[Are the cobalt hip prosthesis dangerous?]. / Les prothèses de hanche au cobalt sont-elles dangereuses ?

The placement of a hip prosthesis is one of the most common orthopedic surgical procedures. Some implants contain metal and are therefore capable of releasing metal particles like cobalt in patients who wear metal prostheses. Cobalt can be responsible of local toxicity (including metallosis, hypersensitivity reaction, and benign tumor) or systemic toxicity (including cardiomyopathy, polycythemia, hypothyroidism, and neurological disorders). To monitor potential toxicity of metal hip prostheses, an annual monitoring of patients implanted is recommended and includes clinical examination, radiological examination and blood cobalt determination. The cobalt concentration in blood allows to estimate the risk of toxicity and to evaluate the performance of the implant. The currently recommended threshold value is equal to 7 µg of cobalt per liter of blood. Our study, conducted on 251 patients over a period of 4 years, has shown that the cobalt concentration average was 2.51 µg/l in blood, with 51 patients having a cobaltemia higher than the threshold of 7 µg/l.

[Biomonitoring of exposure to chemical products in environmental and workplace toxicology]. / La surveillance biologique de l'exposition aux produits chimiques en toxicologie industrielle et de l'environnement.

Biological monitoring, also called biomonitoring, is a process to prevent and assess health risk for individuals exposed to chemical products present in environment or through workplace exposure. Biomonitoring is most often a monitoring of exposure or of effect. The exposure monitoring is currently the most widespread in toxicology. It involves the determination in biological fluids of different biomarkers, most of which are biomarkers of internal dose. These biological indicators are typically measured in blood and urine, but other biological samples can be analyzed. They are used to assess the penetration of environmental pollutants into the body. Assay results are interpreted in relation to reference values which are adapted either to occupationally exposed populations, or to general population. This interpretation and the choice of appropriate biomarker of exposure are not always obvious. Biomonitoring has some limitations despite its many advantages. It is complementary to another health prevention approach: the monitoring of ambient air. To illustrate in practice the biomonitoring of exposure, several examples of toxics and their associated biomarkers are reviewed: benzene, toluene, styrene, polycyclic aromatic hydrocarbons, chloroform, 2-hexanone and hydrogen cyanide.