Week 3 Summary Toxicology Angela Reyes

Week 3 Summary ToxicologyAngela ReyesToxicology what levels of contaminants are harmful (dose-response relationship)Thresholds:LD50 = dose where 50% death rate occursLOAEL = Lowest Observable Adverse EffectNOAEL = NO Observabel Adverse Effect LevelMixtures rarely tested additive/synergistic possibilitiesExposure Assessment likely to exceed these levels guides policy making/regulationFactors Affecting ToxicityChemical properties, dose/time, species/age/sex, route of exposureBiological Processes: Absorption, Distribution, Metabolism ExcretionAgent Exposure Dose Skin/Lungs/GI Tract Internal Dose Bloodstream Target Organ Dose Organs & TissuesNon-Polar/Hydrophobic Cpds: easily absorbed, tend to build in fat BIOACCUMULATION (i.e. POPs Persistent Organic Pollutants)Polar/Hydrophilic Cpds: are NOT as readily absorbed & filtered from blood by kidney Major Routes of ExposureInhalation: lungs=SA water sol, high VP readily enter bloodstreamIngestion: food/water gut lining fat soluble cpds quickest to absorbDermis: skin=good barrier, BUT can absorb fat-soluble cpdsNo Contact: Energy radiation penetrate skin and damage DNA

Body De-Tox water sol through kidneys, less water-sol converted to water-solPhase I & II MetabolismPhase I add hook (-OH) cytochrome p450 increase H2O-solPhase II conjugate glutathione, sulfate, and glucuronic acids for excretion (urine)EDCs = Endocrine Disrupting Chemicals (production/transport/signaling/elimination)Most are estrogenic, primarily metabolic concernPlastics, pesticides, and some drugsBPA: plastics and canned foods mimics estrogen Pthalates: used to soften plastics cosmetics, flexible plastics, PVC flooring likely carcinogen, links to human rates of obesityPFOA and Fluorinate Telomers: non-stick cookware likely carcinogen bioaccumulation in SERUM, not fat infertility, mammary gland dvlpt, thyroid diseasePBDE and Brominated Flame Retardants: carpets, electronics liver/thyroid/neurological toxicityWhat Can We Do?Emphasize whole, plant-based foodsNever microwave in plastic containersChoose synthetic fragrance-free detergentsPay attention to plastic typesGMOs and Herbicide Toxicity RoundUp overuse created resistant