January 31, 2008

The excessive noise found in the main cities of Mexico and the improper use of certain antibiotics are seen as the main reasons for an increase in the number of hearing impaired Mexicans.

According to reports, the maximum permissible daytime noise level in Mexico City is 68 dB, and between 8 pm and 6 am noise levels may not exceed 62 dB. However, sources say, these levels are routinely surpassed.

Young people severely affected

A study carried out in a suburban area of Mexico City measured the noise levels in two schools, two manufacturing plants, a shopping centre and a block of flats. Researchers found noise levels between 90 and 100 dB, surpassing the noise level limits at any given hour on any given day.

The effects on local residents were studied, as well, with 135 subjects aged 15 to 49 years screened for hearing disorders. Researchers found 35% of the study’s participants suffered from severe hearing damage with the 15 to 29 age group appearing more severely affected by hearing damage.

Researchers concluded the higher incidence in the youngest group may be due to unrestrained use of personal stereos. More and more people try to drown out the background noise by listening to music on their MP3 players, increasing the risk of suffering from hearing loss.

The study was headed by Graciela Meza Ruiz, a specialist in biochemistry of the ear at the Cellular Physiology Institute at UNAM.

Misuse of antibiotics

Improperly used antibiotics constitute another significant risk factor, according to research. Under Mexican law, any adult can obtain antibiotics without medical prescription.

“Any antibiotic coming into the human body damages the ear”, says Graciela Meza Ruiz, who was also in charge of a study of the relation between hearing loss and certain antibiotics.

Meza Ruiz found a hereditary mutation in patients with tuberculosis. The antibiotics used in this population made them more likely to suffer from severe hearing loss and deafness.

Source: el universal.com.mx