Effects of Polychlorinated Biphenyl (PCB)

Effects of Polychlorinated Biphenyl (PCB) Polychlorinated Biphenyl (PCB) is a persistent organochlorine that has 209 congeners and can be divided into two categories, dioxin-like and non-dioxin-like. Although these two categories have different structures and toxicological profiles, both have an adverse impact on the human health [1]. Since PCB is a stable chemical and can withstand extreme temperature and pressure, it was heavily used back in 1929 for electrical equipment [2]. While the production of PCB was ceased in 1977, traces of PCB can still be observed on the Great Lakes for it was once used as a disposal site along with the possibility of accidental leaks. From lakes, it can move into different waterways and later be passed on by organisms. Long-range-transport of PCB vapours through air currents also functions as a dispersion mechanism in the ambient air [3] [4] [5]. Anyone can be susceptible depending on the rate of the exposure and the amount of stressor a person had been exposed to. PCB can enter the system thro ugh ingestion, inhalation and dermal contact, all of which can essentially bioaccumulate and inhibit the bodys natural processes in the event that the receptor had exceeded the threshold. PCB has been linked to endocrine dysfunction, reproduction deficiencies, chloracne, liver damage and kidney cancer [6]. Recognizing credible sources is a key factor in toxicity assessment. This allows the reader to acquire more information about the chemical of concern and make an informed decision. Some credible sources are listed below: Agency for Toxic Substances and Disease Registry European Chemicals Agency Health Canada United States Environmental Protection Agency World Health Organization     Ã‚   3.1. What happens when PCB enters the body? Humans absorb PCB through inhalation, ingestion and dermal contact. On bioassays conducted, it was observed that animals absorbed PCB well when administered orally and less absorbed when exposed through dermal contact. While inhalation is an accounted pathway for PCB, there is inadequate data to identify the absorption rates. Upon absorption, PCB is dispersed into the lipophilic cell membranes in the gastrointestinal tract. It then circulates into the blood vessels and enters the lymphatic system. Due to the lipophilic nature of PCB molecules, it is readily absorbed by the fatty tissue. In autopsies conducted, the liver, adipose tissue, brain and skin usually contains higher concentrations of PCB. Elimination of PCB can be through excretion of feces, urine and breast milk [7]. When exposed to PCB, symptoms include severe acne, swelling of the upper eyelids, discolouring of the nails and skin, numbness in arms and/or legs, weakness, muscle spasms, chronic bronchitis, and neurological complications [6]. 3.2. Acute and Chronic Effects PCB exhibits both acute and chronic effects. Although it demonstrates low potential in producing acute effects, however, due to the risk it poses in human health in the long-term, it is still deemed to be a public health concern. Skin lesions particularly chloracne has been observed during occupational exposures. Nausea and headaches were also reported yet this could be primarily due to the solvents in the PCB mixtures. Subsequently, long-term exposure to PCB has been linked to reproductive deficiencies, liver damage and kidney cancer [8]. 3.3. Threshold vs Non-threshold PCB has shown evident carcinogenicity in animals and therefore is considered to be non-threshold substance by USEPA. The data for human carcinogenicity for PCB mixture is deemed to be inadequate but suggestive. Essentially, PCB can also be classified as threshold substance because of its non-cancer potential in lower concentrations and short-term exposure [9].   3.4. What effects does it have? Carcinogenic US EPA labeled PCB as Group B2, a probable human carcinogen. This was based on the experiment of exposure of rats to several mixtures of PCB that are often found in the environment [10]. On a study published in 1976, occupational exposure to PCB increased the mortality from cancer. However, the outcomes were mixed since the study only found limited deaths and incomplete exposure assessments [7]. Mutagenicity There were insufficient data involving the mutagenicity of PCB [7]. A bacterial test which distinguishes chemical mutation effects was conducted on PCB. Although PCB demonstrated negative results, this was not uncommon since PCB has complex compounds and pathways [11]. Reproductive Toxicity Oral administration of PCB on animals has displayed toxicity effects but dermal and inhalation exposure were not available. Exposure of rats and mice to high doses of PCB had produced several effects. The effects documented were decreased conception rate, pro-longed menstruation, decreased litter size and reduced sperm count. Rats and mice that were exposed to PCB while lactation suggested long-lasting adverse effect on the offspring. On another study, PCB is also associated to estrogen-related effects [7]. 4.1. Bioassay Overview The slope factor of PCB was based upon the studies conducted by Brunner et al. (1996) and Norback and Weltman (1985). A group of male and female Sprague-Dawley rats were exposed to different Aroclor. Groups of 50 female or male rats were orally administered with 25, 50 or 100 ppm Aroclor 1260 or 1254; 50 or 100 ppm Arcolor 1242; or 50, 100, or 200 ppm Aroclor 1016. At 104 weeks, the rats were killed. Liver adenomas or carcinomas were discovered in all female rats for all Aroclors and male rats for Aroclor 1260. While thyroid gland follicular cell carcinoma was evident on male rats, female rats also exhibited mammary tumors at a later age. On another study, male and female Sprague-Dawley rats were exposed to 0 or 100ppm of Aroclor 1260 for 16 months and subsequently reduced to 50 ppm for another 8 months. Tests were executed in different months to understand the changes in the structure of the rats. The intensity of the damage on the liver increases as you progress through the months. On the 29th month, most of the female rats displayed carcinoma and neoplastic nodules whereas male rats had lesser incidence [10] . 4.2. Published Benchmark A tiered approach was used by USEPA to determine the cancer potency of PCB. Upper-bounds provide precision while central-estimates are appropriate for estimating risks. Potency values are dependent on the exposure pathway. For exposure pathways with increased risks, we use High Risk and Persistence. Exposure pathways that decrease risk are appropriate on Low Risk and Persistence. Lowest Risk and Persistence is developed from Aroclor 2016, therefore it is appropriate for congeners with more than for chlorine. The slope factor can be generated by dividing 0.10 by ED10 (Estimated dose associated with 10% increased incidence, in mg/kg-d) [12]. High Risk and Persistence Low Risk and Persistence Lowest Risk and Persistence Upper-Bound Slope Factor 2.0 per (mg/kg)/day 0.4 per (mg/kg)/day 0.07 per (mg/kg)/day Central-Estimate Slope Factor 1.0 per (mg/kg)/day 0.3 per (mg/kg)/day 0.04 per (mg/kg)/day Criteria for use Food chain exposure Sediment or soil ingestion Dust or aerosol inhalation Dermal exposure, if an absorption factor has been applied Presence of dioxin-like, tumor-promoting, or persistent congeners Early-life exposure (all pathways and mixtures) Ingestion of water-soluble congeners Inhalation of evaporated congeners Dermal exposure, if no absorption factor has been applied Congener or isomer analyses verify that congeners with more than 4 chlorines comprise less than 1/2% of total PCBs. Figure 1 Tiers of Human Slope Factors For Environmental PCB [13]. Uncertainty Factors It is important to know that not everyone responds equally to a given chemical. Populations with higher sensitivity may be associated with increased risks. Also, the genetics and lifestyle of a person must be accounted as this pose potential change on the dose-response trend. Furthermore, it is essential to recognize that the mixtures of PCB tested in animals are Aroclor mixtures which have been pre-determined and not environmental mixtures that had bioaccumulated which are generally more potent [10]. Figure 1 shows that the slope factor is dependent upon the exposure pathway. Although these are just estimates, scientists have dedicated their time to conduct bioassays where we can extrapolate the data to potentially understand the dose that can harm humans. However, it is also crucial to know that environmental processes can alter the PCB concentrations, therefore it is best to be educated on how you can be exposed to PCB and how you can avoid this. To improve the assessment, studies concerning sensitive population should be further considered and assessed. Since PCB concentrations are altered in the environment, animals or humans that are already exposed could be used to investigate and compare the differences with the experiments done in the laboratory. In addition, it was not mentioned why rats were chosen as experiment parameters, analyzing parameters used could help readers discern why rats are relevant for the study. [1] P. Heikkinen, . L. T. M. van der Ven,, F. Rendel, R. Roos, J. Esteban, M. Korkalainen, S. Lensu, H. Miettinen, K. Savolainen, S. Sankari, H. Lilienthal, A. Adamsson, J. Toppari, M. Herlin, M. Finnila, J. Tukkanen, H. Leslie, T. Hammmers and G. Hamscher, Toxicological Profile of Ultrapure 2,2à ¢Ã¢â€š ¬Ã‚ ²,3,4,4à ¢Ã¢â€š ¬Ã‚ ²,5,5à ¢Ã¢â€š ¬Ã‚ ²-Heptachlorbiphenyl (PCB 180) in Adult Rats., PLoS ONE, vol. 9, no. 8, pp. 1-26, 2014. [2] PCBs: Polychlorinated Biphenyls, [Online]. Available: http://www.greenfacts.org/en/pcbs. [Accessed 2 February 2017]. [3] S. Fields, Great Lakes Resources at Risk, Environmental Health Perspectives, vol. 113, no. 3, pp. 164-173, 2005. [4] PCBs in Great Lakes Sediments, [Online]. Available: http://www.greatlakesmapping.org/great_lake_stressors/1/pcbs-great-lakes-sediments. [Accessed 1 February 2017]. [5] Polychlorinated Biphenyls (PCBs) Toxicity, 14 May 2014. [Online]. Available: https://www.atsdr.cdc.gov/csem/pcb/docs/pcb.pdf. [Accessed 02 February 2017]. [6] H. Canada, Health Canada, [Online]. Available: http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/environ/pcb-bpc-eng.php#ba. [Accessed 20 February 2017]. [7] M. L. S. K. M. C. S. D. C. T. D. R. Dr Obaid M. Faroon, World Health Organization, 2003. [Online]. Available: http://www.who.int/ipcs/publications/cicad/en/cicad55.pdf. [Accessed 13 February 2017]. [8] G. Letz, The Toxicology of PCBs-An Overview for Clinicians, West Journal of Medicine, pp. 536-538, 1983. [9] United States Environmental Protection Agency, [Online]. Available: https://www3.epa.gov/region02/superfund/hudson/hhra-app-c.pdf. [Accessed 20 February 2017]. [10] United States Environmental Protection Agency, 1 October 1996. [Online]. Available: https://cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=294. [Accessed 21 February 2017]. [11] Polychlorinated Biphenyls and Polybrominated Biphenyls., in IARC Monographs, IARC, 2016. [12] U. S. E. P. Agency, PCBs: Cancer Dose-Response Assessment and Application to Environmental Mixtures, September 1996. [Online]. Available: https://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=12486. [Accessed 21 February 2017]. [13] United States Environmental Protection Agency, 1 June 1994. [Online]. Available: https://cfpub.epa.gov/ncea/iris2/chemicalLanding.cfm?substance_nmbr=294. [Accessed 21 February 2017].

Five Year Business Plan Essay -- essays research papers

SMC Company Five-Year HR Forecast The local labor market has continued to shrink and labor costs have continued to soar over the past two years. SMC's workforce has now become bilingual and has had to deal with occasional unsuccessful attempts for its labor force to organize a union. To remain competitive for the next five years and sustain its growing sales, SMC Company will have to address staffing, employee development and training, compensation and benefits, employee relations, and safety and health issues. SMC must consider elements in developing the five-year plan such as technological advances, globalization, diversity, e-business and ethics. The ultimate goal at SMC Corporation is continued growth. One aspect that will determine SMC’s success is to predict what labor will look like over the next five years. By looking at the demographics of the Shaker Heights labor force along with the available work force of the surrounding area, a forecast of potential employees can be produced. SMC must look for new inventive ways for the current staff to increase productivity. These actions give SMC the ability to empower their employees to think on their own and present ideas that increase productivity without increasing headcount. SMC can also look to The Bureau of Labor Statistics of the U.S. Department of Labor for information on the projected supply and demand for any specific occupation. (Dessler, 2000, pg. 133). When considering the projected labor force, SMC must predict future cost of labor. SMC has been located in Shaker Heights since it’s inception. One concern for the future is being able to maintain all operations of the company in this location. An aspect that may effect keeping the entire production in Shaker Heights, is the cost of the local labor force versus cost of labor elsewhere and the global manufacturing environment. For instance the cost of labor (US dollars) in Mexico averages $1.51 per hour to the United States who averages $17.20 per hour, to the United Kingdom who averages $13.77 per hour. (Dessler, 2000, pg. 617). With such a broad range in labor costs SMC should consider building a manufacturing facility outside the US. SMC will need to find ways to increase production without dramatically increasing overhead. With all the departments working together, SMC will continue to meet their goals while constantly upgrading their processe... ...mployees are empowered to do their jobs and feel they are part of the company. * Technological advances - Create employee learning resource center * Globalization - Track international marketing trends and employee compensation packages to attract and retain international workforce(differences in cultures and customs in Mexico and England need to be evaluated) * Diversity - Conduct seminars on diversity within the workplace * E-Business - No immediate changes * Ethics – Create a volunteer board to help employees become active in the community Safety and Health measures will be implemented to ensure a safe work environment. * Technological advances – Time and motion studies * Globalization - Preview health issues in Mexico,England and the U.S. which may affect employees * Diversity - Make sure that all safety and health posters are printed in both languages * E-Business – No plans at this time for any e-business applications as pertains to health and safety * Ethics - Do environmental survey to ensure that the production plant emissions are not harming the surrounding area. Add links on company intranet to organizations such as OSHA, ISO and EPA.   Ã‚  Ã‚  Ã‚  Ã‚  

My words of Wisdom

My Words of Wisdom We are all human beings who need to live together on the same earth, but different environments have different characteristics that can help us achieve goals. Some of us like to stay in the safe zone and enjoy the tranquil moments; some of us like to conquer the Nonverbal of our imagination and enjoy exciting moments; some of us with creative spirits enjoy taking extraordinary journeys. No matter which type of life we choose or which type characteristics we have, challenge always acts as a naughty kid, who hides in he corner and makes us either scream and run away or smile and embrace him as a friend.Lee Perry said, â€Å"You can do what you think you can do, so think you can do it, and do it. † The image math gave to me is a weirdo model consisting of a digital compiled body covered by parabola hair send out flashing radical signals once in a while. The model's circular face is embedded with lonely points for eyes and a logical expression that IS dry and wi thout tedious emotions. When we draw close to it, we feel like we are lost in a barren dessert. There we step into a sea of sand, dazed by the mirages of different types of questions which make us flounder hopelessly to find our direction.Although our survival desire is strong, we are too often too lethargic to stand up and confront our delusions of grandeur. Every time when I attended math class, I was scared to step into the classroom. Why? Not all Asians are geniuses at math; at least I am the one who is not. The math terminology spoken out from the math teacher was an alien language that blew through my ears and left a breeze in my brain but no knowledge manned. The problem or test I got from the math class was like a blank puzzle, but had no idea how to solve it.I finally find the way to solve this problem. I realized that there was no way that I could solve this problem or test; so I quit. Coming to the U. S. Gave me a second chance to retake the math, and I appreciate this ch ance. With a speeding heartbeat, I walked into my first math class (MAT 120) at MAC. In my mind, felt a bunch of questions swirling like a whirlwind around in my brain. I imagined that I heard a devil's choice shouting out with a contemptuous laugh, â€Å"You think you will understand the math in English?There's no way! † In my deepest mind, a voice burst out like a volcano, and the energy flowed into every cell of my body: â€Å"In the future, do not look back and view your life with regret; do the best you can now so that you can look forward to a promising future. † â€Å"Challenge accepted! † I told myself. Every class when I listen to the lesson, my ears start to translate the instructor's words, and save information into my memory area. I do not skip the difficult problems.I read the book to understand the examples, ask friends, teachers, and tutors questions about what I do not fully understand to help me boost my knowledge. Spend whole afternoons working with tutors and studying in the math center to finish my homework. Gradually, the way American instructors teach me becomes like a sparkling rope that guides me in the right direction as take the long, dark journey to conquer math. The method that tutors taught me like a sword of wisdom to help me eliminate the math enemies. I realize that I enjoy the moment when my pen writes out the right answers to problems.I enjoy seeing those numbers dance with cheerful rhythm to celebrate their lively show in the realistic world. In that moment, I know that I have learned how to treat math as a part of my life, not a weirdo model that I am scared to touch. When I received the highest score after finishing my first math class at MAC, I was crying and laughing. The complex emotions I felt were like a salad mixed with different ingredients, full of sweet, sour, spicy, and bitter tastes. Challenges are monsters if people are too scared to confront them and convert them onto allies.Challenges are only fortunate if people embrace them as they are, accept the responsibility to grow to deserve them, and dedicate themselves to making them a vibrant part of their lives. Then, in old age, people can look back upon their lives and see how the path that they have taken has led them upward to a mountain top. From this summit, they can view the distant valleys and say to themselves, â€Å"l have followed a good path, have kept the Way, and I have achieved my goals. I have lived a good life. Now, look forward to my next challenge. †

I Am A Little Bit Crazy - 1428 Words

Hello! I would first like to mention that this letter will be a little bit crazy, all over the place, and probable a total mess because I’m horrible at writing letters. Well, formal letters. In other words, good luck reading this. This paragraph is going to be a lot of mushy feels and appreciation and afterward I will introduce myself. I just wanted to thank you for inspiring me to follow my dreams, wherever they shall lead me. You’ve made me realize that I would rather spend my life working my butt off pursuing careers’ that may not make a lot financially, but will make me happy. To pursue photography, no matter how challenging or down I feel about my photographs, to keep practicing, pushing and learning after my failures, since those are the only ways to improve. To (even if nothing I write even gets published or noticed), keep writing the stories that have been created in my head, no matter how different or risky they may seem. Even if I may love them while also thinking they’re a little crazy and no one will ever like them. I’ve learned from you that the worst I could do is not write them. To not create a story. You’ve inspired me to instead of going through with an e ducation then becoming a lawyer just for making a lot of money and be able to enjoy luxuries I may enjoy, to pursue an education in business and marketing, (also photography and writing) because I love watching companies, nonprofits, stores and business grow. I love promoting people and their thing,Show MoreRelatedAnalysis Of Lee s The Great Gatsby By F. Scott Fitzgerald991 Words   |  4 Pagesturned my world upside down. Daphne Lee was born on February 5th, 1997. She lived in Colorado with her parents and little brother. From the outside, she seems completely ordinary, but not so much on the inside. She does not have any problems mentally or physically, though I am surprised she does not. She has changed my perspective on everything. 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