ENSC 201 Lecture Notes - Lecture 8: Lead, Bioavailability, Methylmercury

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orangecat922

13 Apr 2017

School

Queen's University

Department

Environmental Studies

Course

ENSC 201

Professor

Louise M Winn

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Document Summary

Metals such as zinc (zn), cadmium (cd), mercury (hg), lead (pb), etc. The term heavy metals is vague, often misused and should be avoided - don"t use it. Millions of people exposed to toxic levels of arsenic in drinking water - from a natural source. Some metals or inorganic elements may be essential for good health, some are toxic above certain concentrations and some are both. Zinc: essential at low concentrations, but generally non-toxic for humans. Lead: considered toxic to humans, possibly even at very low concentrations. Selenium, fluorine: essential at low concentrations, toxic at high concentrations. Natural concentrations of metals and regulations: zinc as an example. Canadian soil quality guideline 200 mg/kg (based on toxicity data) Soil developed over the rocks may also be high in metals, plants may uptake metals (pathways of exposure) Humans are more tolerant of zinc than fish. Mining involves crushing rocks and exposing them to oxygen and water.

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Toys for children are made in numerous countries and then exported to buyers throughout the world. In some countries, such as the United States, certain protection exists to make sure that toys are safe for children. The U.S. Consumer Product Safety Commission (CPSC) regularly issues recalls of toys that have the potential to expose children to danger such as lead or other heavy metals. For example, lead may be found in the paint used on toys and in the plastic used to make the toys. If ingested (e.g., children chewing on toys), lead is poisonous and can damage the nervous system and cause brain disorders. Lead is also a neurotoxin that can accumulate in both soft tissue and bones in the body. For these reasons, lead was banned in house paint, on toys marketed to children, and in dishes or cookware in the United States in 1978. Also, in an agreement between China's General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) and CPSC, the Chinese agreed to take immediate action in 2007 to eliminate the use of lead paint on Chinese manufactured toys that are exported to the United States. With China's prominence as a toy manufacturing country, this agreement was a step toward making safe products for children. Still, lead continues to be a hazard in a quarter of all U.S. homes with children under age six. In fact, a wide range of toys and children's products, including many market-leading and reputable brands, often contain either lead or other heavy metals (e.g., arsenic, cadmium, mercury, antimony, or chromium). Estimates exist that suggest that one-third of Chinese toys contain heavy metals. This is a major problem given that China manufactures 80 percent of the toys sold in the United States. Researchers from Greenpeace and IPEN conducted a study by buying 500 toys and children's products in five Chinese cities. They tested the products with handheld X-ray scanners and found that 163 of the toys were tainted with heavy metals above the norm (32.6 percent). These contaminated toys not only poison children when chewed or touched but can enter the body through the air they breathe, said Ada Kong Cheuk-san at Greenpeace. While lead in the paint on toys has not been eliminated, the focus on cleaning up a lead in the paint has been given front-page coverage ever since the agreement to eliminate it in 2007. It is certainly not gone, but at least more and more people are paying attention. Several organizations both governmental and privates are examining lead-based paint in toys continually. For example, the New York Times and Consumer Reports recently found that dangerous products for children are still widely available. The Ecology Center has created a website called HealthyStuff.org that contains a database of toys and other products that have been tested for dangerous chemicals. While lead in paint seems to be in focus, the use of lead in plastics has not been banned! Lead is used to soften the plastic and make it more flexible to allow it to go back to its original shape after children play with the toys. Plus, lead may also be used in plastic toys to stabilize molecules from heat. Unfortunately, when the plastic is exposed to sunlight, air, and detergents, for example, the chemical bond between the lead and plastics breaks down and forms dust that can enter the human body. Another unfortunate part about lead is that it is invisible to the naked eye and has no detectable smell. This means that children may be exposed to lead from toys (and other consumer products) through normal playing activity (e.g., hand-to-mouth activity). As everyone with children knows, children often put toys, fingers, and other objects in their mouths, exposing themselves to lead paint or dust. Children are also more vulnerable to lead than adults; there is no safe level of lead for children. The worldwide toy industry has published a voluntary standard of 90 parts per million for lead in toys, which, of course, is greater than a ban on lead in paint used for toys and in the materials used to make the toys (such as plastics). But since 2007, the world has at least seen stricter standards either voluntary or regulated standards that make it safer for children to play with newly purchased toys. The CPSC in the United States, the European Union, and China's AQSIQ is actively monitoring and seemingly enforcing stricter standards. But, according to Scott Wolfson of the CPSC, many toy manufacturers have been violating safety regulations for almost 30 years. So, are toys safer now than they were before 2007, and are they really safe to play with throughout the world? What do we do with old toys? Sources: M. Moore, One-Third of Chinese Toys Contain Heavy Metals, The Telegraph, December 8, 2011; P. Kavilanz, China to Eliminate Lead Paint in Toy Exports, CNN Money, September 11, 2007; U.S. Centers for Disease Control and Prevention. www.cdc.gov; the U.S. Prosecutes Importers of Toys Containing Lead, Phthalates, American, February 26, 2014.

CASE DISCUSSION QUESTIONS 1. How realistic do you think it is to create a world standard for toys concerning their safety and use by children? 2. Should we ban products from a country that does not follow standards similar to what the U.S. Consumer Product Safety Commission suggests for the United States? Is the CPSC overprotective? Should each country have its own guidelines? Why or why not? 3. If there are health risks associated with lead poisoning, what about related areas such as lead in drinking water (e.g., the issue that came to the forefront in the 2016 U.S. presidential campaign regarding water supply in Flint, Michigan)? 4. Is lead in toys a financial, or cost, issue? Why have we not seen the toy industry monitor and do something about the lead problem, even though we have known about it for more than 30 years?

periwinklehornet842

Can anyone help me with the following questions, it is due tonight and im having a hard time figuring most of these out and in-between a couple of answers. Thanks!

1. Which of the following is the PRIMARY goal of risk assessment?

A. maximize profit

B. balance risks and benefits

C. reduce liability

D. determine lethal doses

2. The probability of an adverse outcome based on the exposure and potency of a hazardous agent is known as the:

A. toxicity

B. risk

C. hazard

D. margin of safety

E. therapeutic index

3. Risk Assessment includes all the following, except:

A. risk characterization

B. exposure assessment

C. dose-response assessment

D. hazard identification

E. cost-benefit analysis

4. The process of making risk information understood by local officials, community groups and other stakeholders is known as:

A. risk management

B. risk characterization

C. risk communication

D. risk perception

E. risk estimation

5. The Hazard Identification step in the risk assessment paradigm may include which of the following:

A. in vitro testing

B. structure-activity relationships

C. animal bioassays

D. epidemiologic data

E. all of the above

6. A basic premise of carcinogen risk assessment is that:

A. surface area is proportional to body weight

B. chemicals that cause tumors in animals will cause tumors in humans

C. all dosing regimens are equivalent

D. all animal strains are relevant

7. The Point of Departure (POD) for a low-dose extrapolation could be which of the following:

A. NOAEL

B. LOAEL

C. BMDL

D. none of the above

E. all of the above

8. The benchmark dose (BMD) approach is preferred over the NOAEL/LOAEL approach for all the following reasons, except:

A. the full dose-response curve is considered

B. it includes a measure of variability

C. the same benchmark response be used across studies

D. it results in lower reference values

9. A biochemical change, functional impairment, or pathologic lesion affecting an organismâs performance, and reducing its ability to respond to environmental challenges is known in risk assessment as the

A. point of departure

B. benchmark dose

C. adverse effect

D. carcinogenic effect

10. When there is a cancer risk of 1 in 10,000, this is considered to be of

A. high concern

B. moderate concern

C. somewhat low concern

D. no concern at all

11. Which toxicant is commonly found in indoor air due to off-gassing of plywood and furniture?

A. arsenic

B. lead

C. methylene chloride

D. dioxin

E. formaldehyde

12. Which if the following was NOT an event in the United States that triggered widespread awareness of environmental issues in the 1960s?

A. Relocation of families from Love Canal in Niagara Falls, NY

B. Cuyahoga River catching on fire in Ohio

C. Publication of Silent Spring by Rachel Carson

D. Nationwide federal ban of smoking cigarettes in bars and restaurants

13. The study of the fate and effects of chemicals in the environment is the definition of: A. Environmental toxicology

B. Ecotoxicology

C. Environmental health toxicology

D. Risk assessment

14. An example of an area source of air emissions would be:

A. A volcano

B. A moving car

C. A gas station

D. A power plant

15. Which of the following is considered to be âgood up high and bad nearbyâ?

A. Ozone

B. Carbon monoxide

C. Carbon dioxide

D. Sulfur dioxide

16. Which of the following water disinfectants is safest from the perspective of not producing any known DBPs?

A. Chlorine

B. Chloramine

C. Ozone

D. UV

17. The most significant anthropogenic source of carbon monoxide would be classified as a:

A. Point source

B. Area source

C. Mobile source

D. Natural source

18. According to Genius (2006), what do some scientists believe is the most frequent cause of childhood cancer and leukemia?

A. Pharmaceuticals in drinking water

B. Exposure to diuretics in utero

C. Prenatal exposure to carbon monoxide and other industry emissions

D. Neonatal exposure to polyvinylchloride (PVC) plastic

19. In the Genius (2006) article, what did the scientists who published in the journal Science discover about the possible transgenerational impact of exposure to environmental toxicants in pregnancy?

A. Epigenetic mechanisms may permanently alter the germ-line and genetic traits of offspring of an exposed individual

B. Epigenetic changes die out after three successive generations of offspring

C. Epigenetic changes only occur when a toxicant is an endocrine disruptor

D. Epigenetic changes never take place when the toxicant is a pesticide or fungicide

20. According to the article by Chemnick and Climatewire (2013), âSoggy Vancouver Island in British Columbia has become an unlikely new home for Cryptococcus gattii, a tropical and subtropical yeast-based fungus.â What health effect does this yeast-based fungus have on humans when it is inhaled?

A. None

B. Triggers asthma attacks

C. Causes a kind of meningitis

D. Eventually leads to lung cancer

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ENSC 201 Lecture Notes - Lecture 8: Lead, Bioavailability, Methylmercury

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