In many countries, regulations requiring the monitoring of human mercury exposure levels are becoming increasingly stringent. In this study, mercury exposure among Pakistani city dwellers was assessed by means of hair mercury analysis. Specifically, we used cold-vapor atomic absorption spectrometry to measure hair mercury concentrations in 291 adult subjects (136 males and 155 females) residing in 6 major cities of Pakistan. A questionnaire was used to obtain information about biological and lifestyle characteristics of the subjects. Most of the subjects had low hair mercury concentrations (median, 0.35 μg/g) and were therefore not at significant health risk due to mercury exposure; however, some subjects had excessive hair mercury concentrations (up to 565 μg/g). The use of skin creams and soaps was found to be a major contributor to excessive hair mercury concentration. In addition, among the subjects who did not have excessive hair mercury concentrations, frequency of fish consumption, smoking, city of residence, and education level were also minor but statistically significant contributors to hair mercury concentration. Our results suggest that the use of mercury-containing personal care products (particularly skin creams and soaps) among Pakistani city dwellers was the main significant source of exposure to mercury.

The aim of the present study is to investigate the protective effect of chelators against the decline of ependymal ciliary beat frequency (CBF) in mice induced by methyl mercury (MeHg). CBF decreased after mice were given MeHg (20 mg/L) in drinking water for eight days. When dimercaptosuccinic acid (DMSA) was injected subcutaneously once a day from Day 6 to Day 8, CBF recovered from the decrease that was found in MeHg-drinking mice, but the other mercury chelators had no effect. The mercury contents in blood, the cerebrospinal fluid and the frontal lobe decreased after the DMSA treatment in comparison with the group that was only given MeHg, but the decrease did not depend on the dose of DMSA. In addition, CBF decreased during Day 3 to Day 5 after the single intraperitoneal injection of MeHg. However, the CBF did not recover in spite of a single injection of DMSA three days after the MeHg injection. Next, a brain slice prepared from healthy mice was set on a glass-bottom dish and artificial cerebrospinal fluid (CSF) was circulated. When MeHg was added to the CSF, CBF decreased. However, the addition of DMSA in the dish did not suppress the decrease of the CBF induced by MeHg treatment. In conclusion, these results may suggest that MeHg does not affect genes involved in the ciliary movement but influences the substances related to the movement.