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Cadmium (Cd) as nephrotoxicant metal exerts its potent effect mainly on renal tubules disturbing its functions. A cross-sectional study was conducted on 55 sewage workers occupationally exposed to Cd and 50 control subjects. The study aimed to assess the effect of low-level Cd exposure on blood pressure and renal function in terms of serum cystatin-C levels. The associations between genetic polymorphisms of ACEI/D and ACE G2350A and hypertension and tubular injury among workers were studied. We analyzed blood and urine Cd concentration (U-Cd), serum cystatin-C, ACE I/D polymorphisms, and ACE G2350A, and blood pressure was measured. Results recorded a significant rise in serum and U-Cd and cystatin-C levels in sewage workers compared with controls. Significant distribution in genotype frequency of ACE I/D and ACE G2350A gene was detected. An association in DD genotype of ACE I/D with a rise in serum and U-Cd was observed in workers. In wild type genotype GG of ACE G2350A gene, a significant rise in serum cystatin-C levels and diastolic pressure was found while in heterozygote genotype GA significant rise in U-Cd levels was detected. Also, the association of AA genotype of ACE G2350A gene with a significant rise in serum and U-Cd and cystatin-C levels was shown among workers compared with control groups. Our findings indicated an association of ACE DD polymorphism in conjugation with GG genotype of ACE2 with hypertension and tubular injury in sewage workers.

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OBJECTIVES: Noise-induced hearing loss (NIHL) is a frequent and irreversible industrial-health problem, the early diagnosis of which can prevent hearing deterioration, especially of speech frequencies. This study aimed to assess hearing impairment in workers occupationally exposed to noise. Audiometric notches and IL-1ß gene polymorphisms were evaluated. METHODS: The study included 98 workers employed in a textile factory. Pure-tone audiometric testing was conducted for all workers, using a manual pure-tone diagnostic audiometer, and the noise level was measured at four different work sites in a spinning section. IL-1ß gene polymorphism was determined using PCR-RFLP methods. RESULTS: Workers were exposed to a mean noise level of 105.5 dB. As many as 27.6% of them complained of tinnitus and the majority suffered from some degree of hearing loss in either ear, but none of them exceeded 60 dB. Audiometric notches were detected in either one or both ears. Only 28.6% of workers showed the absence of notches. The TT genotype of IL-1ß polymorphisms was dominant in 49% of the workers, whereas TC was predominant in 39.8% and CC in 11.2%. The CC genotype was associated with smoking (54.5%) and audiometric notches (100%). The IL-1ß genotype distribution showed no significant difference with or without tinnitus. CONCLUSION: This study showed an association between the CC genotype and smoking as well as audiometric notches in workers occupationally exposed to noise. Workers showing audiometric notches should be followed up regularly. Further studies are required to confirm the interrelationship amongst tinnitus, audiometric notches, and IL-1ß genotypes.

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Noise exposure has been commonly regarded as the main hazard of occupational hearing loss. Recent studies indicate that several chemicals, including organic solvents have ototoxic effects. This study aimed at evaluating the hearing of workers exposed to both noise and a mixture of organic solvents at concentrations anticipated as safe. The study comprised three groups. The first one included 70 workers exposed to noise only, the second group consisted of 93 workers exposed to organic solvents and noise, and the control group included 59 individuals exposed to neither noise nor organic solvents. The three groups were matched for age, socioeconomic status, and smoking habit. The results of this study revealed that there was no statistically significant difference between the two exposed groups as regards the duration of exposure. There was a highly statistically significant difference between the two exposed groups as regards the different types of hearing loss (conductive deafness, sensory neural hearing loss, and mixed type) compared with the control one. Our study reported that sensory neural hearing loss occurred earlier in subjects with combined exposure to noise and solvents at a mean duration of exposure (16.38 ± 9.44 years) compared to (24.53 ± 9.59 years) the subjects with sole exposure to noise. The difference between the two groups was statistically significant regarding this type of hearing impairment (p < 0.05). There was a positive significant correlation between hearing impairment and duration of exposure in the two exposed groups. As regards the results of the environmental monitoring, both noise exposure levels (dB) and levels of different organic solvents measured (mg/m(3)) in different work departments were less than the levels recommended by Egyptian Environmental Law No. 4 for 1994. It is recommended that in the case of combined exposure, noise and solvent levels should be lowered than the permissible limits recommended for either alone.

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