Shell Lime Research Articles

Influence of age of fermented Terminalia chebula fruit extract in shell lime: An ancient lime putty production technique adopted in Indian heritage structures

The study examines the influence of fermentation age of 5% w/v extract (K5%) of Terminalia chebula fruit in shell lime, using a 0.75 K5%-to-binder ratio. The carbon dioxide evolution, UV-Spectrometric analysis of K5% followed by Gas chromatography and mass spectroscopy (GC-MS) of the slaked putty variants, identified the predominance of organic acids, fatty acids, and esters. The 90th day physical, mechanical, and durability testing confirmed the lowest water-accessible porosity at 31.07 ±0.11% v/v in K5%-4-90, with capillary porosity trending as K5%-4-90<K5%-7-90<K5%-14-90<R-90<K5%-1-90, affecting compressive strength. Mineralogical and morphological studies confirmed the formation of calcite (CaCO3) polymorphs and calcium oxalates via the oxalate-carbonate pathway. Further, thermogravimetric analysis (TGA) revealed the highest %CaCO3 in K5-4-90 and K5-7-90 samples, linked to carbonation extent. The study specifies that K5% at the 4th and 7th days of fermentation age significantly alters putty characteristics, supporting its widespread application and internal and external finishes in heritage structures.

Decoding of lime-based binder materials of ancient vernacular Chettinad constructions in Southern India through microanalytical characterization

Vernacular Chettinad lime binder is widely popular in Southern India because of its quality in terms of durability over centuries and the fine glossy finishes attainable. However, its manufacturing technique concerning raw materials, the application process, and resultant characteristics are not explored or documented. The present study attempts to explore the mix compositions and application strategies of Chettinad lime plaster and mortar by characterizing samples collected from two ancient structures approximately 100 years old and in intact condition. Like any Chettinad constructions, the plaster in both buildings constitutes a base coat (coarser as observed) and a superior smooth glossy appearance finishing layer. The plaster samples collected from various locations from the two sites were thoroughly characterized for their physicochemical properties, microstructural characteristics, surface properties, mineralogical compositions, porosity, and pore size distribution. Analyses of the plaster samples suggest that the air lime and locally available, river-based siliceous aggregates were utilized as binder and aggregate, respectively, in ratios ranging from 1:1.51 and 1:2.57 in each of the buildings studied and correlated the ratio to their durability performance as well. Shell lime and organics such as curd and egg white were utilized to obtain the glossy plaster finish. The art of manufacturing and application of such a durable indigenous binder system is lost, not continued, and undocumented. The present study would act as (i) documentation that aids the continuation of the technique of the traditional binder production, as well as (ii) decoding the compositional differences of the plaster and mortar at various locations/applications, which would help in properly maintaining and restoring degraded portions of building structures by reproducing similar and compatible material.

Seashells to lime: swotting of a vernacular method and needs for revival

Lime is the versatile mineral. Various forms of lime are used in environmental, metallurgical, construction, chemical/industrial applications, and more. It has been used for masonry mortars and plastering for centuries. Lime is usually obtained from lime stone. Places like Kerala where lime stone is scarce, lime is majorly obtained from seashells so they developed their own traditional method to extract lime. Shell lime was one of the major components in construction of most of the houses, temples, bridges, dams etc. in Kerala during the earlier days. People used shell lime not only as a replacement to cement but also as a plastering agent which helps to reduce temperature in the interiors. This dissertation is retrospection into the vernacular method of making lime mortar from seashells by visiting the workspace. The study also intends to analyse the challenges faced by this method and provide with necessary recommendations.

Development of soil-less substrates capable of degrading organic nitrogen into nitrate as in natural soils

Soil-less substrates are unable to catalyse nitrification because the addition of a high concentration of organic substances suppresses nitrification. We used a previously developed multiple parallel mineralization method, which enables the use of organic fertilizers in hydroponics, to support nitrification in soil-less substrates. In this method, microorganisms immobilized on porous substrates produced inorganic nitrate from organic substances, as in a natural soil. Phosphate and potassium ions were also released. Microorganisms produced nitrate from organic substances when immobilized on polyurethane resin, rockwool, vermiculite, oyster shell lime, and rice husk charcoal. The optimal amount of organic substance added daily to 100 mL of substrate held 6 mg of organic N. The optimal incubation temperature ranged from 25 to 42 °C. A high relative humidity (51% or higher) was more suitable than drier conditions (20%). The optimal amount of fish fertilizer added to the substrate was 6 mg organic N. The lower the C/N ratio of the organic substance, the better the result. Vegetable plants grew well on inoculated substrates but not on uninoculated substrates. These results show that soil-less substrates can be used to create artificial soils in which plants can be grown with the addition of organic fertilizer, as in a natural soil.

Correction of soil acidity with shell lime and dolomitic limestone in a Latossolo Vermelho distrófico in Paraná state, Brazil

Soil acidity is a limiting factor for agricultural production, and the correction is carried out by liming, with the variable response with characteristics of the soil and the source used. The study aimed to analyze the effect of liming on a Latossolo Vermelho distrófico (stands for the oxisols in soil taxonomy and Ferralsols in WRB-FAO). The experiment was conducted in a completely randomized design in a 2x2x3 factorial scheme, with two soil textures (medium and clayey), two types of limestone (dolomitic and shell), and three soil cover conditions (without cover, with corn residues, and with soy residues). Liming carried out considering the chemical characteristics of the soil, the neutralization power of the sources, and the quantity determined by the base saturation method. The data were submitted to analyses of variance, and the means were compared by the Scott-Knott test, with 5% significance. The acidity correction occurred in less time in clayey soil. The coverage on the soil surface influenced the acidity correction, with a dynamic response concerning the analyzed conditions. Shell and dolomitic lime showed adequate efficiency in correcting acidity in both soil textures, with non-standard differences in conditions.

STRUCTURAL CONCRETE MODIFIED WITH SCALLOP SHELL LIME

This research was conducted to determine the effect of the scallop shell lime (SSL) on the compressive strength of concrete made with Portland cement type Ico and natural aggregates from a quarry, where SSL was added at 3%, 4% and 5%. The physical and mechanical characteristics of the aggregates were determined based on the N.T.P. 400.037/ASTM C22 standard, and the mix design was carried out through the ACI method. The SSL was used due to the high calcium content present in the valve. Standard concrete controls were prepared and cured by adding 3%, 4% and 5% SSL (339.0183/ASTM C192M), which were analyzed at 7, 14 and 28 days of curing. The results showed that the compressive strength at 28 days was 242.63 kg/cm2 when 3% SSL was added, increasing with respect to the standard control by 16%. With the addition of 4% SSL, the maximum strength reached was 245.25 kg/cm2, and with 5%, the compressive strength reached was 261.17 kg/cm2, increasing by 24%. In conclusion, the SSL positively affects the increase of concrete strength, and the percentage with the highest incidence is 5%.

Characterization study on the influence of limestone and shell lime as a fine aggregate substitute: A traditional approach on lime plaster restoration

The present scenario on the rapid globalization and industrial use of natural resources across the globe has made this investigation to benefit on the utilization of crushed limestone (LSM) and shell lime (SLM) as aggregate substitutes to conventional lime mortar. Physio-chemical and modern analytical methods like XRD, TGA, FT-IR and strength test were performed, evaluating the performance of mortars with modern substitutes. Carbonate polymorphs such as calcite, vaterite & aragonite were majorly depicted in all the mortars. XRD reveals the high ranged CSH formation in limestone and shell lime mortar for 28 & 56 days. FT-IR results indicated the presence of high range calcite peaks and increased portlandite peaks at 3640 cm−1 for shell lime and limestone mortar on 56 days respectively. TGA concluded with high decarbonation occurred at 750–760 °C for shell lime & limestone mortar. The mechanical strength of LSM has peaked up to 1.58 and 1.77 MPa along with gradual strength gain around 1.54 and 1.57 MPa for SLM mix with 0.98 & 1.55 MPa for conventional mortar for 28 and 56 days respectively. Modified Limestone mortar revealed the enhanced strength up to 11.2% on natural carbonation.

Amelioration of acidity and iron toxicity in lateritic lowland rice soil using non-conventional sources of calcium

A field experiment was conducted to evaluate the effectiveness of non conventional sources of calcium like phosphogypsum, limestone powder and their blends in managing soil acidity and iron toxicity and enhancing the yield of rice in comparison to conventional shell lime. The results revealed that all the liming treatments significantly reduced the soil acidity and iron toxicity problem in rice field. The soil pH was increased from 4.61 in control to 5.33 in the treatment receiving shell lime@ 600 kg ha -1. The exchangeable calcium content in soil increased from 749 mg kg -1 in control to 909 mg kg -1 in phosphogypsum applied treatment. The 0.1 N HCl extractable iron content in soil was reduced from 511 mg kg -1 in control to 353 mg kg -1 in lime stone powder 300 kg ha -1 + phosphogypsum 300 kg ha -1 applied treatment. The availability of N(295.8 kg ha-1,K (1 06.8 kg ha-1), Mg (58.2 mg kg -1), S (31.65 mg kg -1), Zn(4.19 mg kg -1), Cu (3.79 mg kg -1) and B (0.26 mg kg -1) were the highest in treatment receiving lime stone powder 300 kg ha -1 + phosphogypsum 300 kg ha -1 whereas P (97.35 kg ha -1) was the highest in treatment receiving shell lime@ 600 kg / ha. The available Mn and exchangeable Al were found to decrease with the application of liming materials.The uptake of nutrients, growth and yield parameters of rice were significantly increased due to the influence of liming treatments. The highest grain yield of rice (5.73 t ha-1) was obtained in the combined application of lime stone powder 300 kg ha -1 + phosphogypsum 300 kg ha -1.

Experimental study on factors affecting the physical and mechanical properties of shell lime mortar

Shell lime is an building material widely used in ancient buildings in Chinese coastal areas, yet the relationship among the constituents and mechanical properties of shell lime remains poorly understood. This paper aims to study the factors that influence the properties of shell lime mortar. Laboratory tests were conducted on shell lime samples to investigate the properties of shell lime mortar and the influences of the water-lime ratio, sand-lime ratio, curing ages, and the addition of glutinous rice. The results show that the hydraulic component β-CS can be generated in shell lime calcined in the laboratory. The sand-lime and water-lime ratios have major impacts on the disintegration index, shear strength and compressive strength of shell lime mortar, which can also be enhanced by adding glutinous rice.

Investigation and modification of two kinds of Chinese traditional lime in cultural building relics

Abstract As the earliest cementing materials, lime, divided into aerial lime and hydraulic lime according to reaction mechanism, has been widely applied to heritages. Previous studies revealed that hydraulic lime mortars satisfy the conservation principles and high early strength demands of conservation because they have better mechanic strength and higher environmental adaptability than aerial lime. In this research, Chinese traditional hydraulic lime (ginger nut, AGA clay and shell lime) were modified and designed to restore San-he Tu buildings (composing of clay, sands and aerial lime). The result reveal that modified ginger nut showed optimal mechanic properties and weather resistance abilities than other lime mortars, and it is possibly due to the structure between aggregates and hydration or carbonation products. Conservation application using modified ginger nut mortar on the restoration of cracks were carried out and the restoration effect was discussed in detail. The conservation results indicated that the Chinese traditional hydraulic lime mortars are proper to restoring limes in ancient buildings.

Development of Self Compacting Concrete with Various Mineral Admixtures

Self- Compacting concrete (SCC) is a special type of concrete that is able to flow and compact under its own weight and can occupy all the spaces in the form without any vibration effect, and at the same time cohesive enough to be handled without bleeding or segregation. The required compaction properties are achieved by adding super-plasticizers and mineral admixtures such as fly ash, rice husk ash, silica fume, etc. The utilization of these treated industrial by-products as cement replacement will not only help to achieve an economical SCC mix, but it is envisaged that it may improve the microstructure and consequently the durability of concrete. This provides solution to disposal problems and other environmental pollution issues created by these otherwise waste products. This paper presents the results of an experimental study aimed at producing SCC mixes of M25 grade by using the Modified Nan Su method, incorporating five mineral admixtures, viz., Fly Ash, Blast Furnace Slag (GGBS), Silica Fumes, Rice Husk Ash, and Shell Lime powder as supplementary cementing materials. Also, this paper gives the comparison of these SCC mixes in terms of their properties like compressive, split tensile, and flexural strengths. The fresh concrete properties are also included in the study.

패화석이 보리생육과 토양 미생물상에 미치는 영향

산성토양을 개량하기 위한 목적으로 패화석을 시용하여 보리의 생육, 수량과 품질 및 토양 미생물상을 조사하였다. 패화석 처리로 석회고토나 무처리에 비해 <TEX>$m^2$</TEX>당 수수와 천립 중이 높아져 보리의 수량은 석회소요량 처리구인 패화석 <TEX>$3.09Mg\;ha^{-1}$</TEX> 시용에서 <TEX>$5.53Mg\;ha^{-1}$</TEX>로 가장 많았으며 석회고토 동량의 패화석 처리구도 <TEX>$5.23Mg\;ha^{-1}$</TEX>로 석회고토 <TEX>$5.20Mg\;ha^{-1}$</TEX> 보다 증대되었다. 패화석 처리구는 석회고토 처리구 보다 보리 단백질 함량은 0.5~0.7% 낮아져 농산물의 품질향상에 미치는 영향은 석회고토보다 양호한 것으로 판단되었다. 토양 pH는 패화석과 석회고토 시용으로 무처리 보다 0.5~0.6 정도 상승되었고 치환성 Ca 함량은 패화석 <TEX>$3.09Mg\;ha^{-1}$</TEX> 처리구에서 <TEX>$7.5cmol_c\;kg^{-1}$</TEX>으로 가장 높았으며 석회고토 처리구는 치환성 Mg 함량이 <TEX>$2.5cmol_c\;kg^{-1}$</TEX>으로 가장 높게 나타났다. 패화석 <TEX>$3.09Mg\;ha^{-1}$</TEX> 및 <TEX>$2.38Mg\;ha^{-1}$</TEX> 처리구는 석회고토 <TEX>$2.38Mg\;ha^{-1}$</TEX> 처리구에 비해 토양의 세균 밀도는 각각 60.9 및 <TEX>$69.7{\times}10^6CFU\;g^{-1}$</TEX>로서 높은 반면 방선균 밀도는 각각 32.4, <TEX>$45.4{\times}10^5CFU\;g^{-1}$</TEX>로서 낮았다. Oyster shell has a high content of <TEX>$CaCO_3$</TEX> to be used as a acidic soil amendment. To enhance productivity of barley and soil microbe in an upland soil, oyster shell and calcium-magnesium carbonate were selected as a soil amendments in this study. A field experiment was treated no treatment (hereafter, control), oyster shell lime <TEX>$3.09Mg\;ha^{-1}$</TEX> and <TEX>$2.38Mg\;ha^{-1}$</TEX>, and calcium-magnesium carbonate <TEX>$2.38Mg\;ha^{-1}$</TEX> as amount of lime requirement in silt loam soil. The yield of barley from the oyster shell lime treatment was the highest. The protein content of barley was the highest of 11.1% in the calcium-magnesium carbonate, followed by 10.7% for the control, 10.6% for the oyster shell lime <TEX>$3.09Mg\;ha^{-1}$</TEX>, and 10.4% for the oyster shell lime <TEX>$2.38Mg\;ha^{-1}$</TEX>. Soil pH value was higher than that of control in harvesting stage. In addition, the population of soil bacteria was highest in oyster shell lime <TEX>$2.38Mg\;ha^{-1}$</TEX>, actinomycetes was highest in calcium-magnesium <TEX>$2.38Mg\;ha^{-1}$</TEX>. We concluded that the oyster shell lime can be effective to restore soil nutrient and microbe balance in an upland soil.

PIXE study on Thai amulet: Phra Somdej Wat Rakhang

Phra Somdej Wat Rakhang amulets which were one of the most famous Thai amulets created in an image of Lord Buddha meditation. They were made to explain the Dharma of Buddha and to bless every life in this world for good karma. Their compositions contained with both inorganic and organic materials such as shell lime, assorted flowers, ashes from incense urns, etc. Various molds were differed both types and compositions. In this work, it was the first time on advanced structural analysis using non-destructive x-ray fluorescence spectrometry methods; particle induced x-ray emission. Samples were selected by various molds to analyze theirs composition. Results revealed the presence of Ca, Al, K, Si and others such as Fe, Cu, Mn and Zn. It was also found that there were differences in concentration of composition. It can be concluded that their matrices were heterogeneous. Each mold may be characterized using the differences in its composition.

Nutrient composition of leaves and fruit juice of grapevine as affected by soil and nitrogen fertilization

AbstractEffects of soil type and nitrogen (N) fertilizer–application rates on the nutrient composition of grapevine (Vitis vinifera L. cv. Riesling) leaves during a growing cycle were compared with the composition of the resulting grape juice. Grapevines were planted in 75 L containers that had been installed in a vineyard and filled with three different vineyard soils (loess, shell lime, and Keuper). Four typical levels of N fertilizer (40, 80, 120, and 160 kg N ha–1) were applied. Elemental composition of mature leaves sampled seven times during the growing cycle as well as of the extracted grape juice was analyzed. The time of sampling affected all measured elements (C, N, Ca, K, P, Mg, S, Fe, Zn, Mn, and B) in the leaves. Nitrogen‐fertilizer rate affected the concentrations of all elements except Ca and Mg, while the soil type had significant effects on elemental composition of the leaves with the exception of N, B, and Ca. Soil type had a significant effect on K, S, Mn, and B in the grape juice. Increasing rates of N fertilizer increased C concentration in the grape juice significantly and affected its elemental composition similar to the effects in leaves. This may be explained with the role of leaves as the source for supplying the grapes during ripening via phloem transport. Cluster analysis for the elemental composition of soils, leaves, and grape juice revealed no consistent relationships indicating that other soil characteristics in addition to the mineral concentration influence the elemental composition of grapevine leaves and grape juice.

큰느타리(Pleurotus eryngii)의 인공재배에 관한 연구

큰느타리버섯의 인공재배기술을 확립하기 위하여 균사 생장이나 자실체 생장에 필요한 영양원과 수분 및 산소를 공급하는 최적 배지, 수확량과 품질 및 경영 효율을 좌우하는 최적 재배용기, 적정한 배양기간, 그리고 최적의 발이방법 등을 검토하였다. 배지의 주재료로서 톱밥 단일배지보다 톱밥+콘코프의 혼합배지에서 배양기간은 다소 지연되었으나 수확량과 품질이 좋았다. 톱밥과 콘코프의 배합비는 75 : 25(v/v)가 가장 좋았다. 배지 주재료로서 비트펄프의 배합은 균사생장이 저하되고 수확량도 감소되어 바람직하지 않았다. 배지 제조시 영양제로 미강과 밀기울 그리고 면실박을 각각 12 : 12 : 6(v/v)으로 혼합하면 수확량이 가장 많아 효과적이었고, 밀기울과 면실박을 각각 15% 혼합한 처리구는 수확량이 가장 낮았다. 배지 첨가제인 제오라이트, 패분과 건비지의 첨가는 유의한 효과가 없었다. 큰느타리 병재배시 polypropylene(PP) 병의 병구 직경이 크면 발이수는 많으나 유효갯수는 유의하게 증가하지 않았다. PP병의 용량이 클수록 수확량과 품질이 양호하였고 용량 1100 ml-병구직경 <TEX>${\phi}75\;mm$</TEX>가 가장 양호하였다. 큰느타리버섯의 봉지재배시 투명 사각봉지에서 균긁기하지 않는 전면(全面)발생재배는 PP병재배보다 재배면적당 수확량이 다소 높게 나타났다. 발이상태는 <TEX>$24{\sim}42$</TEX>일간의 배양기간에 따른 차이가 없었으나, 배양기간이 짧으면 갓 형성과 수확량이 불량하였다. 적정배양기간은 <TEX>$22{\pm}2^{\circ}C$</TEX>배양시 약 35일 정도이었다. 균긁기 후 무피복 정치, 피복 정치 및 도치법의 발이방법 중 도치법이 과습방지와 낙하균의 오염방지로 가장 양호하였다. This study was carried out to investigate the artificial cultivation of Pleurotus eryngii on the optimal medium vessel, periods of cultivation and the optimal method of pinheading for both yield and quality of fruiting body were also performed. The optimal composition of sawdust medium in polypropylene(PP) bottle was combination of sawdust(70%) and corncob(30%) but increased amount of corncob delayed the period of mycelial growth. The mycelial growth and the yield of fruiting body in the medium with beat pulp were worse than that without beat pulp. The optimal composition of nutrients for both yield and quality of fruit body tuned out to be a combination of rice bran(12%), wheat bran(12%) and cottonseed cake(6%). Additions of zeolite, shell lime and bean curd dregs were not effective in mycelial growth and yield of fruit body. When testing size of PP bottle for cultivation, the larger of bottle mouth is, the more pinheading number found, but the number of available fruit body is not significantly different. The culture in <TEX>$1100\;ml-{\phi}75\;mm$</TEX> bottle is the best in the yield and quality of fruit body than those in <TEX>$555\;ml-{\phi}50\;mm,\;850\;ml-{\phi}58\;mm,\;850\;ml-{\phi}65\;mm\;and\;1100\;ml-{\phi}65\;mm$</TEX> bottle. Using the PP bag for cultivation, a square shaped bag was better than a round shaped and black square shaped in mycelial growth and yield of fruit body. The most suitable period of incubation was 35 days after inoculation at <TEX>$22{\pm}2^{\circ}C$</TEX>. When the incubation periods was decreased less than 35 days, the pileus formation and yields were very bad but a pinheading condition looked similar, For an optimal pinheading, turning upside down was better than standing and covering.

Stilt-Root Subsistence: Colonial Mangroves and Brazil’s Landless Poor

Stilt-Root Subsistence: Colonial Mangroves and Brazil’s Landless Poor

The Chemical Composition of Xylem Sap inVitis viniferaL. cv. Riesling During Vegetative Growth on Three Different Franconian Vineyard Soils and as Influenced by Nitrogen Fertilizer

Cuttings of grapevine (<i>Vitis vinifera</i> L. cv. Riesling clone B 68) grafted on SO4 (Selection Oppenheim No. 4) rootstocks were grown in pots with three different soils from Franconian vineyards derived from different geological formations (namely, Loess, Muschelkalk (shell lime), or Keuper). Additionally, the influence of N-fertilizer treatment was investigated. From the midrib of leaves six to eight of the sole shoot, xylem sap was collected simultaneously by pressurizing the rhizosphere during the vegetative growth phase. The chemical composition of xylem sap was determined and compared with that of the aqueous soil extract. In Muschelkalk soil, carbon, nitrogen, and calcium were present in the greatest concentrations. Sulfur, boron, magnesium, sodium, and potassium were greatest in Keuper, and the concentrations in Loess soil were intermediate. Aqueous extraction of the soils resulted in a two-fold greater concentration of total solutes in Keuper extract compared with Muschelkalk, and more than threefold than in Loess. The apparent volume flow was greatest in the middle leaves along the shoot and in plants grown on Keuper; additionally there was a tendency for fertilizer treatment to increase flow. The concentrations of mineral ions in xylem sap were the same in all the leaves of a shoot of grapevine. An important exception was the supply to the leaves of amino acids, which increased in concentration along the transpiration stream and were greatest in the youngest leaves (particularly in non-fertilized plants). Potassium was the dominant cation in xylem sap and was greatest in plants grown on Keuper. Concentrations of sodium and calcium were increased in non-fertilized plants, but not significantly in vines grown on Muschelkalk. In xylem sap, nitrate was the major anion, followed by malate. Nitrate concentration was greatest in plants grown on Muschelkalk, while malate was greater in plants grown on Keuper. Chloride, sulfate, and phosphate concentration in sap were increased by fertilizer treatment. Abscisic acid was markedly increased in xylem sap of non-fertilized plants grown on Loess and Muschelkalk and was discussed as a signal for nutrient limitation. If Keuper was the substrate it was also increased by fertilizer treatment. Of the organic N-compounds, glutamine was the largest fraction. On the basis of the relation of nitrate to total N in xylem sap, it could be assumed that about 40% to 75% of nitrate reduction took place in the shoots. In general, soil type had only a moderate effect on the chemical composition of the xylem sap compared with the effect of N-fertilizer.

Mapping Pattlerns of Cracking and Moisture Migration in Early Brickwork and Replicating Shell Lime Mortar

This paper reports three aspects of an ongoing building archeology project at the MacPheadris-Warner House (ca. 1716–23) in Portsmouth, N.H., U.S.A. One is the use of a portable moisture meter to map rising damp levels and areas of water infiltration through brickwork. The second is the mapping of crack patterns and other defects on exterior elevations. We will also refer to a second site, the Juliette Gordon Low House in Savannah, Georgia, in discussing the problem of crack mapping. The third project is an ongoing attempt to replicate a shell lime mortar.

Changes in vitamin A conditioned hamster cheek pouch epithelium on exposure to commercial shell lime (calcium hydroxide) and tobacco I — Optical histopathology

Epidemiologically a high incidence of oral cancer and addiction to tobacco, singly or in combination with other ingredients of the betel quid, are closely correlated. Attempts at the induction of malignancy in laboratory animals on exposure to these ingredients have hitherto failed. Studies are reported on cheek pouch epithelium of 152 Syrian golden hamsters exposed to commercial shell lime (calcium hydroxide) and tobacco, singly and in combination, with parallel conditioning by Vitamin A palmitate. The abnormal changes found especially in lime and lime-plus-tobacco treated epithelia are massive hyperplasia, keratinization anomalies, marked edema and dysplasia. The most significant findings are (1) greater epithelial alteration caused by lime, lime plus vitamin A, tobacco plus vitamin A, lime plus tobacco and lime plus tobacco and vitamin A, than by tobacco alone; (2) increasing epithelial dysplasia in response to longer periods of exposure to the test substances; and (3) enhancement of tissue changes in the presence of vitamin A.