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PubMed1988

Coating of proteins to polystyrene ELISA plates in the presence of detergents.

The influence of several detergents on protein coating of polystyrene plates has been investigated. At concentrations equal to or higher than their respective critical micelle concentration (CMC) all detergents prevent attachment of proteins to polystyrene. However, coating of proteins on polystyrene plates can be achieved in the presence of detergents at concentrations 10-100 times lower than their CMC values. There is a strong correlation between the CMC and the detergent concentration inhibiting protein binding to polystyrene by 50%. The rank correlation coefficient for the binding of thyroid plasma membrane antigens was 0.97 (P less than 0.01). The influence of a detergent on the efficiency of protein coating of plastic surfaces also depends to some extent on protein-detergent interactions. Attachment of small hydrophilic proteins such as human IgG is more strongly inhibited by detergents than is the coating of hydrophobic thyroid plasma membrane antigens or thyroglobulin. Some detergents do not interfere with protein attachment to plastics and permit subsequent ELISA assays for hydrophobic, detergent solubilized plasma membrane proteins.

Cell Membrane↗
PubMed1993

Protein partitioning in detergent-based aqueous two-phase systems.

Aqueous solutions of nonionic polyoxyethylene detergents form two liquid phases upon temperature increase above the cloud point. One of these phases is detergent-enriched and called the coacervate phase, whereas the other is detergent-depleted. Protein partitioning in such detergent-based aqueous two-phase systems was studied systematically and quantitatively, employing a series of similar polyoxyethylene detergents and proteins of varying hydrophobicity. Increasing the detergent alkyl chain length, temperature or salt concentration leads to an increase of detergent separating into the coacervate phase and a concomitant increase of protein. The positive correlation between protein hydrophobicity and partitioning into the coacervate phase confirms that protein-detergent interactions in such systems are primarily hydrophobic. These detergent-based systems can be applied to membrane proteins as well as water-soluble proteins which possess hydrophobic domains.

Animals↗
PubMed2005

A colorimetric determination for glycosidic and bile salt-based detergents: applications in membrane protein research.

Detergents are crucial to the isolation of integral membrane proteins. During membrane protein purification, it is useful to accurately quantify detergent, especially if concentration steps have been used. Previously, this has been difficult and time-consuming. We present a simple, rapid, and sensitive procedure for the quantification of glycosidic and bile salt-based detergents such as dodecylmaltoside, octylglucoside, and CHAPS. The method directly quantifies sugar or cholate moieties via colorimetric reactions with phenol and sulfuric acid. A number of detergents have been screened, and the assay has been validated in the presence of commonly used reagents. In addition to determining the overall detergent concentration in solution, the procedure allows accurate quantification of specific binding of glycosidic or bile salt-based detergents to purified membrane proteins. Both the colorimetric method and the radiometric 14C method were used to determine detergent binding to two integral membrane proteins: the cytochrome cbb3 oxidase from Pseudomonas stutzeri and the turkey beta-adrenergic receptor. Both methods gave similar results. After separating monomeric glycosidic detergent from micellar solutions by ultrafiltration, we used the colorimetric method to determine the concentration of monomeric detergent present. We observed that values obtained are in close agreement with previously determined critical micelle concentrations.

Bile Acids and Salts↗
PubMed2005

Detergents induce raft-like domains budding and fission from giant unilamellar heterogeneous vesicles: a direct microscopy observation.

The effect of detergents on giant unilamellar vesicles (GUVs) composed of phosphatidylcholine, sphingomyelin and cholesterol and containing liquid-ordered phase (l(o)) domains was investigated. Such domains have been used as models for the lipid rafts present in biological membranes. The studied detergents included lyso-phosphatidylcholine, the product of phospholipase A2 activity, as well as Triton X-100 and Brij 98, i.e. detergents used to isolate lipid rafts as DRMs. Local external injection of each of the three detergents at subsolubilizing amounts promoted exclusion of l(o) domains from the GUV as small vesicles. The budding and fission processes associated with this vesiculation were interpreted as due to two distinct effects of the detergent. In this framework, the budding is caused by the initial incorporation of the detergent in the outer membrane leaflet which increases the spontaneous curvature of the bilayer. The fission is related to the inverted-cone molecular shape of the detergent which stabilizes positively curved structures, e.g. pores involved in vesicle separation. On the other hand, we observed in GUVs neither domain formation nor domain coalescence to be induced by the addition of detergents. This supports the idea that isolation of DRM from biological membranes by detergent-induced extraction is not an artifact. It is also suggested that the physico-chemical mechanisms involved in l(o) domain budding and fission might play a role in rafts-dependant endocytosis in cells.

Cholesterol↗
PubMed2003

Control of occupational asthma and allergy in the detergent industry.

OBJECTIVE: To provide an overview of how a comprehensive preclinical, clinical, and industrial hygiene program has been successfully used to control allergy and asthma to enzymes used in the detergent industry. DATA SOURCES: The author performed a PubMed and ToxLine search of English-language articles with the keywords enzymes, occupational allergy, occupational asthma, detergent, and detergent industry from January 1, 1995, to January 1, 2002. Scientific meeting abstracts, books, and industry association papers on allergy and asthma in the detergent industry were also reviewed. In addition, the practical experience of one major detergent company was included in the review. STUDY SELECTION: All published work on this topic was reviewed, and the work that discussed the key highlights of control of occupational allergy and asthma to enzymes used in the detergent industry was selected for this review. RESULTS: The detergent industry has developed guidelines for the safety assessment of enzymes, control of exposure to enzymes, and medical surveillance of enzyme-exposed workers. Because of these guidelines, occupational allergy and asthma to enzymes used in the detergent industry have become uncommon events. Cases of disease have been documented in some manufacturing sites that have had poor adherence to the guidelines. Those manufacturing sites that have adhered to the guidelines have had few cases of allergy and asthma to enzymes among exposed workers. A review of medical data from these sites has shown that workers who have developed IgE antibody to enzymes can continue to work with enzymes and remain symptom free. CONCLUSIONS: Occupational allergy and asthma to enzymes used in the detergent industry have been successfully controlled via the use of preclinical, clinical, and industrial hygiene safety programs designed to minimize sensitization to enzymes and development of disease. The basic principles of these programs can be applied to other industries where occupational allergy and asthma to proteins are common.

Asthma↗
PubMed1984

Solubilization and immunoprecipitation of 125I-labelled antigens from Plasmodium knowlesi schizont-infected erythrocytes using non-ionic, anionic and zwitterionic detergents.

Plasmodium knowlesi malaria-infected erythrocytes were radio-iodinated and several non-ionic, anionic and zwitterionic detergents were compared in their capacity to extract the labelled membrane proteins. The use of these detergents for antigen identification was tested by immunoprecipitation, after addition of Triton X-100 to some detergent extracts, using hyperimmune monkey antiserum and protein A-Sepharose. 125I-labelled antigens were specifically immunoprecipitated with all detergents tested, including the anionic detergents sodium dodecyl sulphate (SDS), deoxycholate and cholate; the zwitterions Zwittergent-312 and -314, CHAPS and Empigen BB, as well as several non-ionic detergents. The SDS-polyacrylamide gel electrophoresis patterns of 125I-labelled antigens varied after extraction with different detergents, there being no consistent pattern for detergents of a particular class. A total of 14 125I-labelled antigens were identified, 11 of them using Triton X-100. Some minor 125I-labelled antigens identified with Triton X-100 were immunoprecipitated in greater amount after extraction in other detergents. Most importantly, two antigens Mr 200 000 and 180 000 were detected only after extraction with deoxycholate or SDS.

Animals↗
PubMed1984

Phospholipid vesicle formation using nonionic detergents with low monomer solubility. Kinetic factors determine vesicle size and permeability.

The method developed previously for formation of unilamellar vesicles from mixed micelles of egg lecithin and octyl glucoside [Mimms, L. T., Zampighi, G., Nozaki, Y., Tanford, C., & Reynolds, J. A. (1981) Biochemistry 20, 833-840] has been extended to allow for (1) use of nonionic detergents with much lower critical micelle concentrations and (2) variation in the time course of detergent removal. The results demonstrate the importance of kinetic factors, especially in the determination of vesicle size: initially formed vesicles are small, but the size increases slowly thereafter if detergent is not removed too quickly. Vesicle size remains fixed when the molar detergent/lipid ratio falls below about 1/1, and detergent removal becomes increasingly difficult thereafter, presumably because flip-flop of detergent from the inner to the outer leaflet of the bilayer membrane is very slow. Residual detergent (to about 25 mol %) has surprisingly little effect on anion permeability but increases cation permeability to the point where the normal discrimination between anions and cations (in pure lipid vesicles) is lost. Detergent added to initially detergent-free vesicles readily partitions into vesicular membranes (presumably only into the outer leaflet) and has a qualitatively similar effect on permeability. Vesicles produced by this method, regardless of residual detergent level, were found to be predominantly unilamellar: no multilamellar liposomes or other lipid aggregates could be detected within the accuracy of the methods employed.

Detergents↗
PubMed1985

Effects of detergent on substrate binding and spin state of purified liver microsomal cytochrome P-450LM2 from phenobarbital-treated rabbits.

Spectral changes accompanying the binding of the nonionic detergent n-octyl beta-D-glucopyranoside (n-octyl glucoside) to cytochrome P-450LM2 purified from liver microsomes of phenobarbital-treated rabbits have been compared to changes in catalytic activity obtained in a reconstituted system consisting of various levels of detergent, P-450LM2, and NADPH-cytochrome P-450 reductase. In the absence of substrate and reductase, addition of n-octyl glucoside to 2-3 mM resulted in a difference spectrum (detergent-bound minus detergent-free cytochrome) characterized by a small maximum at 390 nm and a minimum at 410 nm, suggestive of a slight stabilization of the high-spin (S = 5/2) state of the cytochrome. As the detergent concentration was increased to 4-8 mM (corresponding to maximal activity and pentameric or hexameric P-450), a new peak appeared at 427 nm while the minimum remained at 410 nm. Between 10 and 30 mM n-octyl glucoside (conditions which produced catalytically inactive and monomeric P-450) the minimum in the difference spectrum shifted to 390 nm and the maximum to 425 nm, characteristic of a shift in spin equilibrium toward low-spin (S = 1/2) cytochrome. At low and high detergent concentrations, substrate [d-benzphetamine with n-octyl glucoside or cyclohexane with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS)] was bound to P-450LM2 with formation of high-spin P-450, although the increase in high-spin cytochrome was less at high detergent levels than at low. The affinity of P-450 for substrate decreased by 2-3-fold at high detergent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Deoxylysolecithin and a new biphenyl detergent as solubilizing agents for bovine rhodopsin. Functional test by formation of metarhodopsin II and binding of G-protein.

The protein-detergent interaction in rhodopsin-detergent micelles has been investigated by using formation of metarhodopsin II (MII) as a monitor. Two detergents of different structural rigidity have been applied. One of them is [3-(lauroyloxy)propyl]phosphorylcholine, which has a high conformational flexibility in its hydrophobic moiety like most of the known detergents for rhodopsin. This deoxylysolecithin was originally designed as a detergent for membrane proteins by Weltzien [Weltzien, H. U. (1979) Biochim. Biophys. Acta 559, 259-287]. The other detergent, which is highly rigid in its hydrophobic part, has been developed for this study. It consists of a biphenyl derivative and a hydrophilic octaethylene oxide group. Both the formation kinetics of MII and the position of its equilibrium with its tautomeric form, metarhodopsin I (MI), strongly differed in the deoxylysolecithin and biphenyl detergent. Deoxylysolecithin caused very fast MII formation and shifted the equilibrium strongly to MII, like other detergents with alkyl chains as the hydrophobic part. In the biphenyl detergent, however, formation of MII was slow and the MI/MII equilibrium similar to that in the native system. For rhodopsin reconstituted in lipid bilayers, normal MII formation requires a well-adjusted fluidity of the hydrocarbon environment of the protein [Baldwin, P. A., & Hubbell, W. L. (1984) Biochemistry 24, 2633-2639], which was explained by an appropriate interfacial pressure at the protein-lipid interface. Extension of this concept would indicate that in the micellar core a degree of fluidity comparable to that of the disk membrane is just achieved with the highly rigid biphenyl structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Mechanisms of membrane protein insertion into liposomes during reconstitution procedures involving the use of detergents. 1. Solubilization of large unilamellar liposomes (prepared by reverse-phase evaporation) by triton X-100, octyl glucoside, and sodium cholate.

The mechanisms governing the solubilization by Triton X-100, octyl glucoside, and sodium cholate of large unilamellar liposomes prepared by reverse-phase evaporation were investigated. The solubilization process is described by the three-stage model previously proposed for these detergents [Lichtenberg, D., Robson, R.J., & Dennis, E.A.(1983) Biochim. Biophys. Acta 737, 285-304]. In stage I, detergent monomers are incorporated into the phospholipid bilayers until they saturate the liposomes. At that point, i.e., stage II, mixed phospholipid-detergent micelles begin to form. By stage III, the lamellar to micellar transition is complete and all the phospholipids are present as mixed micelles. The turbidity of liposome preparations was systematically measured as a function of the amount of detergent added for a wide range of phospholipid concentrations (from 0.25 to 20 mM phospholipid). The results allowed a quantitative determination of RSat, the effective detergent to lipid molar ratios in the saturated liposomes, which were 0.64, 1.3, and 0.30 for Triton X-100, octyl glucoside, and sodium cholate, respectively. The corresponding ratios in the mixed micelles, RSol, were 2.5, 3.8, and 0.9 mol of detergent/mol of phospholipid. The monomer concentrations of the three detergents in the aqueous phase were also determined at the lamellar to micellar transitions (0.18, 17, and 2.8 mM, respectively). These transitions were also investigated by 31P NMR spectroscopy, and complete agreement was found with turbidity measurements. Freeze-fracture electron microscopy and permeability studies in the sublytic range of detergent concentrations indicated that during stage I of solubilization detergent partitioning between the aqueous phase and the lipid bilayer greatly affects the basic permeability of the liposomes without significantly changing the morphology of the preparations. A rough approximation of the partition coefficients was derived from the turbidity and permeability data (K = 3.5, 0.09, and 0.11 mM-1 for Triton X-100, octyl glucoside, and sodium cholate, respectively). It is concluded that when performed systematically, turbidity measurements constitute a very convenient and powerful technique for the quantitative study of the liposome solubilization process by detergents.

Bacteriorhodopsins↗
PubMed1981

Kinetics and protein subunit interactions of Escherichia coli phosphatidylserine decarboxylase in detergent solution.

Phosphatidylserine decarboxylase from Escherichia coli, an intrinsic membrane protein, catalyzes the conversion of phosphatidylserine to phosphatidylethanolamine. The physical and kinetic properties of the purified enzyme were studied in several detergents under assay conditions. The active form of the enzyme is an oligomer, probably a trimer, and the enzyme activity was unaffected by the concentration of the nonionic poly(oxyethylene) ether detergent present in the assay medium, so long as the detergent micelle/substrate mole ratio was less than one. When this ratio was greater than one, the detergent acted as an inhibitor by competing with enzyme-containing micelles for substrate. The zwitterionic and bile salt detergents that were tested inactivated the enzyme by dissociating the oligomer. The native, Triton X-100 solubilized, enzyme was modified with a cross-linking reagent. Activity of the cross-linked enzyme was retained after the Triton X-100 was replaced by a zwitterionic sulfobetaine detergent and conformed to the same kinetic model as with the poly(oxyethylene) ether detergents. The cross-linked enzyme was also active when solubilized by the bile salt detergents although the activity did not conform to any simple kinetic model. These data indicate that the oligomer is the active form of the enzyme under assay conditions and that certain nondenaturing detergents can inactivate this enzyme by dissociating the enzyme complex.

Animals↗
PubMed1979

Detergent inactivation of sodium- and potassium-activated adenosinetriphosphatase of the electric eel.

The stability of the sodium- and potassium-activated adenosinetriphosphatase (Na,K-ATPase) of the electric eel, Electrophorus electricus, was studied in five detergents in an effort to establish conditions for reconstitution of this membrane protein into defined phospholipids. The Na,K-ATPase activity of purified electric organ membranes as well as the ATPase is stable for at least 1 month of storage at 0 degrees C in the absence of detergents. At low concentrations of detergents, the enzyme is also stable for several days, but irreversible inactivation occurs rapidly as the detergent concentration is further increased. This inactivation begins at well-defined threshold concentrations for each detergent, and these concentrations generally occur in the order of the detergent critical micelle concentrations. Increasing the concentration of the electric organ membranes causes a linear increase in the inactivation threshold concentrations of Lubrol WX, deoxycholate, and cholate. The onset of inactivation evidently occurs when the mole fraction of detergent associated with the membrane lipids reaches a critical value in the narrow range of 0.2-0.4, in contrast to the large differences in the bulk concentrations of these detergents. The eel Na,K-ATPase is more sensitive to detergents than the sheep kidney enzyme.

Animals↗
PubMed1977

Activities of lectins and their immobilized derivatives in detergent solutions. Implications on the use of lectin affinity chromatography for the purification of membrane glycoproteins.

The effects of several commonly used detergents on the saccharide-binding activities of lectins were investigated using lectin-mediated agglutination of formalin-fixed erythrocytes and affinity chromatography of glycoproteins on columns of lectins immobilized on polyacrylic hydrazide-Sepharose. In the hemagglutination assays, Ricinus communis I (RCA1) and II (RCAII), concanavalin A (Con A), and the agglutinins from peanut (PNA), soybean (SBA), wheat germ (WGA), and Limulus polyphemus (LPA) were tested with several concentrations of switterionic, cationic, anionic, and nonionic detergents. It was found that increasing detergent concentrations eventually affected hemagglutination titers in both test and control samples, and the highest detergent concentrations not affecting lectin hemagglutinating activities were determined. The effects of detergents on specific binding of [3H]fetuin and asialo[3H]fetuin to and elution from columns of immobilized lectins were less severe when compared with lectins in solution, suggesting that the lectins are stabilized by covalent attachment to agarose beads. Nonionic detergents did not affect the binding efficiency of the immobilized lectins tested at concentrations used for membrane solubilization while cationic and zwitterionic detergents caused significant inhibition of Con A- and SBA-Sepharose activities. In sodium deoxycholate (greater than 1%) only RCAI-Sepharose retained its activity, whereas the activities of the other lectins were reduced dramatically. Low concentrations of sodium dodecyl sulfate (0.05%) inhibited only the activity of immobilized SBA, but at higher concentration (0.1%) and prolonged periods of incubation (16 h, 23 degrees C) most of the lectins were inactivated. These data are compared with previous reports on the use of detergents in lectin affinity chromatography, and the conditions for the optimal use of detergents are detailed.

Chromatography, Affinity↗
PubMed2006

Glutaraldehyde cross-linking of lipases adsorbed on aminated supports in the presence of detergents leads to improved performance.

Lipases from Candida rugosa (CRL) and lipase isoforms A and B from Candida antarctica (CAL-A and CAL-B) were adsorbed on aminated supports in the presence of detergents to have individual lipase molecules. Then, one fraction was washed to eliminate the detergent, and both preparations were treated with glutaraldehyde. The presence of detergent during the cross-linking of the lipases to the support permitted an increase in the recovered activity (in some instances, even by a 10-fold factor). This activity was higher even than that exhibited by the just adsorbed lipases, suggesting that it was not a result of some protective effect of the detergent in the enzyme activity during glutaraldehyde chemical modification. Moreover, the enantioselectivity of the different enzyme preparations was very different if the glutaraldehyde was offered in the presence or in the absence of detergent, in some cases increasing the E value (even by a 7-fold factor in the case of CAL-A in the hydrolysis of (+/-)-2-hydroxy-4-phenylbutyric acid ethyl ester), in other cases even inverting the enantio preference (e.g., in the case of CRL). The irreversible chemical inhibition of the enzyme that was immobilized and cross-linked with glutaraldehyde in the presence of detergents was more rapid than that in the other preparations (by more than a 10-fold factor). This experiment reveals an exposition degree of the active serine in the preparation cross-linked with the support in the presence of detergent that is higher than that in the other preparations. The results suggested that different enzyme structures were "stabilized" by the glutaraldehyde treatment if performed in the presence or in the absence of detergent, and that, in the presence of detergent, a form of the lipase with the serine residue more exposed to the medium and much more active could be obtained. This strategy seems to be of general use to improve the lipase activity to be used in macroaqueous media.

Adsorption↗
PubMed2002

A skin sensitization safety assessment of a new bleach activator technology in detergent applications.

A new chemical called nonanoyl amido caproylacid oxybenzenesulphonate (NACAOBS) is being developed for use as a bleach activator in laundry detergents. Bleach activators, like NACAOBS, are typically used at levels between 2% and 6% in laundry detergents. NACAOBS is stable in aqueous solutions, but undergoes rapid perhydrolysis when combined with water and peroxygen bleach in laundry detergents. Animal testing demonstrated that NACAOBS, as a raw material, is a weak skin sensitizer. Clinical testing, including extended simulated laundry pretreatment, human repeat insult patch testing and home use testing was then undertaken, following sufficient reassurance of 1) the weak sensitization potential of the substance, 2) its rapid degradation in laundry wash solutions and, consequently, 3) low-to-negligible consumer dermal exposures to the native substance. Results confirmed the skin sensitization safety profile of laundry detergents containing NACAOBS, namely the absence of any reaction suggestive of contact sensitization (even under exaggerated dermal exposure conditions in a detergent matrix), and a skin compatibility profile comparable to that of current detergents. Further confirmation of the skin safety profile was obtained from a successful 12-month market test of a granular detergent containing 3.6% of the new substance, during which not a single adverse skin reaction was reported. In addition, NOBS (an oxybenzenesulphonate structural analogue to NACAOBS) has similar toxicological properties and has been safely marketed in detergents at similar levels for many years. It can be concluded that the likelihood of NACAOBS to induce skin sensitization or even elicit allergic reactions in consumer detergent use scenarios is negligible.

Animals↗
PubMed2005

Refractive index-based determination of detergent concentration and its application to the study of membrane proteins.

The concentration of detergent in membrane protein preparations can have a critical role on protein stability, function, and the potential for crystallization. Unfortunately, dialysis or protein concentration can lead to an unknown amount of detergent in the final membrane protein preparations. Here we present a method for the determination of detergent concentration based on refractive index of the detergent solution. This method was applied to quantitate the amount of detergent remaining in solution after concentration in various concentrators. We found that the ability of the tested detergents to pass through the molecular weight cutoff membrane correlates well with detergent micelle size. Therefore, the micelle size can be used as a rough guide to estimate the retention of a given detergent in various molecular weight cutoff concentrators. The refractive index method is exceptionally informative when coupled with size exclusion chromatography and light scattering, and can be used to determine the oligomeric state of the membrane protein, the size of a protein-associated micelle, as well as the amount and size of the unbound detergent micelle.

Chromatography, Gel↗
PubMed1985

Destabilization of collagen structure by amides and detergents in solution.

The effects of amides and detergents on collagen to gelatin transition have been studied at neutral pH. Simple amides denature the protein. The substitution of H-atoms by the alkyl groups at the nonpolar end of amide increases the effectiveness of the compounds in destabilizing the collagen structure whereas substitution of the H-atom at the polar amide end shows marginal effects on the collagen transition. The capabilities of these reagents to denature collagen are much less pronounced than their effects on denaturing globular proteins. Anionic detergents are found to destabilize collagen at very low concentrations (below their cmc values). In this respect, the effects of the detergents on collagen are comparable to the denaturing effects of the detergents on globular proteins. The effect of detergents increases with the increase in the length of the alkyl chain. The structure of the anion in the detergent is also important as seen from the lower potency of the sulfonate containing detergent compared to the sulfate containing detergent in denaturing collagen. Cationic and nonionic detergents do not denature collagen.

Amides↗
PubMed1996

Automatic dishwasher detergent poisoning: opportunities for prevention.

We investigated the antecedents of ingestion of dishwashing machine detergent to enable the development of effective countermeasures. Parents who had sought advice from the Victorian Poisons Information Centre about dishwasher detergent poisoning exposures of their children were interviewed by telephone. Almost all the children (94 per cent) were aged between 6 and 29 months. Of the 61 children included in the survey, 53 (87 per cent) gained access to the detergent from the dishwasher. Of these, 50 (94 per cent) took the detergent from the dispenser on the internal surface of the door of the machine, and 38 (76 per cent) of these ingested detergent remaining in the dispenser after operation of the machine. Parents were present in the room on 78 per cent of occasions at the time of ingestion. Most parents (72 per cent) were aware of the toxicity of the detergents. Relocation of the dispenser or redesigning it to prevent access both before and after operation would have prevented most of the exposures to detergent. Altering the detergent to prevent caking or sludging might prevent many of the exposures to detergent remaining in the dispenser after operation of the machine. The level of prior knowledge about toxicity suggests that education or additional warnings are unlikely to contribute substantially to prevention of poisoning. Telephone call-back to identified cases is a useful method of investigating complex poisoning problems and developing effective countermeasures.

Child, Preschool↗