lecture-4-chemical-hazards-and-human-health

Endocrine Disruptors

Chemical substances that interfere with the endocrine system by mimicking or blocking hormones (altering the production, transport and metabolism of hormones), altering the appearance of some genes, (exposed from animal studies) -bind to hormone receptors

DES (diethylstilbesteol)- example of endocrine disruptors

Synthetic estrogen used to prevent spontaneous abortion, associated with adverse health effects in offspring of women who took it during pregnancy. gives rise to teratogenic effects (given in early pregnancy until 35 weeks) (one million women took in1960-1970)

Impacts on the daughters whose mothers took DES

Reproductive organ dysfunction, abnormal pregnancies, reduced fertility, carcinoma, and immune system disorders

Health reproductive implications of endocrine disruptors

Feminization of males, changes in sexual behavior, birth defects (malformation), varied time in puberty, cancer of mammary glans, thyroid dysfunction- produced more thyroid stimulating hormone

Examples of feminization of males

Frogs changing genders and roosters changing voice

Neurobehavioral implications of Endocrine disruptors

Prenatal and early post-natal exposures

PCBS (Polychlorinated biphenyls)- impaired learning in non humans, delayed psychmotor development, distracted, poor IQ tests

Organophosphates- brain development (hindrances on size)

Case Study: Pesticides (organophosphates) and Children

Per research, exposure to pesticides hinder the development of intelligence and motor skills of young children

Example: two yaqui indian prescholars in Mexico (1998) -one frequently exposed to pesticides and other rarely exposed to it (variation in drawing)

Chemical body burdens

Quantity of chemicals accumulated in the body. Study happens from populational perspective. Body burdens aren’t stable over time because chemicals are removed and released such as peeing and exhaling through mechanisms. cant detect in low conc

Biomonitoring

Process of measuring the quantity of chemicals accumulated (body burdens in the body through analysis of blood, fat, and urine samples.

Tips to reduce body burdens

Exercise, filter air and water, eating lower in food chain (less meat, more grains, more fruits and vegetables-less chemicals)

Examples of organochlorine substances

Dioxins, DDT, Phthalate and Bisphenol A

Dioxins-endocrine disruptor

Toxic chemical compounds formed during combustion (forest fires, incineration, backyard trash) and manufacturing processes (herbicides), group of chemical compounds with similar chemical structure

2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD)

The most toxic and the most studied dioxin (more chlorine, the bigger toxicity)- the chemical becomes less soluble in water and more soluble in fats (can penetrate the plasma membrane and enter the cell)- accumulate in fatty tissue

Bioaccumulation- Dioxins

Accumulation of chemicals in specific tissues over time, while biomagnification refers to the increase in concentration of chemicals in the food chain.

Biomagnification

Accumulate the buildup of the chemical in the food chain (smaller conc at the bottom of the food chain in tissues and higher conc as you go higher in food chain. exposed to before we were born

POP (Persistent Organic Pollutants)

Chemicals that are difficult to excrete from the body and can persist in the environment for long periods, such as dioxins. difficult to excrete

Chloracne

Skin condition caused by exposure to certain chlorinated compounds, like dioxins.

DDT (dichloro-diphenyl-trichloro-ethane)-endocrine disruptor

Agricultural pesticide used for mosquito control, associated with various health and environmental impacts-2 benezen rings. Travels long distances, very persistant, found in fatty tissue and breast milk, grasshopper effect

effects of DDT

cariconogen, reproductive system damage, liver damage, nervous system affected due to long exposure to ddt

Carcinogen

Substances that can cause cancer, such as DDT which has been linked to breast cancer.

DDT bans in what countries

Banned in US, Canada, Chile, Cuba, Liechtenstein, Korea, Poland, Singapore, Switzerland and other countries

DDT is permitted for import in what countries

Thailand, India, Tanzania, Kenya, Mexico, Sri Lanka, Bolivia, Mauritius, Nepal, Sudan, Guinea, Bhutan, Ethiopia, Vietnam, Phillipines

Phthalate

Chemicals used in the production of plastics, known for their moldable and soft properties, commonly found in baby toys and medical plastics. release the most dioxin

Bisphenol A

Another chemical used in making plastics, which can slowly leach into the air or container contents, with potential health effects as an endocrine disruptor and linked to developmental issues and obesity.

Malaria

A mosquito-borne infectious disease that can be deadly, with mosquitoes developing resistance to pesticides like DDT, leading to challenges in controlling the disease.

Health effects of phtatalates and bisphenol-A

Both are endocrine disruptors, hinders developmental effects in male lab animals and male infants. Can be evidence to obesity in lab animals and people