Disorders Caused by Ionizing Radiation and Organic Solvents,etc

Disorders Caused by Ionizing Radiation

How does radiation affect the human body?

Ionizing radiation is radiation with enough energy to remove electrons from atoms, creating ions. Ions made by this ionization effect react with molecules (e.g., water) that make up the human body to form active ions called free radicals, which induce cellular DNA (deoxyribonucleic acid) damage.

Most of the DNA damaged by free radicals is restored to its original structure immediately. However, some damaged DNA is left unrepaired or anomalies occur during the repair process. If DNA damage causes lethal cell injury, cell death by apoptosis may occur, leading to clinical radiation injury. In addition, DNA damage can potentially cause cancer.

Special Medical Examination(Ionizing Radiation)

Users of radioactive substances are obliged to undergo the Special Health Examinations (Ionizing Radiation) once a year, under the Ordinance on Prevention of Ionizing Radiation Hazards and the Radiation Hazard Prevention Act. Those who will use radioactive substances for research, laboratory work, etc., and those who are directed to undergo the special health examinations by occupational health physicians based on the results of the regular personal dosimetry measurements, should undergo the Special Health Examinations.

Disorders Caused by Organic Solvents and Specified Chemical Substances

Organic solvents and specified chemical substances cause various disorders in the human body. These arise in the following way:

1)　They adhere to the skin or mucous membranes (eyes, respiratory organs, digestive organs) and act at these sites
2)　They are absorbed by the skin or mucous membranes, circulate through the body, and immediately cause disorders (acute symptoms)
3)　Long-term repetitive absorption causes the substances to accumulate in specific organs (target organs), causing damage (chronic symptoms)

Adhesion to and absorption by the skin and eyes

Organic solvents and specified chemical substances cause skin disorders. They penetrate the skin, which may lead to pain, erythema, or blistering. Furthermore, if they get into your eyes, they can cause watering (shedding tears), inflammation, or pain. Organic solvents and specified chemical substances that are absorbed by the skin enter the bloodstream through the capillaries. Toxic substances that dissolve more easily in water or oil will be absorbed faster. Moreover, they will be absorbed more easily by the skin if you are wounded.

Pay particular attention to the following substances that are absorbed by the skin:

Carbon tetrachloride, 1,1,2,2-tetrachloroethane, carbon disulfide, toluene, xylene, isobutyl alcohol, cresol, 1,4-dioxane, N,N-dimethylformamide, tetrachloroethylene, 1-butanol, methanol, methyl isobutyl ketone, and methylcyclohexanone

Inhalation and absorption by the respiratory system

　If you inhale gases or vapors, they will pass through the nasal cavity, pharynx, larynx, trachea, bronchial tubes, and alveolar ducts. Depending on the type, they may cause irritation along the airway. Once they reach the alveoli, many organic solvents and specified chemical substances will enter the bloodstream together with the oxygen that is being absorbed.

Absorption by the digestive system

Toxic substances that have been swallowed enter blood vessels called portal veins from the stomach and intestines, and are carried to the liver where they are mainly metabolized. However, if your liver is underfunctioning or if the amount of organic solvent or specified chemical substance absorbed is too great for the liver to metabolize, it will be released into the bloodstream.

Neurological damage

Organic solvents and specified chemical substances cause neurological-(or space) damage. Symptoms that the central nervous system may be affected include headache, dizziness, memory loss, vision loss, dystonia, finger tremors, fainting, and psychoneurotic symptoms (anxiety, short-temper, impatience, insomnia, enervation, etc.). Brain wave tests, ophthalmological findings, psychiatric testing, etc., are useful to judge whether or not there is neurological　damage. Toluene is dangerous, and people may have fainted and died after playing with paint thinner of a certain amount or more. Symptoms of damage to the peripheral nervous system include numbness, pain, atrophy, and weakness of muscle in the extremities, but multiple neuritis is seen in the case of n-hexane. To determine this, electromyograms, peripheral nerve conduction velocity tests, quantitative measurements of vibratory sensation, etc., are useful. Symptoms of damage to the autonomic nervous system include fainting, dizziness, abnormal sweating, and sensitivity to coldness for circulatory system disorders, and constipation, nausea, epigastric pain, loss of appetite, and stomach symptoms for digestive system disorders.

Exposure to the following require neurological exams (when deemed necessary by a medical doctor):

toluene, xylene, or carbon disulfide

Exposure to the following require exams for optic nerve disorders (when deemed necessary by a medical doctor):

methanol or methyl acetate

Exposure to the following require neurological exams for the peripheral nerves (when deemed necessary by a medical doctor):

n-hexane

Hematopoietic disorders

Toluene, xylene, n-hexane, and benzene can cause hematopoietic disorders such as anemia. Initially, no symptoms are present, but as they progress, symptoms such as dizziness and disorientation will arise.

Liver damage and biliary tract disorders

Many organic solvents and specified chemical substances are broken down in the liver, but this can lead to liver damage. Initially, no symptoms are present, but as it progresses, symptoms such as fatigue and nausea will arise.

Exposure to the following require liver function tests (when deemed necessary by a medical doctor):

Chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,2-dichloroethylene, 1,1,2,2-tetrachloroethane, chlorobenzene, ortho-dichlorobenzene, trichloroethylene, tetrachloroethylene, or N,N-dimethylformamide

Exposure to the following require biliary tract tests (when deemed necessary by a medical doctor):

Dichloromethane, vinyl chloride, 1,2-dichloropropane, etc.

Kidney damage

As it progresses, symptoms such as edema and increase in blood pressure will arise.

Exposure to the following require kidney function tests (when deemed necessary by a medical doctor):

Chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,2-dichloroethylene, 1,1,2,2-tetrachloroethane, chlorobenzene, ortho-dichlorobenzene, trichloroethylene, tetrachloroethylene, or N,N-dimethylformamide

Safety precautions

Who is in charge?

Know how to work with organic solvents and decide who will be responsible overall for health management and environmental management. Have reporting procedures in place for when accidents and injuries occur, as well as creating an environment in which these can be discussed, and suggestions for improvements to the working environment, etc., can be made at ease.

Know the names and the chemical and physical properties of the organic solvents that you are using

Get a Material Safety Data Sheet (MSDS) and read through it carefully, checking how to store the chemicals and the measures to take in an emergency.
The International Chemical Safety Cards (ICSC) provided by the International Program on Chemical Safety (IPCS) are also useful.
When an accident occurs, it will be helpful if the data sheet of the exposed organic solvent, etc., is brought to the hospital. Additionally, the person in charge must be familiar with the relevant laws and regulations, such as the Ordinance on Prevention of Organic Solvent Poisoning and the Ordinance on Prevention of Hazards due to Specified Chemical Substances.

Turn on the exhaust and ventilation systems

Be sure that you make it a habit to open windows and keep ventilation in mind, and do not let fumes from organic solvents fill the room. Use the fume hood when you are working with organic solvents.

Use protective equipment

Wear safety glasses, respirator masks, protective clothing, gloves, etc., for organic solvents and be sure not to be exposed to the chemicals.

Manage the amount of time spent working with organic solvents

There is a tendency for people to become absorbed in a task and work continuously. The person in charge must take the lead to devise working hours and methods that ensure no one spends long hours working with organic solvents.

Are the methods you have in place to store the organic solvents and dispose of liquid waste appropriate?

To prevent accidents and environmental pollution, organic solvents must always be stored appropriately and liquid waste must be disposed of properly. In addition to taking precautions within the laboratory, such as using bottles and labels with different colors, storing chemicals in locked cabinets at appropriate temperatures, and ensuring that the containers don't fall over in the event of earthquakes or fire, proper considerations must be given to the effects an accident could have on the entire university or research facility when managing organic solvents. When a new procedure will be performed, be sure to inform and consult the persons in charge of the facility.

Is the work area organized and clean?

To prevent accidents, the work area must be kept organized and clean at all times. Accidents can be prevented by all persons working in the laboratories ensuring that there are no fires, devices that could discharge electricity, inflammable materials, etc., left in the work area; no equipment are left in places where they can easily fall and their cables are not drawn across areas where people can easily trip over them; clothing, food, and books and items required for the experiment are not mixed; and the work area is kept organized and clean.