Richard A. Hanson © 2004
Foreword: Usually my ramblings take on a humorous tone, but there is nothing funny about being poisoned. With that in mind, I will try to pass on to you some of the things I have learned in over 30 years of dealing with chemicals. According to “Casaretti and Doull’s Toxicology: The Basic Science of Poisons,” “All substances are poisons; there are none which are not a poison. Yet on a daily basis we expose ourselves and others to a myriad of toxic substances as if we were honor graduates of the “Scratch and Sniff School of Chemistry”. Repetition does not equal right, just because we have done certain things with chemicals before and got away with it, does not mean that there are not adverse consequences associated with our behavior. In addition to poisoning yourself, you also may be bringing toxic substances home from the shop and sharing them with your families and children. We seem to operate on the premise that if it don’t blow up in our face and kill us on the spot the first time, whatever we are doing must be safe and acceptable but all the while we are trying to stifle that little annoying nagging voice in the back of our minds that is screaming “what the heck are you thinking”. There are Governmental Regulations that dictate safe practices when handling chemicals in the workplace, but since most of us in the Blacksmithing Community are either hobbyists or a self employed single person operation, we do not fall under the requirements of these regulations. That doesn’t mean we have to be unaware, uninformed and unprotected. If you choose to be, that is your prerogative but give a little thought to who will provide for your family if you are unable to work because of illness or death. It is said that ignorance is bliss, but in this case what you don’t know can hurt you.
The three factors that determine what effect a toxic substance will have on the human body are:
1. Dose: The concentration and quantity of the chemical to which you were exposed.
2. Duration: How long were you exposed.
3. Route of Entry: How did the substance enter the body.
Routes of Entry: There are four routes of entry for a toxic substance to enter the body:
1. Inhalation – where be breath in the vapors, fumes or finely divided particles of the substance. Once the toxic substance has entered our respiratory system, it can cause us harm in a number of ways. Either damaging the respiratory system itself, or by passing through the lungs and into the blood where it can either affect the blood or other organs of the body.
2. Ingestion – where the substance enters our body via the mouth. We don’t usually go out and taste toxic substances, but I have witnessed people putting their finger into a substance thought to be antifreeze and tasting it. Most cases of poison by ingestion are caused by poor personal hygiene habits, i.e. failing to wash our hands and face after leaving the shop and before eating or drinking. Eating and drinking in the shop area. And also by smoking or chewing tobacco without washing your hands. We get our fingers into everything from pie to poison and the next thing you know then end up in our mouth and rarely do they go through soap and water first.
3. Absorption – where the substance contacts the skin and either damages the skin at the point of contact or is absorbed directly through the skin and passes into the blood stream where it can travel throughout the body and damage other organs.
4. Injection – no one I know of has loaded a syringe full of poison and gave himself a shot, but in our work environment there are numerous sharp things with which we come in contact. If a sharp object is contaminated with a toxic substance and it penetrates the skin, you have just been injected. This is probably the least common way of chemical poisoning, but it is probably the most common way of developing a galloping infection that takes massive doses of antibiotics to cure.
Personal Protective Equipment: You don’t have to spend a fortune on PPE, but every shop should be equipped with the minimum necessary to afford adequate protection. The first thing in your PPE arsenal should be information. Get a Material Safety Data Sheet for every chemical in your shop. You will probably balk at this and think you don’t need ones for the stuff you deal with on a daily basis. You are wrong! Did you know that there are at least 4 different carcinogens in gasoline. Get a MSDS for every chemical in you shop, put them in a 3 ring binder and then READ the MSDS before you handle the chemical. The MSDS cannot protect you if it is sitting on the shelf collecting dust. Remember that welding rods have chemicals in them so get a MSDS for them too. All you have to do to get one is ask for it when you purchase any material.
Next read the label on the container. They usually list some of the ingredients, but not always and usually have some safety precautions for handling and using the chemical. Remember that chemical companies are in the business of selling chemicals, not providing for your safety and well being. When regulations on use and disposal of
Once you are informed of the nature and hazards associated with the substances you use, it will be easy to assemble the minimum PPE that is necessary to protect yourself. This should include the following:
1. Respirator – either full face or half face. Remember that one size does not fit all. When you purchase the respirator, have the supplier give you a fit test to determine what size fits you the best. You will also need filter cartridges what cartridges are necessary will be determined by what are dealing with. You may need several sets of cartridges to protect you from an array of chemicals. Clean the respirator and store it and cartridges in a tightly sealed plastic bag when not in use. This will keep it clean and help to extend the life of the cartridges. Replace cartridges when you began to smell contaminant through them or you notice it has become difficult to breathe through them.
2. Rubber Gloves and Apron – if you are handling and working with corrosive materials, this is a must. When I say rubber, what you will probably end up with is some man made fiber, but be sure to tell your supplier what materials you expect the equipment to protect you from.
3. Chemical Splash Goggles – these differ from goggles meant to protect you from flying objects in that they have indirect venting that does not allow liquids to enter through the vents.
4. Soap and Water – a great amount of chemical contamination can be eliminated if we simply wash our hands and face before eating or drinking anything and when we leave the shop for the day.
Effects of Chemical on the Body:
1. Acute - exposure to high concentrations of a chemical over a short period of time where there is rapid onset of the symptoms of chemical exposure the symptoms usually dissipate after the+ person is removed from the source of exposure. This is not to say that acute exposure cannot be life threatening, depending on the chemical, one acute exposure can be fatal.
2. Chronic – exposure to chemicals over a long period of time where symptoms chemical exposure do not manifest themselves immediately. The chronic effects sometimes take years to develop. Chronic effects can be accumulative, and exposure to certain chemicals can have both an acute and chronic effect on the body.
Systemic Toxicity: Exposure to a toxic substance can produce a local effect, or have a systemic effect. An example of a local effect would be skin contact with a corrosive material. The material burns the skin at the point of contact. If quick action is taken and the corrosive removed or neutralized, the effect would be a localized burn. If prompt action is not taken, the material can penetrate the skin and enter the blood stream or cause other internal damage. This would be considered a systemic effect.
The individual physiological systems of the body can be adversely affected in several ways. When a toxin adversely affects the human body, it does so in one or more of the following ways:
1. Pulmonary Toxins: These substances affect the respiratory tract. From a basic point of view, a pulmonary toxin is an asphyxiant. Asphyxiants can be broken down as either as either simple asphyxiants or chemical asphyxiants. A simple asphyxiant displaces the oxygen in the air and causes injury to the body by oxygen deficiency. Chemical asphyxiation occurs with the actual destruction of the cells within the lungs. This leads to fluid buildup within the lungs which is referred to as pulmonary edema.
2. Hemotoxins: These are a broad category of toxins that affect the circulatory system. Certain toxins can inhibit the ability of the blood to absorb oxygen and transport it within the body. Other toxins adversely affect the white blood cells or they can attack the bone marrow where red blood cells are produced. Others actually destroy red blood cells and some affect the electrolyte balance.
3. Neurotoxins: These affect the central nervous system and peripheral nerve cells. Neurotoxins can inhibit operation of the central nervous system by binding to a certain part of a nerve cell or some actually destroy nervous system cells. Eventual death from the effects of exposure is a possibility.
4. Receptor Toxins: These affect specific “target organs” or systems within the body. These would include:
A. Hepatotoxins: Chemicals that can cause damage to the liver
B Nephrotoxins: Chemicals that have a toxic effect on the kidneys.
5. Cytotoxins: Chemicals that adversely affect anything they come in contact with. i.e. corrosives.
6. Teratogens: Adversely affect the development of the fetus. i.e. Organic Mercury Compounds.
7. Mutagens: Cause changes in the genetic materials n the nucleus of cells in a way that can be transmitted during cell division. These substances can cause a mutation. i.e. Benzene, Ethylene Oxide and Hydrogen Peroxide.
8. Carcinogens: Substances that are capable causing tumors. Substances that cause cancer. The effects of exposure to these substances may not appear for years.
Hazards of Various Chemicals: At last count there were in excess of 25,000 chemicals that were known to be hazardous to humans. There is no way that I could possibly list all of them along with there hazards so I will attempt to list some of the more common chemical families and the general hazards associated with them. Keep in mind however, that there will be other hazards associated with some specific chemicals in addition to those listed for a specific chemical family.
Hydrocarbons: All hydrocarbons are central nervous system depressants. That is when they enter the body they produce an anesthetic effect. They put the brain to sleep. You are all probably aware that ether (a hydrocarbon) has long been used as an anesthetic. Ethyl alcohol, i.e. Jack Daniels Bourbon, is also a hydrocarbon and you are well aware of the effects it has on the human body. In addition to the anesthetic effect produced by these substances, many chemicals in this family are carcinogens the BTEX group, Benzene, Toluene, Ethyl Benzene and Xylem, are prime examples of this. All of the preceding 4 chemicals can be found in gasoline.
Primary routes of entry for hydrocarbons to enter the body are inhalation and skin absorption with the exception of ethyl alcohol where ingestion is the preferred route of entry. In addition to effects on the central nervous system, exposure to hydrocarbons can have detrimental effects on various other organs of the body including the kidneys, liver, heart, lungs and blood.
Chlorinated Hydrocarbons: In addition the effects on the central nervous system mentioned above, nearly all Chlorinated Hydrocarbons are carcinogens. Additionally depending on their makeup, they have adverse effects on other organs of the body, usually the liver or kidneys. Carbon Tetrachloride targets the kidneys while
Primary routes of entry are inhalation and skin absorption. Some common sources of Chlorinated Hydrocarbons are brake cleaner, electrical contact cleaner, penetrating oil and paint remover.
Dust: Dust is a common hazard that is overlooked by most of us. Dust particles that are less than 5 micron in size penetrate to the deepest part of the lungs where they damage the alveoli. Dust particles in this size range include coal dust, silica dust and asbestos particles. In addition, the dust from sanding various woods is toxic to some people. For example Cocobolo and some horn materials that are used as handle material by knife makers. In addition, dust or sandings from heavy metals can be
The only route of entry for dust that is of any consideration is by inhalation. Dusts can also enter the body by ingestion if eating and or drinking is allowed in the work area.
Heavy Metals: Heavy metals, especially Lead, Zinc, Nickel and Cadmium are extremely toxic to the human body. Arsenic, another heavy metal which is more rarely found is a deadly poison. The greatest hazards faced by blacksmiths from these substances is the breathing of the fumes from the molten metals when welding or soldering. Lead is the basic ingredient in solder. Lead free solders may contain Cadmium as may certain types of welding rod. Arsenic is commonly used in treating wood to make it insect and rot resistant. Keep that in mind the next time you are looking for kindling to start the fire in your forge.
In addition to the hazards listed above, Nickel is also a sensitizer which upon repeated exposure can cause an asthma like reaction if inhaled
Common routes of entry are inhalation of the fumes from the molten metals and to a lesser extent, ingestion of metal dusts by eating, and drinking in the work area.
Isocyanates: These are an extremely toxic group of chemicals they are usually found as the catalyst in two stage paints such as DuPont Emron. They are respiratory system sensitizers. While this may sound rather benign, it can be deadly. As a person is exposed to these chemicals, the respiratory system becomes sensitized to the chemical. This may be as a result of one acute exposure or to several repeated exposures. Sensitivity varies with the amount of exposure and the individual. Once the respiratory system becomes sensitized, any further exposure will produce an allergic reaction that may be as mild as symptoms of a cold to as severe as anaphylactic shock and death.
Route of entry is inhalation.
Acids: Acids are used for various processes when working metals, among them are pickling metal to remove the scale, etching Damascus blades to bring out the pattern and in some cases, quenching the metal to harden it. When one thinks of acids, the most immediate hazard that comes to mind is that of it’s corrosiveness to skin there are other hazards associated with these materials that are less well known. The fumes from acids can damage the respiratory tract. Some like Hydrofluoric Acid, which is found in aluminum brightener, will give a mild corrosive burn to the skin at the point of contact, penetrate the skin and go directly to the bones it leaches the calcium out of the bones. Washing with water will not remove this acid once it has penetrated the skin. An ice cold solution of a chemical called Zepherin is needed to neutralize this type of acid. In addition, with large burns from this acid, the solution may have to be injected to effect neutralization. Other hazards of acids include the formation of toxic and or flammable gases when in contact with certain other substances in addition they may form explosive compounds when mixed with the right chemicals. They can also cause spontaneous combustion when mixed with certain other materials. Many acids are more powerful oxidizers than pure oxygen.
Primary routes of exposure are inhalation of the vapors and skin contact.
Bases: Like acids, bases are used in various metal working applications either to clean metals or to produce various patinas on certain metals. Bases like acids can be corrosive to the skin.
Primary routes of entry are inhalation of the vapors or fumes or skin contact.
Gases: Generally in metalworking we deal with 3 different types of compressed gases.
1. Flammable Gases: Two of the more common gases associated with metalworking are Acetylene used for welding and cutting operations, and Propane or LPG used as fuel for forges as well as in welding and cutting operations. In addition to the obvious flammable hazard inherent with these gases, they can displace the oxygen in the air and cause asphyxiation. A few words of caution about Acetylene are never enough. This gas is decidedly unstable. In fact it is so unstable that it is dissolved under pressure in Acetone in the cylinder to keep it from exploding. It is flammable in air in concentrations from 2.5% to 100%. Another hazard of this gas is its’ ability to deteriorate the hoses of the welder. If the tank is not shut off and the hoses drained it can cause the hoses to deteriorate. If this happens when the shop is unattended, the entire contents of the tank can be leaked into the shop. When the shop is reoccupied, the first person to make a spark or turn on a light switch gets to play “Mr. Roberts does Hazmat”. “Hi boys and girls can you say KABOOM?” “Can you say butt first through the wall?”
2. Non-Flammable Gases: Various Non-Flammable gases are used as shield gases in welding. The most common are Carbon Dioxide (CO2) Argon, Nitrogen and Helium. Some shield gases are a mixture of two or more of the fore mentioned gases. The primary hazard of these gases is that they displace the oxygen in the air. They are odorless and can collect in confined spaces or poorly ventilated areas and cause asphyxiation. One or two breaths in an oxygen deficient atmosphere is usually enough to cause unconsciousness.
3. Oxidizers: Oxygen used in welding and cutting operations is a powerful oxidizer. While it does not burn, it causes other materials to burn with savage intensity. Nomex, a flame retardant material used in firefighter clothing, burns like a gasoline soaked rag in an oxygen enriched atmosphere. Exposure to pure oxygen can cause some materials to spontaneously combust. Other chemicals not normally thought of as oxidizers are much more powerful oxidizers than pure oxygen. Nitric Acid and Sulfuric Acid are extremely powerful oxidizers. Some of the Halogens, (Chlorine and Fluorine for example) while containing no oxygen are extremely powerful oxidizers in addition to being poison gases. They will cause things that do not normally burn to ignite and burn, or form explosive compounds when mixed with other chemicals.
Primary route of entry for gases is inhalation although the high pressure hazard should not be ignored. Gas under pressure can be injected through the skin.
Poisons: Some of the common poisons found around the average shop or garage are insecticides. Most of us are well aware of their inherent hazards and exercise some degree of caution when using and handling them. It is the less than obvious poisons that you need to worry about. I once saw a can of penetrating oil that listed only two ingredients, Carbolic Acid and