 65.18 ± 3.95 µg/g respectively). The level of iron (Fe) was found to be high in the USB (232.88 ± 13.16 µg/g), followed by SB (203.82 ± 12.34 µg/g). The samples USC and SC registered almost similar value (165.33 ± 3.45 and 161.49 ± 4.61µg/g respectively). The statistical analysis revealed that the difference between the butts and cigarettes is signi cant (P < 0.05), but an insigni cant difference was observed between the samples USC and SC. The level of lead (Pb) was found to be highest in USB (15.84 ± 2.37µg/g), followed by SB and SC (13.69 ± 1.67 and 8.90 ± 1.66 µg/g respectively) and least in USC (5.77 ± 1.33µg/g). The statistical analysis on the level of Pb between the samples was signi cant (P < 0.05). The Sn was found to be undetectable or absent in all the samples. The level of zinc (Zn) was found to be high in USB and SB (39.37 ± 3.43 and 40.93 ± 2.00 µg/g) while the least level of Zn was found in USC and SC (29.36 ± 3.03 and 31.89 ± 3.44µg/g). Statistical analysis revealed a signi cant difference between butts and cigarettes (P < 0.05) whereas the difference between USB, SB and USC, SC showed insigni cant difference (P > 0.05). The levels of Hg was found to be high in USB (205.11 ± 9.62 µg/g), followed by SB and USC (141.25 ± 6.23 and 101.34 ± 4.57 µg/g respectively). The least level of Hg was found to be in SC (76.66 ± 0.74 µg/g). Statistical analysis revealed that there is a signi cant difference between the different samples (Fig. 5).

Levels of heavy metals in the leachates of different samples of expensive brand
The levels of Cd was found to be high in USB (0.38 ± 0.01 µg/g), followed by USC (0.11 ± 0.0 µg/g). The values of Cd present in SB and SC were found to be the same. (0.02 ± 0.0 and 0.02 ± 0.02 µg/g respectively). The statistical analysis of Cd reveals that there was a signi cant difference between the levels of USB, USC and the other samples (P < 0.05). The levels of Cd was found to be insigni cant between the samples SB and SC (P > 0.05). Among the four samples, USB registered with the highest level of Cu (40.15 ± 1.83 µg/g) and the least amount was found in SC (13.45 ± 11.09 µg/g). The samples of USC and SB registered with almost similar values. (24.57 ± 3.25, 23.16 ± 2.15 µg/g respectively). Statistical analysis reveals that there is a signi cant difference between USB and SC (P < 0.05), whereas the levels of Cu between USC and SB is insigni cant (P > 0.05). The level of iron (Fe) was found to be high in USB and SB (125.75 ± 9.01, 117.66 ± 3.46 µg/g respectively), followed by USC (73.62 ± 0.50 µg/g). The least level of Fe was found to be in SC (17.55 ± 13.20 µg/g). Statistical analysis reveals that there is a signi cant difference between butts and cigarettes (P < 0.05). The levels of Fe between USB and SB was found to be insigni cant (P > 0.05), whereas there is a signi cant difference between levels of Fe between USC and SC (P < 0.05). The level of lead (Pb) was found to be highest in USB (29.25 ± 3.51 µg/g), followed by SB, USC and SC (6.38 ± 1.08 and 5.51 ± 0.41 and 2.18 ± 1.50 µg/g respectively). Statistical analysis reveals that there is a signi cant difference among all four samples (P < 0.05). The level of Sn was found to be below the detectable level in all four samples. Among the four samples, a high level of Zn was found to be in USB and SB (31.87 ± 0.54 and 33.0 ± 2.12 µg/g respectively), whereas the samples USC and SC registered with low level of Zn (17.29 ± 0.19 and 11.30 ± 7.99 µg/g respectively) Statistical analysis reveals that there is a signi cant difference in levels of Zn between the butts and cigarettes (P < 0.05), whereas the difference between the sample was found to be insigni cant between USB and SB; and USC and SC (P > 0.05) (Fig. 6).

Levels of heavy metals in the leachates of different samples of the moderate brand
The level of Cd was found to be high in the sample USB (0.89 ± 0.02 µg/g), followed by SC (0.12 ± 0.02 µg/g). The samples USC and SB had the same level of Cd (0.05 ± 0.0 µg/g). Statistical analysis reveals that the difference in the level of Cd between USB and SC are signi cant (P < 0.05). Among the four samples, the USB registered with the highest level of Cu (89.15 ± 3.79µg/g) followed by the USC (25.85 ± 1.08µg/g), while the samples SC and SB registered a low level of Cu (11.69 ± 0.73 and 11.13 ± 0.26 µg/g respectively). The level of iron (Fe) was found to be high in SB and USB (246.37 ± 2.99, 242.81 ± 10.59 µg/g respectively), followed by USC (124.58 ± 5.81 µg/g). The least level of Cu was found in SC (105.11 ± 3.45 µg/g). The statistical analysis revealed an insigni cant difference between the samples SB and USB (P > 0.05) and a signi cant difference is seen in the level of Cu between the butts and cigarettes (P < 0.05). The level of lead (Pb) was found to be highest in USB (128.89 ± 8.53µg/g), followed by SC and SB (21.25 ± 1.32 and 16.29 ± 0.48 µg/g respectively). The least level of Pb was observed in USC (5.88 ± 0.36µg/g). The statistical analysis on the level of Pb between the samples was signi cant. The level of tin (Sn) showed the highest trend in USC (3.64 ± 0.55 µg/g). The level of Sn was below detectable range in the samples USB, SB and SC. The level of zinc (Zn) was found to be high in USB (64.00 ± 9.28µg/g), followed by SB (40.96 ± 0.54 µg/g). The level of Zn was similar for the samples USC and SC (27.74 ± 1.14 and 25.95 ± 1.36 µg/g respectively) Statistical analysis of the levels of Zn showed a signi cant difference between butts and cigarettes and between USB and SB too (P < 0.05) whereas there was no signi cant difference between USC and SC (P > 0.05) (Fig. 7).

Levels of heavy metals in the leachates of different samples of cheap brand
The level of Cd was found to be similar in all the three samples USB, SB, and SC, but reduced signi cantly in USC. The statistical analysis reveals that there is an insigni cant difference among the samples USB, SB, and SC the levels of Cd in the four samples (P > 0.05). Among the four samples, the USB registered with the highest level of Cu (89.76 ± 0.08 µg/g), followed by SC and USC (12.05 ± 0.47 and 10.29 ± 0.50 µg/g respectively). In the sample SB, the level of Cu was below the detectable level. The statistical analysis reveals that there is a signi cant difference between butts and cigarettes. The samples SC and USC showed an insigni cant difference in the levels of Cu. The level of iron (Fe) was found to be high in the USB (769.36 ± 17.02µg/g), followed by USC and SB (191.47 ± 8.41 and 107.62 ± 0.80 µg/g respectively). The least level of Fe was found to be in SC (66.47 ± 2.12 µg/g). Statistical analysis reveals that there is a signi cant difference in the level of Fe between all four samples. The level of lead (Pb) was found to be highest in SC (18.06 ± 1.41µg/g), followed by USB and USC (9.68 ± 0.66 and 2.61 ± 0.29 µg/g respectively). The least level of Pb was found to be in SB (0.83 ± 0.80 µg/g) statistical analysis reveals that is there is a signi cant difference between all the four samples (P < 0.05). Among the four samples, USB and SB registered a high level of Sn (168.60 ± 9.40, 153.93 ± 7.02 µg/g respectively), whereas the level of USC and SC was found to contain a lower level of Sn (106.60 ± 2.50 and 103.16 ± 0.68 µg/g respectively). Statistically, there is a signi cant difference between butts and cigarettes. The level of Sn between the samples USB and SB: USC and SC were found to be insigni cant (P > 0.05) (Fig. 8).

Discussion
Cigarettes are found to be littered in all places and are become a serious threat to the environment. In the present study, efforts were taken to determine the level of different heavy metals present in popular cigarette brands, that are sold in Bengaluru city, South India and the number of heavy metals leached out into the aquatic medium. For this purpose, popular tobacco cigarette brands were used. Cadmium, Copper, Tin, Lead, Iron, Mercury and Zinc present in the samples was analyzed.
Cigarette litter, both smoked cigarette and butt, thrown into the environment encompass a wide range of cigarette brands with varying amounts of tobacco left on the lters. In this study, smoked cigarette material and butts were collected due to their popularity and use to provide a sample population representative of the local cigarette litter concerning the brand and amount of remnant tobacco, but the metal concentrations in cigarettes may vary among the brands. The relative percentage of the mean value with a standard deviation of heavy metal present and leached is relatively low for most sample sets, demonstrating the reproducibility of this method. The leaching procedure employed in this preliminary study is not an open system to mimic the natural environment, but a closed system is the most straightforward method of obtaining the maximum amount of leachable metal. Another disadvantage of this study is lacking information on the interactions of various other physicochemical parameters such as pH, temperature etc.
Among the samples analyzed, the mean of lead (Pb) was found to be highest in the present study compared with previous studies. The mean amount was found to be 16.85 µg/g with a minimum amount of 0.834 µg/g and a maximum of 128.893 µg/g and the amount was found to be more in the leachates of the cigarette sample. This was much higher than other reports (Janaydeh et al. 2019;Engida and Chandravanshi 2017;Sebiawu et al. 2014;Ashraf, 2012;Kazi et al. 2009;Raju et al. 1999). In the present study, a mean of 78.98 µg/g of copper with a maximum of 287.52 µg/g was observed and this level was several folds higher than other reports (Dobaradaran et al. 2017;Engida and Chandravanshi 2017;Sebiawu et al. 2014;Raju et al. 1999). Similar results were observed with Hg (Phal 2011;Kowalski and Wierciński 2009;Raju et al. 1999). Whereas the Fe (Dobaradaran et al. 2017;Engida and Chandravanshi 2017;Sebiawu et al. 2014;Raju et al. 1999), Cd (Dobaradaran et al. 2017;Janaydeh et al. 2019;Engida and Chandravanshi 2017;Sebiawu et al. 2014;Ashraf 2012;Eneji et al. 2013;Kazi et al. 2009;Raju et al. 1999) content reported in the present was comparatively lesser. This may be due to the difference in leaching methods employed and the number of samples used.
Leachates of unsmoked cigarettes and butts were investigated in the present study to provide concentrations of the metals of interest leached out into the environment and to identify possible instances of contamination. In general, the metal concentrations of the leachates prepared from the butt were higher than those present in the leachates prepared from cigarettes. This difference may be due to the loss of heavy metals in smoke or ash during cigarette combustion (Zul qar et al. 2006;Benner et al. 1989). But Hg and Sn were not present in the leachate, whereas the presence of these metals could be observed in the direct samples (without leaching). This may be due to not leaching these heavy metals in 24hrs. If the butts kept more days in the water, then they may leach. For local aquatic organisms sensitive to Pb, Cd and Zn, a rapid release of these metals may have implications for acute biological effects.
The results of this study also revealed that concentrations of metals were higher in general leached from unsmoked cigarettes than smoked cigarette materials implies that cigarette litter with more remnant tobacco likely causes greater contamination than butts with little or no remnant tobacco. This result calls into question a practice of some environmentally conscious smokers, who scatter remnant tobacco into the environment but keep the lter until it can be deposited into a waste container.

Conclusions
We have compared the level of heavy metal present and leached from both cigarette and butt into the aquatic ecosystem. The results revealed that the butt of both smoked and unsmoked samples (SB and USB) contains more heavy metals compared to the tobacco part of a cigarette and releasing a relatively higher concentration of heavy metals in the aquatic ecosystem. Furthermore, the apparent rapid leaching of heavy metals from littered cigarette and butts samples increases the potential for acute toxicity to aquatic life. Hence, further studies are highly warranted to assess the effect of heavy metal leached from the littered cigarette butts on aquatic life and the environment in general. Figure 2 Arti cial smoking of cigarettes    MariaetalTableEnvironProcess.xlsx