Toxicologie environnementale et analytique

Cadmium (Cd) is a ubiquitous environmental pollutant of increasing worldwide concern. It is thought to be of greater concern to rapidly industrializing developing countries because of the increasing pace of industrial activities in these countries with increasing consumption and release into the environment. Traditionally, health concerns in exposed human populations have revolved around the association of Cd with bone disease, emphysema and possibly hypertension. Accumulating evidence suggest that Cd is involved in the disruption of many genomic processes, the mechanisms of which are being gradually understood. Changes in DNA methylation may be induced by cadmium leading to epigenetic alterations. Additionally, though Cd is not thought to induce Reactive Oxygen Species (ROS) directly because it is not capable of accepting or donating electrons under physiological conditions, 8-hydroxy deoxyguanosine (8-OHdG) (a marker of oxidative stress to DNA and a risk factor for cancer among others) has been shown to be elevated in the DNA of testes from rats treated with cadmium chloride, at least in part because Cd inhibits DNA repair mechanisms. Cadmium is also a metabolic antagonist to Zinc (Zn), an important micronutrient involved in numerous molecular activities. This antagonism alters the physiological stoichiometric relationship between Cd and Zn leading to high Cd/Zn ratio, one consequence of which is high error rate and lack of efficient DNA repair systems leading to high mutation and genome instability culminating in many carcinogenic states, particularly prostate carcinogenesis. Cadmium has also been shown to replace Zn in the tumor suppressor protein, p53 thereby impairing p53’s DNA binding activity and associated repair processes. The expression of the p53 protein is significantly depressed by cadmium. Although the rising level of Cd in the environment is widely acknowledged, the occult threat it poses to genome stability largely through inhibition normal DNA damage repair, oxidative stress, apoptosis and health is poorly recognized. This paper examines the involvement of Cd in the molecular pathways of human disease, providing insight for the prevention of genome instability and associated disease susceptibility particularly cancer across populations through micronutrient intervention, aiding upregulation of the antioxidant defense and DNA repair systems.

This study was performed to identify and count both asbestos and non-asbestos fibers during brake manufacture in Iran. A total of 56 respiratory air samples of personnel were measured by phase-contrast microscopy (PCM) and scanning electron microscopy (SEM). The fiber type and its chemical composition were also evaluated by SEM and energy-dispersive X-ray analysis (EDX). Monitoring of total fiber levels demonstrated that its ranges are from 0.23 to 1.50 PCM f/ml. The geometric mean and standard deviation of the airborne asbestos and non-asbestos fiber concentrations were 0.22(1.61) and 0.32(1.61) SEM f/ml respectively. The observed asbestos fiber concentrations in many processes were higher than the threshold limit value (TLV) which is proposed by American Conference of Governmental Industrial Hygienists (ACGIH), as equal as 0.1 f/ml. Based on these findings, the geometric means of the non-asbestos concentrations were considerably lower than TLV of the ACGIH which is 1 f/ml. The SEM data exhibited that fibrous particle consists of chrysotile (40%) and rock wool (60%). It can be concluded that more than 50% of airborne fibers inhaled by the workers were rock wool with fibers greater than 1 μm in diameter. For evaluation of airborne fibers, the PCM method was not able to detect the fibers lower than 0.25 micrometer. This study demonstrated that SEM technique methods are essential elements for accurate characterization of mineral dusts, particularly when dealing with large number of samples.

The bivalve shellfish Pinctala radiate is a popular edible food for Alexandria local communities. In an attempt to track the quality of marine water of two different locations along Alexandria coast of Egypt, we measured the RNA/DNA ratio and acetyl cholinesterase (AChE) activity in the haemolymph of this organism. The study showed an average ratio for RNA-DNA of 3.3, arranged as follows; 4.34 at El-Max > 2.8 at Miami localities. These results suggest that the coastal water of Alexandria is considered as unpolluted with examined insecticides in this research.

Thirty two samples were collected of milk powder for baby and human consumption and Basaa fish 8 infant milk formula, 8 growing up milk formula purchased from pharmacy in Saudi Arabia, 6 Sweetened Full Cream Milk Powder purchased from China and 10 fish samples (Basaa fish) Ui Tnam purchased from popular markets in Saudi Arabia. The samples were analyzed and determination for Melamine (MEL) by HPLC/DAD. The incidence of MEL in powder milk and in fish, was about 100 and 80 % respectively. High concentrations were found in growing up milk formula. Melamine was detected in 28 out of 32 samples with varying concentrations. Of the 28 melamine positive samples, samples had a melamine concentration higher than 258 mg/kg (the median). The lowest and the highest concentrations were found to be 7.5 and 258 mg/kg, respectively in all samples. This application note describes an efficient and simple method for preparing milk powder and fish samples coupled to an HPLC/DAD method for rapid analysis of melamine in these samples. The purpose of the survey was to determine levels of melamine and to monitor the effectiveness of the controls in place to limit consumer exposure to melamine.