Environmental Health and Public Health Risk Assessment - Term Paper Example

PUBLIC HEALTH RISK ASSESSMENT {Insert university name} {Insert instructor’s name} {Insert student’s name} September 18, 2012 ABSTRACT For the past decade, the public has become aware of harmful chemicals that are present in the environment. A high percentage of people have expressed concerns about chemicals and their health hazards. When the public are informed about toxic threats that impact on their health, they stop using the chemicals. Health risk assessment is a scientifically designed tool that assists in answering the aforementioned questions. Government agencies depend on health risk assessment to assist them in determining potential hazards that are of great significance. Health risk assessment can also be helpful in guiding regulators in preventing environmental hazards. On the other the public are in a position to learn the basics of health risk assessment and hence they can be in a position to understand both perceived and real environmental hazards of sulphur dioxide and toxaphene. Table of Contents ABSTRACT 2 Table of Contents 3 PUBLIC HEALTH RISK ASSESSMENT 5 INTRODUCTION 5 BODY 5 TOXAPHENE (CANCER) 5 Issue identification 5 Hazard identification 6 Dose-Response Assessment 6 Exposure Assessment 7 Risk characterization 8 Monitoring, review and consultation 9 Communication and consultation 9 SULPHUR DIOXIDE (NON-CANCER) 9 Issue identification 9 Hazard identification 10 Dose-Response Assessment 10 Exposure Assessment 10 Risk Characterization 12 Monitoring, Review and Consultation 12 STRENGTHS OR LIMITATIONS IDENTIFIED 12 TOXAPHENE 12 Strengths 12 Limitations 13 SULPHUR 13 Strengths 13 Limitation 14 CONCLUSION 14 REFERENCES 15 PUBLIC HEALTH RISK ASSESSMENT INTRODUCTION Chemicals can be either harmful or beneficial to human beings and animals depending on various factors like time and amount of exposure. Low levels of certain chemicals may good for human and animal health while high level may turn to be harmful. Health risk assessments are used to determine if certain chemicals are harmful to human health. The essay will involve a comparative study of both cancer and non-cancer risk assessment of toxaphene and sulphur dioxide. The study will further compare as well as contrast the approaches that are used and compare the same to the approach that is applied in each study with the Australian Framework for Environment Health Risk Assessment. The essay will follow the follow steps: issue identification, hazard identification, does-response treatment, exposure assessment, risk characterisation, monitoring review and evaluation and finally communication and consultation. BODY TOXAPHENE (CANCER) Issue identification The article discusses what toxaphene is by defining it as a complex mixture of polychroninated monoterpenes that has a wide pesticidal spectrum activity (ATSDR, 1995). Prior to its ban in 1982, it was used as an insecticide not only in the United States of America but also other parts of the world. Toxapheme has also been used by fish poison with an aim of killing undesirable fish. In 1982, U.S environmental protection agency cancelled toxaphene registration because of its acute and chronic toxic to aquatic life as well as carcinogenic risk human beings. Hazard identification The article gives background information on epidemiological and toxicological information on toxaphene. Toxaphene is defined as a complex mixture of a number of chlorinated terpenes that are structurally related having an average empirical formula of C10H10Cl81). There are past studies undertaken to reveal the verbal absorption of Toxaphene among the human population. There have been reports of deaths and poisoning caused by the oral absorption of toxaphene. The aforementioned was also evident in rats, mice and even fish. Studies have further revealed that toxaphene can be ingested via drinking water. Consequently, due to dermal exposure, toxaphene level is high in cow’s milk. Therefore, it is evident that the absorption is possible in both animals and human beings. In an experiment using rats, it was evident that toxaphene that is stored in the fat which is one of the prime tissues of rats. Moreover, toxaphene as well as its metabolites has been further detected not only in spleen and bones but also in lung, testes, heart, brain and kidney of rats. Dose-Response Assessment The article indicates that it uses the Slope Factor with an aim of describing the dose-response of toxaphene. Slope Factor is used for the purpose of determining cancer risks which are associated with exposure to either potentially carcinogenic or carcinogenic substances. It is evident that risk assessment was conducted based on the carcinogenic effects of toxaphene. The mentioned was as a result of epidemiological study conducted to describe toxaphene effects and data used was mainly drawn from National Council of Investigation (NCI). The findings indicated that the slope Factor for the mice was high. The findings were used to calculate the carcinogenic risk prevalent in human beings and the toxaphene factor was reported to be at 1.1(mg/kg/d). In another study, a different Slope Factor is used. Nonetheless, human data on the aforementioned is lacking, there is an assumption that there is cancer similarity in animals and human beings an aspect that forms the basis for using animal data. Furthermore, it is evident that the derivation of the Slope Factor conforms to the regression model linearity assumption. However, for the purpose of conformity, confidentiality is maintained and the study is conducted on the basis that high Slope Factor is appropriate for best results. Exposure Assessment LADD – Lifetime Average Daily Dose For air inhalation the LADD calcualation is conducted as below: LADD (mg/kg/d) = C (mg/m3) * IR (m3/d) * BW (kg) C = Average concentration in the ambient air during the exposure period IR = Inhalation rates (23 m3/d adults) BW is the Body weight (this is aggregate body weight) Exposure period (70 kg male adult) In the article, LADD is not only calculated for water but also for soil and air as an element of exposure to toxaphene. For example, the calculated toxaphene LADD from fish, ambient air and surface water soil indicates that toxaphene can result into carcinogenic risks in human beings. Hence, it can be concluded that calculated LADD for water, air and soil are an estimate of human exposure to the insecticide. However, there is an aspect of ambiguity in the manner is which both the past and current data are used. The mentioned unreliability of the data is an indication that toxaphene is not highly used. Consequently, the sample data used in the study indicates low level of toxaphene use in relation to the data presented. Additionally, the study used assumes the rates of ingestion and inhalation of toxaphene. It is further evident that only the male body weight has been used. Finally, the LADE and LADD are assumed to be equal in the study (Selah, 1991). Risk characterization Human health risk is calculated by multiplying LADD and SF. i.e. RISK= hazard x exposure. In this particular section, the hazard i.e dose response assessment and hazard identification as well exposure assessment are not only summarized but also integrated into qualitative and quantitative risk expression (IARC, 1979). Additionally, toxaphene cancer risk estimates are calculated by using linear lower-dose cancer risk equation as illustrated below: Risk = LADD × SF LADD = Lifetime average daily dose (mg/kg/d) SF = slope factor (mg/kg/d)–1 However, the total cancer risk is calculated cancer risks sum for every exposure pathway as: Total Exposure Cancer Risk = Risk (exposure pathway1) + Risk (exposure pathway2) . Furthermore, the cancer risk exposure indicates that a person is likely to have a 7.4 in every 100, 000 cases to contract cancer. The LADD figures also indicate that a pesticide is a mixture with other chemicals (Reuben, 1979).The revealed figures can be different if Toxaphene is used alone. The pathways are exclusive of dermal absorption. The calculated figures are different for men, women and children. Monitoring, review and consultation The research shows that Toxaphene findings are basically on animal information. There is no accurate information on the extent of human exposure. The study focused on only rats and mice. The subsequent application of the chronic results is presumed erroneous (Wiley, Root & Peek, 1996). Communication and consultation The different approaches in the assessment of health risks also suffer from diverse pitfalls however, they are in line with Australian Framework for Environmental Health Risk Assessment. SULPHUR DIOXIDE (NON-CANCER) Issue identification The article discusses what sulphur by defining it as a toxic substance that has diverse health effects. According to Daniel (1995) the main route of cancer exposure is via inhalation and the respiratory system is the target organ. Sulphur dioxide is a chemical substance present in fuels. A fuel is a chemical substance that can burn. It is believed that is a non –cancer chemical substance (Wiley, Root, & Peek, 1996). This is clear from the quotient indicators used in this study. Nonetheless, the study did not provide concrete information and supportive arguments as in the case of the pesticide. Hazard identification The article gives background information on epidemiological and toxicological information on suphur. When sulphur is inhaled it is absorbed to the respiratory tract organs of human beings before it is distributed to all other body parts including the bone marrow and the brain. Studies have indicated that sulphur reaches the lower respiratory tract of human beings only after it has been absorbed into a particulate matter that is suspended. Sulphur has acute health effects which include: breath shortness, wheezing, bronchospasms and bronchitis. Dose-Response Assessment The article indicates that it uses an established REL to describe the dose response of sulphur dioxide. The Reference Exposure Level (REL) is the threshold for testing the adverse health effects relative to set control groups. The study indicates the concentration of suphur dioxide in the human system. The concentration is expressed as a linear function of the exposure time. However, it is challenging to determine the dose response in suphur dioxide case (Dab & Scott, 1999). Exposure Assessment The article illustrates exposure as the amount sulphur dioxide that gets into contact with human population. It indicates that it calculates an ADD for air for adults, children and infants. The study applied a scenario assessment approach were developed for not only acute (1 hr) but also for intermediate (24 hrs) and chronic (annual) exposure duration for hypothetical receptors in four age groups i.e infants (1 year), children (6 yrs), children (12 yrs) and adults (19-75 yrs). The calculation of ADD is identified below: ADD = (C × IR × ED)/(BW × AT) [1] Whereby ADD = average daily dose of the chemical (μg/kg·day) C = concentration of the chemical in the atmosphere (μg/m3) IR = inhalation rate (m3/day) ED = exposure duration (days) BW = average body weight of the receptor over the exposure period (kg) AT = averaging time (days). In calculating an acute exposure rate, the equation above is also used only that ADD is replaced by AHD (average hourly dose). Consequently, In order to estimate the worst case scenario, it is assumed that the vulnerable receptors use most of the period in the study area. There is also continuous exposure. Children are said to have long exposure in relative to adults (Matooane & Dab, 2001). This is attributed to playing habits. The indoor exposure to sulphur dioxide is approaching the zero value. This is a result of the use of electricity in most homes in the study area. The use of wood or coal is very negligible. The inhalation rate and figures for body groups for different age groups are used in the study. Risk Characterization The article indicates that it calculates risk by using a HQ = ADD / REL. Risk characterization involves integration of the first three steps. However, risk characterization entails hazard quotient calculation (HQ) which is HQ = ADD/REL or HQ = AHD/REL. The HQ calculated was considered to be considered as safety benchmark (Preston-Whyte & Diab, 1980). Local. HQ values < 1.0 is a clear indication that sulphur dioxide is not likely to result into adverse health impacts. However HQ values HQ values > 1.0 is an indication that suphur dioxide is likely to result into adverse health effects (Law, 1997). Monitoring, Review and Consultation The finding in the study indicates that exposure as a result of suphur dioxide pollution is sensitive to time exposure. Therefore, the existing assumption that indoor exposure to suphur dioxide is zero requires further investigation. STRENGTHS OR LIMITATIONS IDENTIFIED TOXAPHENE Strengths The approaches used provide a step to step analysis that is similar to steps in the Australian Framework for Environmental Health Risk Assessment. For instance the article provides a number of pathways possible for contacting the disease. Consequently, the Slope Factor is not only relevant but also elaborate in the manner which it is applied. In the representation of the assessment, the study uses different epidemiological information to attain its aims. Lastly, the steps used in report writing are in accordance with Australian Framework for Environmental Health Risk Assessment. Limitations Despite the strengths of the study, it has also some limitation in accordance with Australian Framework for Environmental Health Risk Assessment. It is evident that the study lacks a separate data on toxaphene impacts and its relation to cancer. Additionally, the existing assumption that risk exposure is continuous is erroneous as the study does not provide pathways that are conclusive in nature. Consequently toxaphene absorption via the dermis is not clear. Additionally, there is an assumption that ingestion and inhalation rate of toxaphene is the same. Another limitation is that high Slope Factor is preferred without putting into consideration other environmental factors and human beings have not been used in the study. The study has used animals in its experiments. However, even though human beings and animals have similar attributes, there have different structural and human behaviors. Recent studies on causes of cancer reveal that the disease is caused by poor lifestyles. SULPHUR Strengths The study of sulphur dioxide tends to provide a clear case for the environmental health risk assessment in accordance with Australian Framework for Environmental Health Risk Assessment. The correlation of the indicators is crucial in the understanding of their workability. Consequently, the study tends to point out that it is not always true to conform to the public opinion. There is a public belief that the use of sulphur dioxide is likely to cause cancer which is not true. Limitation The limitation of the study is that there are no other studies to compare with the it with an aim of verifying the findings. The application of the method cannot be recommended without varying the exposure patterns. Hence, it is important to determine the exposure patterns and indoor suphur dioxide pollution levels need to be investigated further as the current study has mere assumptions about the same. CONCLUSION Risk assessment is a scientific process that is used to determine the probability/chance that an adverse outcome can occur as a result of environmental exposure, especially in chemicals. These two chemicals need further research on their health risk incidences. For chemicals that cause cancer such as toxaphene, the general assumption is that there are no exposures that result into zero risk only if there is a clear evidence to support the same. However, from the above studies, it is evident that a number of factors may make it challenging to estimate the risk of cancer. This is due to the fact that cancer is a progressive disease as a result of its series cellular transformations that take place before cancer develops. The study results for sulphur dioxide show that the popular belief that there are high incidences of South Durban residents developing respiratory diseases is a fallacy. This is evident from the case studies discussed above. The presence of children indoors and outdoors has the similar impact due to the use of electricity in the study area. The models for health assessment are simple and reliable to use, particularly in the case of sulphur dioxide. Local variations should be considered in the study of exposure patterns. The findings are also clear that residents of South Durban have different exposure patterns. There is a need to investigate further the levels of indoor sulphur dioxide exposure. This is significant for conclusive results to be made. The cases above need to be expounded so as to enable national health agencies to formulate accurate and conclusive recommendations. REFERENCES Agency for Toxic Substances and Disease Registry (ATSDR) (1995) Toxicological profile for Toxaphene. Agency for Toxic Substances and Disease Registry, Atlanta Daniel, W.W (1995) Simple linear regression and correlation. In: Biostatistics: A foundation for analysis. Department of Environmental Affairs and Tourism. Plan to combat air pollution in South Durban announced [media statement]. Cape Town, South Africa: Ministry of Environmental Affairs and Tourism, 28 Nov 2000. Dab ,R.D & Scott D. (1999) Urban air pollution and quality of life: Case study of a community struggle in Durban, South Africa. 19th Annual Meeting of the International Association for Impact Assessment (IAIA), Glasgow, 1999 Jun 15–19. Fargo, ND: IAIA, 1999. International Agency for Research on Cancer (IARC) (1979) Toxaphene (polychlorinated camphene). In: ARC monographs on the evaluation of the carcinogenic risk of Chemicals to humans, 20,327–48. Law, E.A. (1997). Characterization of odour patterns in Durban [honors thesis]. Durban, South Africa: School of Life and Environmental Sciences, University of Natal. Matooane L, & Dab ,R.d (2001). Air pollution carrying capacity in the South Durban Industrial Basin. South Africa Journal of Science, 97, 450–53. Preston-Whyte, R.A, & Diab ,R.D., (1980). Local weather and air pollution: The case of Durban. Environment Conservation, 7,241–44. Reuben, M.D. (1979). Carcinogenicity of Toxaphene: A review. J Toxicology Environmental Health,5, 729–48. Selah, M.A. (1991). Toxaphene: Chemistry, biochemistry, toxicity and environmental fate. Rev Environment Contamination Toxicology,118, 1–85. Wiley, D., Root C., & Peek S. (1996). Report on the state of the environment and development in the Durban Metropolitan Area. Durban, South Africa: Physical Environment Service Unit, North Central Council, Durban Metropolitan Area vol 3 pp. Read More