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PubMed2006

Ultrasonic effects on titanium tanning of leather.

The effects of ultrasound on titanium tanning of leather were investigated. Either 20 or 40 kHz ultrasound was applied to the titanium tanning of pigskins. Five different treatment conditions were carried out and the effects were examined, such as leather shrinkage temperature (T(s)), titanium content and titanium distribution in the leather. Overall heat loading was carefully controlled. Results showed that 20 kHz ultrasound effectively improves titanium agent penetration into the hide and increases the leather's shrinkage temperature. Doubling the frequency to 40 kHz produced negligible enhancements. An impressive 105.6 degrees C T(s) was achieved using 20 kHz ultrasound pretreatment of the tanning liquor followed by 20 kHz ultrasound in the tanning mixture (liquor plus pigskins) in a special salt-free medium. Finally, using a unique ultrasonic tanning drum with 26.5 kHz ultrasound, the T(s) reached a record level of 106.5 degrees C, a value not achieved in conventional (no ultrasound) titanium tanning. The ultrasonic effects on titanium tanning of leather are judged to make a superior mineral tanned leather.

Journal Article↗

PubMed2000

Effects of Psoroptes ovis infection and its control with an ivermectin controlled-release capsule on growing sheep. 2. Evaluation of wool production and leather value.

To evaluate the prophylactic and therapeutic effects of an ivermectin controlled-release capsule (IVM-CRC) on the productivity of growing sheep infested with Psoroptes ovis 24 male and 24 female Merino landrace lambs, 5-6 months old and weighing 21.2-35.0 kg, were used. Sixteen replicates of three animals were formed based on sex and Day 0 body weight. Within each replicate animals were randomly allocated to one of three groups: untreated control; IVM-CRC on Day 0; IVM-CRC on Day 84. For treatment an IVM-CRC for sheep weighing 20-45 kg was used which is designed to deliver ivermectin at a minimum dose of 20 microg/kg/day for 100 days. The lambs were infested with 50-60 P. ovis mites each on days 14 and 21. The animals were shorn on Day 126. After slaughter on Day 127 the quality of the leather produced from their skins was evaluated. The IVM-CRC treatment on Day 0 prevented the establishment of P. ovis. All untreated lambs became infested. The lambs treated with an IVM-CRC on Day 84 became mite-free from Day 112 onwards. The lambs which were treated on Day 0 had significantly (p<0.05) greater clean fleece weight (1.5 kg) and fleece yield (52.1%) than the untreated controls (0.9 kg and 34.1%, respectively) or than lambs treated on Day 84 (1.0 kg and 47.8%, respectively). Clean fleece weight and fleece yield were in the tendency (p=0.055) or significantly (p<0. 001) greater, respectively, for lambs treated on Day 84 than for the untreated controls. The chrome tanned dried crust leather of all untreated controls and six of the 16 lambs treated on Day 84 showed grain surface defects such as discolourations, indurations and coarse, pitted grain. The useful (defect-free) leather size was significantly (p<0.01) higher for the lambs treated on Day 0 (100%) than for the lambs treated on Day 84 (82.7%) and the untreated controls (7.8%). The physical testing revealed that the leather of sheep treated on Day 0 had significantly (p<0.05) higher thickness, elongation break and tear resistance than the leather of both untreated controls and sheep treated on Day 84. There were no significant differences in the physical characteristics of the leather of the untreated controls and the sheep treated on Day 84.

Animals↗

PubMed2001

Thermal and enzymatic recovering of proteins from untanned leather waste.

The laboratory trials of a process to treat untanned leather waste to isolate valuable protein products are presented. In this comparative study, both thermal and enzymatic treatments of leather waste were performed. The enzymatic method utilizes commercially available alkaline protease at moderate temperatures and for short periods of time. The concentration of the enzyme was 500 units per gram of leather waste which makes the method cost-effective. Amino acid composition in the hydrolysate obtained by the enzyme hydrolysis of untanned leather waste is determined. Chemical and physical properties of protein powder products from untanned leather waste were evaluated by spectrophotometric and chromatographic methods and by use of electron microscope. The results of microbiological assays confirm that these products agree to food safety standards. This relatively simple treatment of untanned leather waste may provide a practical and economical solution to the disposal of potentially dangerous waste.

Amino Acids↗

PubMed2002

Zero discharge tanning: a shift from chemical to biocatalytic leather processing.

Beam house processes (Beam house processes generally mean liming-reliming processes, which employ beam.) contribute more than 60% of the total pollution from leather processing. The use of lime and sodium sulfide is of environmental concern (1, 2). Recently, the authors have developed an enzyme-based dehairing assisted with a very low amount of sodium sulfide, which completely avoids the use of lime. However, the dehaired pelt requires opening up of fiber bundles for further processing, where lime is employed to achieve this through osmotic swelling. Huge amounts of lime sludge and total solids are the main drawbacks of lime. An alternative bioprocess, based on alpha-amylase for fiber opening, has been attempted after enzymatic unhairing. This totally eliminates the use of lime in leather processing. This method enables subsequent processes and operations in leather making feasible without a deliming process. A control experiment was run in parallel using conventional liming-reliming processes. It has been found that the extent of opening up of fiber bundles using alpha-amylase is comparable to that of the control. This has been substantiated through scanning electron microscopic, stratigraphic chrome distribution analysis, and softness measurements. Performance of the leathers is shown to be on a par with leathers produced by the conventional process through physical and hand evaluation. Importantly, softness of the leathers is numerically proven to be comparable with that of control. The process also demonstrates reduction in chemical oxygen demand load by 45% and total solids load by 20% compared to the conventional process. The total dry sludge from the beam house processes is brought down from 152 to 8 kg for processing 1 ton of raw hides.

Animals↗

PubMed2003

Biointervention makes leather processing greener: an integrated cleansing and tanning system.

The do-undo methods adopted in conventional leather processing generate huge amounts of pollutants. In other words, conventional methods employed in leather processing subject the skin/hide to wide variations in pH. Pretanning and tanning processes alone contribute more than 90% of the total pollution from leather processing. Included in this is a great deal of solid wastes such as lime and chrome sludge. In the approach described here, the hair and flesh removal as well as fiber opening have been achieved using biocatalysts at pH 8.0 for cow hides. This was followed by a pickle-free chrome tanning, which does not require a basification step. Hence, this tanning technique involves primarily three steps, namely, dehairing, fiber opening, and tanning. It has been found that the extent of hair removal, opening up of fiber bundles, and penetration and distribution of chromium are comparable to that produced by traditional methods. This has been substantiated through scanning electron microscopic, stratigraphic chrome distribution analysis, and softness measurements. Performance of the leathers is shown to be on par with conventionally processed leathers through physical and hand evaluation. Importantly, softness of the leathers is numerically proven to be comparable with that of control. The process also demonstrates reduction in chemical oxygen demand load by 80%, total solids load by 85%, and chromium load by 80% as compared to the conventional process, thereby leading toward zero discharge. The input-output audit shows that the biocatalytic three-step tanning process employs a very low amount of chemicals, thereby reducing the discharge by 90% as compared to the conventional multistep processing. Furthermore, it is also demonstrated that the process is technoeconomically viable.

Animals↗

PubMedDate not supplied

[Epidemiologic studies on carcinogenic risk and occupational activities in tanning, leather and shoe industries].

A review is made of the epidemiological studies of occupational cancer risks among tannery, leather and shoe industry workers. The risk of nasal cancer associated with exposure to leather dust, which had already been stressed at the beginning of the 1970's, was confirmed in recent studies. However, a decreasing trend of RR was observed among shoe industry workers. The excess of leukemia among shoe workers, which was mainly based on the description of numerous cases of acute myeloblastic leukemia, has also been confirmed by two cohort studies carried out in Italy and the U.K. In addition to the evident increase in these two diseases, there are indications of an excess of cancer of other sites among leather and shoe workers, particularly bladder cancer, both among workers assigned to leather finishing operations and in leather goods and shoe production workers. Another interesting result is the excess of lung cancer among tannery workers. This evidence is unanimous in the studies carried out in Italy but is not supported by the majority of studies performed in other countries. For this reason, we consider it extremely important to carry out a multicentric study in Italy, with particular attention to the definition of occupational exposures to carcinogens. There are also other isolated reports of excesses of other cancers in the shoe and leather industries but in our opinion they are of dubious interpretation.

Dust↗

PubMed1995

Nasal cancer in leather workers: an occupational disease.

Nasal cancer has a number of causative agents; exposures to most of the established nasal carcinogens occur in the workplace. An increased risk of nasal cancer has been ascertained in shoe-making and shoe-repairing, but the results for leather goods manufacture and leather tanning don't provide adequate evidence of carcinogenicity. Findings from two epidemiological studies carried out in Italy (a case/control study and a case/series report) add further information on this issue. The case/control study was performed in the provinces of Siena (Tuscany), Verona and Vicenza (Venetia) including 96 cases and 378 controls. A significant increased risk (Odds Ratio: 6.8; 90% C.I. = 1.9-25) of sinonasal cancer was found for the employ in the whole leather industry; Odds Ratio of 8.3 (C.I. = 1.9-36) and 5.0 (C.I. = 0.92-28) were associated with shoe-making and leather tanning. The case/series report is based on 110 patients accepted in some Italian hospitals during last three years (1990-1993): 26 cases had worked in the leather industry; adenocarcinoma is the most frequent type observed. Chromium salts and natural tannins are indicated as possible aetiological agents.

Case-Control Studies↗

PubMed2006

Use of a proteomics approach to identify favourable conditions for production of good quality lambskin leather.

It is necessary to understand the changes that occur during the initial processing of lamb skins, because these will affect the final quality of the leather. The types of collagen, their macro and micro structures, the presence of proteins other than collagens, and the quantity and the type of proteoglycans, all have a profound effect on the quality of leather. Proteins isolated from untreated or raw sheep skin and from pickled skin (skins treated with sodium sulfide and lime followed by bating with enzymes, then preserved in sodium chloride and sulfuric acid) were significantly different when analysed by use of 2D gel electrophoresis and mass spectrometry. Agarose gel electrophoresis with a very sensitive sequential staining procedure has been used to identify the glycosaminoglycans present in raw and treated skin and their impact on quality of leather. Results showed that effective removal of proteoglycans acting as inter-fibrillar adhesives of collagen fibrils seemed to improve leather quality. Removal of these molecules not only opens up the fibre structure of the skin but may also be important in wool removal. The presence of elastin, which imparts elastic properties to skin, is of significant importance to tanners. The amino acids desmosine and isodesmosine, found exclusively in elastin, were quantitatively analysed to assess the role of elastin in leather quality.

Animals↗

PubMed2002

Harmful azo colorants in leather. Determination based on their cleavage and extraction of corresponding carcinogenic aromatic amines using modern extraction techniques.

This study concerns the possibilities of using microwave-assisted extraction (MAE) or supercritical fluid extraction (SFE) for detection of harmful azo colorants in leather. After degreasing of the leather sample with SFE there follows a reductive cleavage of the azo colorants to their corresponding aromatic amines in the MAE or SFE equipment. The aromatic amines are subsequently extracted using either MAE or SFE and then finally determined by liquid chromatography with diode-array detection. The results have been compared with recoveries obtained using the German DIN method 53316. This standard method, based on conventional solvent extraction, is used in several European countries. Overall much better recoveries were obtained using MAE or SFE. With both MAE and SFE the amine recoveries of spiked leather samples were generally above 50%. The average recoveries were 62% for MAE and 60% for SFE (solvent collection) compared to 24% with the DIN method. For genuine leather samples the recoveries decreased, especially for benzidine. In this case the average values for MAE, SFE and DIN were 54, 38 and 19%, respectively. The quantification limits in leather samples using MAE or SFE were below 1 mg/kg for all amines investigated. The within-laboratory precision was generally better than 10%, varying somewhat with the analyte considered. With the proposed methodology, the amount of hazardous organic solvents used could be decreased and the sample throughput increased with at least a factor of two with less manual handling compared to the DIN method.

Amines↗

PubMed2003

Towards zero discharge of chromium-containing leather waste through improved alkali hydrolysis.

The treatment of chromium-containing leather waste (CCLW), the major solid waste generated at the post-tanning operations of leather processing, has the potential to generate value-added leather chemicals. Various alkali and enzymatic hydrolysis were compared, and calcium oxide was found to be important for effective (but still incomplete) hydrolysis. Three possible reasons are given for the incomplete hydrolysis under alkaline conditions. Data for 19 amino acids are presented for four different treatment products. On the basis of the results, a novel three-step CCLW treatment process is proposed. The gelatin extracted in the first step is chemically modified to produce leather finishing agents. The collagen hydrolysates isolated in the second step are used as proteinic retanning agents by chemical modification. The remaining chrome cake is further hydrolyzed with acids in the third step, and the obtained chromium-containing protein hydrolysates could be used for the preparation of chromium-containing retanning agents for leather industry. The proposed three-step process provides a feasible zero discharge process for the treatment of CCLW.

Animals↗

PubMed2002

Influence of dietary protein level and the amino acids methionine and lysine on leather properties of blue fox (Alopex lagopus) pelts.

The influence of dietary protein, methionine, and lysine on leather quality in blue fox pelts was studied. The pelt material originated from animals in two consecutive feeding trials (Exp. 1 and Exp. 2) with three protein levels: conventional, slightly lowered, and very low. The two lowest protein diets were fed as such or as supplemented with methionine or with lysine (lysine only in Exp. 2). The following physical leather properties were measured: breaking load (BRL), tensile strength (TEN), relative elongation at break (PEB), straining of skins at pelting, and shrinkage at dressing. A decline in the dietary protein content reduced BRL and, hence, leather firmness, and increased straining and the corresponding shrinking in Exp. 1. The supplemented methionine tended to improve leather strength and elasticity by increasing TEN and PEB in Exp. 1, whereas lysine elicited no response. Methionine supplementation at the slightly lowered protein level increased BRL in both experiments by almost 10% as compared with the respective non-supplemented diet. We conclude that with high protein quality diets, a level of 200 g/kg DM (as digestible protein) appears to be adequate for producing pelts with firm, elastic leather, provided that an adequate amount of methionine is included in the diet.

Animal Nutritional Physiological Phenomena↗

PubMed2002

Low temperature conversion of sludge and shavings from leather industry.

Abstract Brazil has one of the largest herds of cattle in the world, with more than 170 million heads. Over 400 farms have exported more than 2,875 ton (in 1997) of leather to Europe. The wet blue tanning process uses chemicals such as chromium compounds and produces liquid wastes that must be treated by physicochemical and biological systems. About 15,000 ton per month of dewatering sludge with 24% solids content is disposed of into landfills. During the process, pre-tanned skins (wet blue leather) are shaved to the desired thickness and the shavings, like sludge, are among the wastes that must have special attention. The organic content and chromium concentration are high. About 12% of the leather production from cattle hides are shavings, and its chromium concentration ranges from 3.5 to 5.5% of dry matter. The Environmentally friendly leather project, a co-operation between Brazilian and German tanneries, universities and technical schools, is looking for process optimisation, waste minimisation and adequate treatment for solid and liquid wastes from the leather industry. This work presents results of Low Temperature Conversion of chrome-containing sludge and shavings in a laboratory batch reactor, offering a solution for these hazardous wastes, recovering the energy content and transforming metals in insoluble sulphides.

Animals↗

PubMed2006

Solid waste from leather industry as adsorbent of organic dyes in aqueous-medium.

The industrial tanning of leather usually produces considerable amounts of chromium-containing solid waste and liquid effluents and raises many concerns on its environmental effect as well as on escalating landfill costs. Actually, these shortcomings are becoming increasingly a limiting factor to this industrial activity that claims for alternative methods of residue disposals. In this work, it is proposed a novel alternative destination of the solid waste, based on the removal of organic contaminants from the out coming aqueous-residue. The adsorption isotherm pattern for the wet blue leather from the Aurea tanning industry in Erechim-RS (Brazil) showed that these materials present high activity on adsorbing the reactive red textile dye as well as other compounds. The adsorbent materials were characterized by IR spectroscopy and SEM and tested for the dye adsorption (reactive textile and methylene blue dyes). The concentrations of dyes were measured by UV-vis spectrophotometry and the chromium extraction from leather waste was realized by basic hydrolysis and determined by atomic absorption. As a low cost abundant adsorbent material with high adsorption ability on removing dye methylene blue (80mgg(-1)) and textile dye reactive red (163mgg(-1)), the leather waste is revealed to be a interesting alternative relatively to more costly adsorbent materials.

Adsorption↗

PubMed1995

Acute pulmonary toxicity linked to use of a leather protector.

Leather protectors are used extensively for waterproofing leather garments. Inhalation exposure to this type of product is usually considered a benign incident. We report two cases of acute pulmonary toxicity associated with the use of a new leather protector recently introduced to the Canadian market. Emergency physicians must be aware of the potential acute toxicity of new leather protectors.

Adolescent↗

PubMed2002

Quantitative aspects of contact allergy to chromium and exposure to chrome-tanned leather.

The potential of trivalent and hexavalent chromium to induce and elicit allergic contact dermatitis and the degree of chromium exposure from leather products are reviewed. Chromium dermatitis is often due to exposure in the occupational environment, with cement being one of the most common chromium sources. However, consumer products such as chromium(III)-tanned leather products are also an important source of chromium exposure. Apart from Cr(III), which is used for tanning, leather often also contains trace amounts of Cr(VI), which is formed by oxidation of Cr(III) during the tanning process. In a recent study of the Cr(VI) content of leather products bought on the Danish market, 35% of such articles had a Cr(VI) content above the detection limit of 3 p.p.m., ranging from 3.6 p.p.m. to 14.7 p.p.m. Leachable Cr(III) was detected at levels of 430-980 p.p.m. An examination of available dose-response studies showed that exposure to occluded patch test concentrations of 7-45 p.p.m. Cr(VI) elicits a reaction in 10% of the chromium-sensitive patients. When reviewing repeated open exposure studies, it is seen that either exposure to 5 p.p.m. Cr(VI) in the presence of 1% sodium lauryl sulfate (SLS) or exposure to 10 p.p.m. Cr(VI) alone both elicit eczema in chromium-sensitive patients. The eliciting capacity of Cr(III) has not been systematically investigated but, compared to Cr(VI), much higher concentrations are needed to elicit eczema.

Allergens↗

PubMed2003

The effects of treating bovine hide with steam at subatmospheric pressure on bacterial numbers and leather quality.

AIMS: To examine the effect of subatmospheric steam treatment on total viable counts (TVCs) on bovine hide and on the quality of derived leather. METHODS AND RESULTS: Pieces of bovine hide were heated to 75 degrees C (+/-2 degrees C) (n = 3) or 80 degrees C (+/-2 degrees C) (n = 3) for periods of 1, 10 or 20 s by the application of steam at subatmospheric pressure in a laboratory scale apparatus. Treated hide pieces and untreated controls were tanned and the quality of leather was assessed. Treatment at 80 degrees C (T80) reduced the TVC on hide pieces by 2.95 (1 s), 3.33 (10 s) and 3.99 (20 s) log10 CFU cm-2 (P > 0.05). Treatment at 75 degrees C (T75) reduced the TVC on hide pieces by 1.87 (1 s), 2.51 (10 s) and 2.56 (20 s) log10 CFU cm-2 (P > 0.05). The grain on all treated hides was damaged resulting in sueding on derived leather. Sueding was observed on 100% of surfaces from T80-treated samples and on 18 (1 s) to 84% (20 s) of the surfaces of T75 samples. CONCLUSIONS: The magnitude of TVC reductions achieved using T75 and T80 could limit the impact and scale of contamination transfer to the carcass during dehiding. However, because of the sueding observed on derived leather, it is unlikely that either T75 or T80 would be a commercially valid operation during routine slaughter operations. SIGNIFICANCE AND IMPACT OF THE STUDY: Hide decontamination would provide an important critical control point for beef processing, however there are currently no commercially available treatments.

Abattoirs↗

PubMed2001

Allergic contact dermatitis from a pyridine derivative in polyvinyl chloride leather.

Antimicrobial coating of household products has gained wide acceptance in Japan in the past several years. Pyridine derivatives, used as antifungal or antibacterial agents in many common products, are known to cause contact dermatitis. We present a case of severe contact dermatitis caused by a pyridine derivative used as an antifungal agent in the polyvinyl chloride (PVC) leather of a chair. An open patch test was performed with each ingredient of the PVC leather. Other products were previously eliminated from consideration based on a series of negative patch tests. The PVC leather obtained from the patient's chair gave a ++ reaction with evident blistering, according to the International Contact Dermatitis Research Group standard. Fifteen ingredients of the PVC leather were open patch tested; a positive reaction was found with 2,3,5,6-tetrachloro-4 (methylsulphonyl) pyridine (1% in petrolatum). Clinicians should be aware that antifungal or antibacterial agents may be increasingly incorporated into common household products and should be suspected in cases of contact dermatitis.

Adult↗

PubMed2004

Increase in exhaled nitric oxide in shoe and leather workers at the end of the work-shift.

BACKGROUND: Measurement of nitric oxide (NO) in exhaled air is a non-invasive procedure for assessing airway or pulmonary inflammation, and for evaluating environmental irritant effects of air pollution. The objective of this study was to evaluate exhaled NO levels in synthetic leather workers exposed to organic solvents toluene, xylene and methylethyl ketone. METHODS: Seventeen shoe and leather workers and 10 controls from administrative personnel of the factory were studied. The levels of exhaled NO at baseline and at the end of the work shift were measured using a standardized chemiluminescence technique. Environmental assay of the three solvents was also assessed during the working day. RESULTS: Environmental solvent concentrations were high but within permissible exposure levels. Exhaled NO concentrations increased by 40% in the leather workers at the end of the working day from a mean +/- SD of 9.1 +/- 1.3 p.p.b. to 12.8 +/- 1.7 p.p.b. (P < 0.02), as compared to the controls. CONCLUSION: Exhaled NO is increased in shoe and leather workers exposed to solvents at the end of work shift, while it does not change in unexposed subjects of the same factory. Exhaled NO may be a sensitive tool to monitor sub-clinical effects of occupational pro-inflammatory substances.

Adult↗