Health damage from noise exposure
Explore the impacts of noise on worker health, including hearing loss, cardiovascular effects, and risks for pregnant women, as well as interaction with other agents.
· 7 minutos · Segurança no Trabalho
Excessive noise in workplaces is a significant concern for occupational safety and health. Prolonged exposure to high levels of noise can lead to various pathologies, directly impacting workers' well-being.
It is fundamental that workstations are evaluated and adapted to mitigate the risks associated with noise, thus ensuring the protection of employees' health. Specific health monitoring of exposed workers is crucial for the prevention and early detection of any adverse effects.
Noise legislation is governed by Decree-Law no. 182/2006, which establishes the minimum safety and health requirements regarding workers' exposure to risks due to noise.
Factors influencing injuries from noise exposure
Several factors contribute to the severity of damage caused by noise exposure:
- Noise intensity: Refers to the energy of the sound wave. Higher intensity levels increase the potential for damage.
- Exposure time: The adverse effect of noise is directly proportional to the duration of exposure. The longer the exposure time, the greater the total sound energy absorbed by the inner ear.
- Noise frequency: The hair cells of the inner ear, more susceptible to the harmful action of noise, are responsible for perceiving frequencies between 3000 and 6000 Hz.
- Nature of noise: Intermittent exposure is less damaging than continuous exposure. However, permanent noise causes less injury than impulsive or impact noise, of identical intensity, due to the middle ear's muscular damping capacity.
- Individual susceptibility: Factors such as age, middle or inner ear diseases, neurological pathologies, and family history can increase individual vulnerability, although they are difficult to quantify:
- Age: There is a higher probability of injury in middle age, often aggravated by presbycusis (progressive age-related hearing loss).
- Middle ear diseases: Conductive hearing loss (a decrease in hearing sensitivity caused by an alteration that prevents sound transmission from the outer and middle ear to the inner ear) can lead to greater damage, as the middle ear loses its protective function.
- Inner ear diseases: The fragility of the cochlea (spiral structure in the inner ear) in cases of sensorineural hearing loss (damage to hair cells) increases the risk.
- Neurological diseases: A history of meningitis or traumatic brain injury has been associated with deafness.
- Family history: Genetic predisposition to early deafness or hereditary diseases can influence susceptibility.
Hearing damage caused by noise exposure
Exposure to noise can lead to several types of hearing damage:
- Difficulty hearing: In noisy environments, it becomes difficult to hear other sounds or people.
- Auditory fatigue: Temporary reduction in hearing capacity after noise exposure, which reverses with sound rest, without permanent organic injury.
- Permanent hearing loss: Irreversible sensorineural hearing deficit that begins at frequencies of 3000 to 6000 Hz, with injury to the organ of hearing. Initially, it does not affect conversational frequencies, but with continued exposure, the loss spreads, causing communication difficulties and disability.
Noise exposure and cardiovascular effects
There is a slight association between noise exposure and an increased risk of arterial hypertension, cardiovascular diseases, and mortality from these diseases.
Noise exposure and effects on pregnancy and the fetus
Although the evidence is limited, there may be an association between noise exposure and low birth weight. It is suggested that if a pregnant woman with occupational noise exposure presents a fetus with low weight for gestational age, noise exposure should be avoided. From the 20th week of pregnancy, it is advisable to avoid occupational noise exposure for pregnant women to prevent possible effects on the newborn's hearing.
Noise and chemical agents
The combination of noise with certain chemical agents can aggravate hearing damage:
- Ototoxic solvents: The combined action of noise with styrene and toluene has been shown to be harmful to hearing. There is no conclusive evidence for other solvents.
- Asphyxiant chemical agents: The combined action of noise with carbon monoxide can cause hearing damage. There is insufficient data for other asphyxiants such as hydrogen cyanide.
Health surveillance is recommended for workers exposed to noise who are also exposed to toluene, styrene, or carbon monoxide, with more rigorous monitoring of auditory effects and the application of preventive measures to avoid combined exposure.
Noise and tobacco
Knowledge about the effects of combined exposure to noise and tobacco on hearing is limited. It is suggested to record tobacco consumption in workers exposed to noise and to provide smoking cessation counseling, as part of health surveillance.
Noise and physical agents
An increased risk from combined exposure to noise and vibrations in general is not demonstrated. However, for workers who use portable vibrating tools in noisy environments and who develop vibration white finger syndrome, there is a greater risk of hearing loss. Health surveillance should include the assessment of hand-arm vibration exposure, with follow-up of those suffering from vibration white finger, and suggest preventive measures in case of auditory effects.
Noise and pharmaceuticals
Studies on the interaction between noise and ototoxic drugs are scarce, focusing mainly on short-term effects with acetylsalicylic acid. However, the combination of noise with certain antibiotics (aminoglycosides such as gentamicin, kanamycin, and neomycin) and cytostatics (cisplatin) can potentiate hearing damage.
Monitoring exposure to these drugs is recommended for workers exposed to noise. If a worker exposed to noise needs treatment with these medications, existing prevention measures should be reinforced, and more rigorous monitoring of auditory effects should be implemented.