Opinion on Blog Posts

For our final blog post we were asked to write about if we felt blogging was an effective learning tool as opposed to classic exams. I think it was a very effective tool for learning some of the material. The blog posts still forced you to review the class material while conducting outside research online for each of the various topics we were assigned. It is also a tool that we could go back and look at as the semester went on if we wanted to review certain material. It was also very nice to not have to deal with the stress or pressure of exams. I feel that most people simply try to cram as much information as they can the week of the test then simply move on and forgot a majority of the material within a few weeks. I think this class was very enjoyable and am glad that I was able to take it during my last semester here at OU!

Heat Exhaustion vs. Heat Stroke

Heat exhaustion and heat stroke are both heat related illnesses that can have a serious impact on your health if not addressed. Growing up I worked as a lifeguard at our neighborhood pool for nearly 4 years. Before each summer began every lifeguard was required to attend re-certification classes where, aside from CPR, we were trained in how to handle first aid and how to address heat exhaustion and heat stroke. Thankfully I never encountered an individual undergoing an actual heat stroke but heat exhaustion is something I have had to address.

Heat exhaustion occurs after an individual has been exposed to high temperatures for a long period of time and is often accompanied by dehydration. High humidity or physical activity to someone not used to these conditions increases the likelihood of experiencing this ailment. Symptoms of heat exhaustion include confusion, sweating, rapid heart rate, nausea, dizziness, fainting, fatigue, headache, and dark-colored urine. Without intervention heat exhaustion can progress to heat stroke. The best way to treat heat exhaustion is immediately get out of the heat, rest, drink plenty of fluids, take a cool shower or bath, and find other cooling measures such as fans or ice packs.

As I previously mentioned, without intervention heat exhaustion can progress to heat stroke. Heat stroke is a much more serious condition and is considered a medical emergency as it can be life threatening if not treated immediately. Although is usually occurs as a progression from a less serious form of heat-related illness, it can strike suddenly especially as result of prolonged physical activity in high temperatures or with dehydration. Heat stroke is quite literally the failure of the body's temperature control system. It can not longer cool itself and internal body temperatures can rise above 105 degrees. It can result in brain damage and complications with the central nervous system within a very short period of time.

The most obvious sign of heat stroke is a core body temperature above 105 degrees. Other symptoms may include fainting, throbbing headache, dizziness, lack of sweating, red hot and dry skin, muscle weakness, rapid heart rate, rapid shallow breathing, behavioral changes, seizures, and unconsciousness. Unlike heat exhaustion, if you suspect someone is having a heatstroke the first move is to immediately call 911. After calling paramedics you can initiate first aid by moving the individual into an air conditioned environment, remove any unnecessary clothing, and take any action possible to cool down the body temperature. These actions may include a fan over the patient while wetting skin with water, apply ice packs to the patients armpits, groin, neck, and back, and immersing the patient in a shower or tub of cool water or ice.

UV Exposure

To begin lets first discuss what ultraviolet light / radiation is. "Ultraviolet" refers to the spectrum of light that is beyond violet. When we say that the light is beyond violet, we simply mean that is is of a higher frequency than violet light. UV radiation was fist discovered in 1801 by a German physicist Johann Wilhelm Ritter. He made this discovery while observing rays of invisible light beyond the violet end of the visible spectrum and noticed that these rays darkened silver chloride-soaked paper quicker than the violet rays themselves.

 In regards to the human impact that UV exposure has it can be both positive and negative. When most people think of UV exposure, they think of the harmful radiation emitted from the sun that causes sunburn and the potential for skin cancer. Over exposure to UV radiation significantly increases your risk factor for developing both melanoma and non-melanoma skin cancers. According to the EPA, each year there are more diagnosed cases of skin cancer than breast, prostate, lung, and colon combined. In fact, nearly one in five Americans will develop skin cancer at some point in their lifetime. Even scarier, nearly one American dies from skin cancer every hour. Melanoma (pictured below) is the most serious form of all the skin cancers and is now the most common form in young adults between the ages of 15-29.

In addition to skin cancer, overexposure to UV radiation can also lead to the formation of cataracts and other complications with the eyes. A cataract is the clouding of the lens in the eye that, if left untreated, could lead to blindness over time. Less common complications include pterygium, a form of tissue growth that can block vision, skin cancer around the eyes, and degeneration of the macula.

Now I did mention that exposure to UV light radiation can be both harmful and positive depending on your exposure. Although the risks associated with overexposure appear to be weigh in much more significantly than the positives, some exposure is beneficial. Small amounts of UV are beneficial in the production of Vitamin D. It can also be used to treat several diseases, including rickets, psoriasis, eczema, and jaundice. Of course this needs to take place under medical supervision, but as you can see, one needs to weigh the benefits of treatment vs the risks of exposure and consider the positive end of the spectrum.

Contact Dermatitis

In todays post I will be discussing the most common form of occupational skin disease, Contact Dermatitis. Contact dermatitis is a red, sometimes painful or itchy rash, that is caused by contact between your skin and a hazardous substance. It is often broken down into two separate categories. The first, irritant contact dermatitis is a non-immunologic reaction that develops as inflammation ofof the skin as a result of direct damage to the skin following exposure to a hazardous agent. The second, allergic contact dermatitis is an inflammation of the skin caused by an immunologic reaction triggered by dermal contact to a skin allergen. The big difference between the two is that allergic contact dermatitis is not confined to the site of contact and may result in systemic responses. While contact dermatitis is not life-threatening or even contagious for that matter, it is still very embarrassing and uncomfortable to the individual affected by it.

                                                                       Contact Dermatitis can be caused by a wide range of substances depending on an individuals skin sensitivity. Things such as soaps, cosmetics, plants, or fragrances can all trigger outbreaks. Those working in food service, cosmetology, healthcare, agriculture, cleaning, painting, construction, and mechanics are most likely to experience a harmful exposure. Poison ivy and poison oak are probably the most common causes for those who are not exposed to harmful substances in the workplace. Most people are sensitive to the plants oily sap which causes a blistering skin rash. Poison ivy can be hidden in your own back yard without you being aware if you don't know how to spot it.

Prevention and treatment of dermatitis greatly depends on whether or not the outbreak is acute or chronic in nature. Generally, to completely eliminate and prevent future outbreaks of contact dermatitis you need to identify the source of irritation and avoid exposure to this agent. Things such as rubber gloves can be worn to prevent harmful substances coming in contact with your hands. To treat acute dermatitis things such as wet dressings can be applied to the spot of irritation and steroids and antihistamines can help control the reaction. For chronic dermatitis your only options are really emollients and topical steroids aside from seriously avoiding exposure to harmful agents.

 

What many people do not know is that nearly 13 million workers are potentially exposed to chemicals that can be absorbed through the skin. Aside from contact dermatitis, dermal exposures can result in a variety of occupational skin diseases and disorders. It is important to spread awareness in the workplace so as to prevent individuals from experiencing this painful and embarrassing disease.

Asbestos

While my last few posts have mostly discussed dose-response and exposures in general, I would like to further discuss the very real consequences that can occur when an individual is exposed to one of these harmful substances. Now a days asbestos has gained a lot of awareness, in fact there is even an entire website dedicated to Asbestos with all kinds of information on it.  Be it an advertisement or commercial, everyone has seen the lawyer ranting about asbestos and mesothelioma but many do not know exactly what these actually are.

Asbestos was originally a praised discovery when it was recognized for its fire and heat resistance. It was used in everything from fire-proof vests to home and commercial construction. In most cases it was put into insulation but was also woven into fabrics and sprayed onto steel to protect the structural framework of a building in case of a fire. There are six types of asbestos minerals and they are chrysotile, amosite, crocidolite, tremolite, anthophyllite, and actinolite. Although different in their chemical compositions, all six forms of asbestos are carcinogenic. A picture of the fibers under microscope is provided below.

So what are the health hazards of exposure to asbestos? When materials containing asbestos are disturbed, tiny fibers are dispersed into the air. Once air born these particles can be breathed in and become trapped in the lungs for a long period of time. These fibers can accumulate and cause scarring and inflammation affecting breathing. The two most dangerous outcomes from exposure to asbestos are asbestosis and mesothelioma. Mesothelioma is a rare form of cancer that can only be caused by exposure to asbestos. Asbestos fibers lodge in the mesothelial tissue and cause cancer in the lining of the lungs. It can also form around the lining of the abdomen or heart. Mesothelioma is a very aggressive cancer and the problem is it can take anywhere from 20 to 50 years after the exposure before symptoms appear. Almost 3,000 cases of mesothelioma are diagnosed annually so it is easy to see why we needed to raise awareness and create some regulations. Hopefully overtime we will see a significant drop in this number now that we have cut out the use of asbestos in our buildings.

Time Weighted Average

Permissible Exposure Limits (PEL's) are actual legal limits determined by OSHA that limit the amount or concentration of exposure to certain chemical substances or physical agents (i.e noise) to employees while working. American Conference of Governmental Industrial Hygienists (ACGIH) as many of the permissible exposure limits that were set into place by OSHA were the actual threshold limit values established by ACGIH.

As mentioned in my previous post, most of the chemical exposures are expressed in parts per million. While OSHA is behind the actual adoption of these regulations I think it is important to give credit to the

Now as I also mentioned in previous posts, there are several ways exposure can be expressed. Be it Short Term Exposure Limits, Ceiling Limits, or what I plan to further discuss, Time-Weighted Averages. A Time-Weighted Average (TWA) is basically the average exposure to any hazardous material that an employee could expect to receive under standard working conditions and considering an 8 hour work day or 40 hours per week work week. Time weighted average allows for peaks and valleys to generate a single average concentration.

The average exposure is compared overtime to the occupational exposure limit to check for excursions. Excursions in exposure levels may exceed 3 times the TWA for no  more than a total of 30 minutes during a workday, and for no reason should they ever exceed 5 times the TWA, considering that the TWA is not exceeded. Basically if put simply, a worker can be exposed to higher concentrations so long as it does not exceed a ceiling, the exposure is not occurring for a long period of time, and the number of times that the worker is exposed to that dose of the hazard is kept to a bare minimum.

To calculate the TWA you multiply the concentration (C) by time (T) and then divide by this time.

The goal of having these permissible exposure limits and observing the time weighted averages is to limit the potential for adverse health effects while working on the job. Just to get a glimpse on how these limits are really protecting workers you can look as OSHA's ruling that limits exposure to respirable crystalline silica. OSHA estimates that the rule will save over 600 lives and prevent more than 900 new cases of silicosis each year, and that's by limiting exposure to merely one substance. 

Occupational Exposure Limits

In my last post I discussed Dose-Response and how exposure to certain substances (be it chemical, drug, or general toxic waste), can cause an effect on the exposed individual. In the past several decades we began to realize that many individuals have been exposed to certain chemicals in the workplace and that a number of these exposures have led to very serious and negative implications on the individual’s health. One such example involves asbestos and the development of a deadly form of cancer known as Mesothelioma in those individuals who were exposed to this material. This is merely one of many different examples and it was at this time that government knew it was time to take action. This led to the development of several standards geared towards protecting future generations of working class men and women.

When referring to chemical or other hazardous substances, performance standards for exposure limits are better known as Occupational Exposure Limits or OEL's. There are several types of OEL's, the most typical being the Time Weighted Average. This allows for ups and downs but considers the single average concentration and number of excursions that take place during worker exposure. Other OEL's include Ceiling or Short Term Exposure Limits (STEL) and standards for Vibration, Sound, Heat/Cold, Radiation, Strain, and Biological Exposure Indices. By definition, "An occupational exposure limit is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material of class of materials." 

The two biggest organizations created and tasked with developing these standards are the Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH). The American Conference of Governmental Industrial Hygienists are known for publishing their Threshold Limit Values or TLV's while the Occupational Safety and Health Administration refers to their limits as permissible exposure limits or PEL's. For more information on TLV's you can visit here. According to OSHA's website, 4,679 workers died on the job in 2014. As previously stated, all of these limits, standards, and guidlines are created with the intention of reducing this number of accidents and deaths in the workplace.

For both TLV's and PEL's exposure is generally expressed as parts per million (ppm) for gases and vapors and milligrams per cubic meter (mg/m3) for solids. When considering the OEL you are observing airborne concentration that workers may be exposed to and you want to know how long they can be exposed to this without adverse effects considering 8 hour shifts 5 days per week.

Dose-Response

When discussing dose response and its effect on human life, I think it is important to first understand the concept of the dose-response relationship. The dose-response relationship basically explains how the toxicity of a substance is not only dependent on that of its toxic properties, but also on the amount of time and dose that one is exposed to this substance. The medical definition of Dose-Response can be found here on Merriam Webster. It is common sense if you really think about it, the longer you are exposed to a toxic substance the more harm it will do to your body regardless of the concentration.

One note to add while discussing concepts, is the term known as the threshold dose. This is the dose or exposure level, below which he adverse effects of a substance are not expressed by the exposed population. When we refer to exposure, we are referring to the actual amount of the substance that will be absorbed into the body when exposed and not just the amount of the substance that is in the surrounding environment. Dose in some ways also takes into account the mass of the individual being exposed. Although it may seem that I am discussing dose-response in a negative light there are also many positives that come from studying this concept. Response to a substance may lead to the curing of a disease or simply relieving pain but in order for these to take place, the exposure levels must fall within the range of certain upper and lower bounds regarding the dosage. An example of a dose response curve is provided below.

The problem with illustrating the threshold dose is that a dose-response curve is not always a linear relationship. In fact, in most cases the relationship is a complex logarithmic or hyperbolic curve. One example of a Dose-Response Curve can be found here. On the other hand, the nice thing about dose-response curves is that they can contrast two or more different substances with varying toxicities. From here comparisons of the graphs can be useful when evaluating toxicity. In general, the greater the slope of the graph, the more toxic the material is. For a little further explanation on how the graph is plotted and what it contains you can click here.