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Proximal chondroepiphyseal injuries of the humerus constitute a very low percentage of traumatic growth pathologies, at around 5% of all fractures during childhood. The treatment most commonly used is conservative, with simple immobilization; nonetheless, in rare cases where surgery is planned, numerous methods of reduction and internal fixation have been proposed. The authors propose their experience in the treatment of a small (3 cases) homogeneous group (Salter-Harris type II) of proximal chondroepiphyseal injuries of the humerus by closed reduction in 2 cases, open reduction in 1, and percutaneous fixation with simple Kirschner wires. The results obtained are excellent, without any complications or sequelae, and with complete recovery of joint range of movement. The authors emphasize the use of this method capable of allowing for early mobilization, thus allowing for the child's rapid and non-traumatic return to a social life.

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Seven carbon black pastes used as commercial leather dyes were tested for their mutagenicity in the Salmonella/microsome test (TA98 and TA100 strains). All the samples assayed either directly or after extraction with a 30-min sonication in benzene were devoid of mutagenicity both in the presence and absence of a metabolic activation preparation. After a 48-h extraction with boiling toluene in a Soxhlet apparatus, four samples were mutagenic in TA98 strain in the presence of S9 mix. The activity ranged from 1.3 to 9.6 induced revertants/mg equivalent of extract. A weak direct mutagenic activity in strain TA98 was shown by one extract. Polycyclic aromatic hydrocarbons (PAH) were determined in the toluene extracts by high resolution gas chromatography/mass spectrometry. The presence of PAH could explain the mutagenicity of only one sample (8.79 micrograms of total PAH/100 mg equivalents of extract), while low or undetectable levels of PAH were found in the other mutagenic extracts. The mutagenic activity was evident only after a vigorous extraction process, thus a low bioavailability of the mutagens present in these compounds is suggested.

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Seventeen tannins used in the hide and leather industry, most of which contain mainly Cr(III) sulphates, were tested for the ability to directly induce gene mutations in Salmonella typhimurium (TA 100 strain) and chromosomal effects (sister chromatid exchanges, SCE) in cultured hamster cells (CHO line). Total chromium [Cr(III) + Cr(VI)] content and contaminating Cr(VI) were determined spectrophotometrically by reaction with diphenylcarbazide. None of the tested compounds induced gene mutations, whereas eight tannins were able to increase significantly the frequency of SCE. A contamination with Cr(VI) was detected in four compounds (from 30 up to 100 parts of Cr(VI) per 10(6) parts of compound), insufficient to be revealed by the Salmonella assay but sufficient to account for the observed SCE increase. On the other hand, the increase of SCE induced by the other four tannins could not be explained by the level of Cr(VI) contamination, and can be ascribed to other impurities present in those industrial compounds. These four tannins did not induce gene mutations in the S. typhimurium assay even when strain TA 98 was used in addition to TA 100, independently of microsomal activation. By prolonging the time of the SCE assay from 30 to 48 h in order to facilitate Cr(III) endocytosis, a significant increase of the SCE frequency was induced by an analytical-grade Cr(III) reagent (chromium chloride), absolutely uncontaminated by Cr(VI), as well as by three Cr(III) tannins, otherwise inactive in the SCE assay.

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The influence of nitrilotriacetic acid trisodium salt (NTA) on the mutagenic and clastogenic activity of several water-insoluble or poorly soluble chromium compounds was determined by means of the Salmonella/microsome assay (plate test on TA100 strain) and the sister-chromatid exchange (SCE) test in mammalian cell cultures (CHO line). NTA in itself did not induce gene mutations nor did it increase the frequency of SCE. Cr(VI) compounds (Pb, Ba, Zn, Sr and Ca chromates) and an industrial Cr(VI) pigment, chromium orange (containing PbCrO4 PbO), were inactive or scarcely active mutagens in the Salmonella/microsome test when dissolved in water, but they were increasingly mutagenic when solubilized by 0.5 N NaOH or NTA (10 or 100 mg/ml). Also, the mutagenic activity of Cr(VI), contaminating an industrial Cr(III) pigment (chromite), was slightly enhanced by NTA. Mutagenicity of chromates was correlated with the amounts of Cr(VI) solubilized by NTA or alkali, as determined by the colorimetric reaction with diphenylcarbazide and atomic absorption spectrophotometry, and was decreased by incubation with microsomes, due to reduction of Cr(VI) to the genetically inactive Cr(III) form. In the SCE assay, the insoluble or poorly soluble Ba, Zn, Sr and Ca chromates and the insoluble Cr(VI) pigments zinc yellow (containing ZnCrO4 Zn(OH2], chromium yellow and molybdenum orange (both containing PbCrO4) were directly clastogenic due to cellular endocytosis taking place in prolonged treatments, and NTA significantly increased their chromosome-damaging activity.

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