human exposure. short-term acute effects of ddt on humans are limited, however long-term exposure has been associated with chronic health effects including increased risk of cancer and diabetes, reduced reproductive success, and neurological disease. dioxins are unintentional by-products of high-temperature processes, such as incomplete combustion and pesticide production. dioxins are typically emitted from the burning of hospital waste, municipal waste, and hazardous waste, along with automobile emissions, peat, coal, and wood. dioxins have been associated with several adverse effects in humans, including immune and enzyme disorders, chloracne, and are classified as a possible human carcinogen. in laboratory studies of dioxin effects an increase in birth defects and stillbirths, and lethal exposure have been associated with the substances. food, particularly from animals, is the principal source of human exposure to dioxins. dioxins were present in agent orange, which was used by the united states in chemical warfare against vietnam and caused devastating multi-generational effects in both vietnamese and american civilians. polychlorinated dibenzofurans are by-products of high-temperature processes, such as incomplete combustion after waste incineration or in automobiles, pesticide production, and polychlorinated biphenyl production. structurally similar to dioxins, the two compounds share toxic effects. furans persist in the environment and classified as possible human carcinogens. human exposure to furans primarily results from food, particularly animal products. new pops on the stockholm convention list since 2001, this list has been expanded to include some polycyclic aromatic hydrocarbons (pahs), brominated flame retardants, and other compounds. additions to the initial 2001 stockholm convention list are the following pops: chlordecone, a synthetic chlorinated organic compound, is primarily used as an agricultural pesticide, related to ddt and mirex. chlordecone is toxic to aquatic organisms, and classified as a possible human carcinogen. many countries have banned chlordecone sale and use, or intend to phase out stockpiles and wastes. α-hexachlorocyclohexane (α-hch) and β-hexachlorocyclohexane (β-hch) are insecticides as well as by-products in the production of lindane. large stockpiles of hch isomers exist in the environment. α-hch and β-hch are highly persistent in the water of colder regions. α-hch and β-hch has been linked parkinson's and alzheimer's disease. hexabromodiphenyl ether (hexabde) and heptabromodiphenyl ether (heptabde) are main components of commercial octabromodiphenyl ether (octabde). commercial octabde is highly persistent in the environment, whose only degradation pathway is through debromination and the production of bromodiphenyl ethers, which can increase toxicity. lindane (γ-hexachlorocyclohexane), a pesticide used as a broad spectrum insecticide for seed, soil, leaf, tree and wood treatment, and against ectoparasites in animals and humans (head lice and scabies). lindane rapidly bioconcentrates. it is immunotoxic, neurotoxic, carcinogenic, linked to liver and kidney damage as well as adverse reproductive and developmental effects in laboratory animals and aquatic organisms. production of lindane unintentionally produces two other pops α-hch and β-hch. pentachlorobenzene (pecb), is a pesticide and unintentional byproduct. pecb has also been used in pcb products, dyestuff carriers, as a fungicide, a flame retardant, and a chemical intermediate. pecb is moderately toxic to humans, while highly toxic to aquatic organisms. tetrabromodiphenyl ether (tetrabde) and pentabromodiphenyl ether (pentabde) are industrial chemicals and the main components of commercial pentabromodiphenyl ether (pentabde). pentabde has been detected in humans in all regions of the world. perfluorooctanesulfonic acid (pfos) and its salts are used in the production of fluoropolymers. pfos and related compounds are extremely persistent, bioaccumulating and biomagnifying. the negative effects of trace levels of pfos have not been established. endosulfans are insecticides to control pests on crops such coffee, cotton, rice and sorghum and soybeans, tsetse flies, ectoparasites of cattle. they are used as a wood preservative. global use and manufacturing of endosulfan has been banned under the stockholm convention in 2011, although many countries had previously banned or introduced phase-outs of the chemical when the ban was announced. toxic to humans and aquatic and terrestrial organisms, linked to congenital physical disorders, mental retardation, and death. endosulfans' negative health effects are primarily liked to its endocrine disrupting capacity acting as an antiandrogen. hexabromocyclododecane (hbcd) is a brominated flame retardant primarily used in thermal insulation in the building industry. hbcd is persistent, toxic and ecotoxic, with bioaccumulative and long-range transport properties. health effects pop exposure may cause developmental defects, chronic illnesses, and death. some are carcinogens per iarc, possibly including breast cancer. many pops are capable of endocrine disruption within the reproductive system, the central nervous system, or the immune system. people and animals are exposed to pops mostly through their diet, occupationally, or while growing in the womb. for humans not exposed to pops through accidental or occupational means, over 90% of exposure comes from animal product foods due to bioaccumulation in fat tissues and bioaccumulate through the food chain. in general, pop serum levels increase with age and tend to be higher in females than males. studies have investigated the correlation between low level exposure of pops and various diseases. in order to assess disease risk due to pops in a particular location, government agencies may produce a human health risk assessment which takes into account the pollutants' bioavailability and their dose-response relationships. endocrine disruption the majority of pops are known to disrupt normal functioning of the endocrine system. low level exposure to pops during critical developmental periods of fetus, newborn and child can have a lasting effect throughout their lifespan. a 2002 study summarizes data on endocrine disruption and health complications from exposure to pops during critical developmental stages in an organism's lifespan. the study aimed to answer the question whether or not chronic, low level exposure to pops can have a health impact on the endocrine system and development of organisms from different species. the study found that exposure of pops during a critical developmental time frame can produce a permanent changes in the organisms path of development. exposure of pops during non-critical developmental time frames may not lead to detectable diseases and health complications later in their life. in wildlife, the critical development time frames are in utero, in ovo, and during reproductive periods. in humans, the critical development timeframe is during fetal development. reproductive system the same study in 2002 with evidence of a link from pops to endocrine disruption also linked low dose exposure of pops to reproductive health effects. the study stated that pop exposure can lead to negative health effects especially in the male reproductive system, such as decreased sperm quality and quantity, altered sex ratio and early puberty onset. for females exposed to pops, altered reproductive tissues and pregnancy outcomes as well as endometriosis have been reported. gestational weight gain and newborn head circumference a greek study from 2014 investigated the link between maternal weight gain during pregnancy, their pcb-exposure level and pcb level in their newborn infants, their birth weight, gestational age, and head circumference. the lower the birth weight and head circumference of the infants was, the higher pop levels during prenatal development had been, but only if mothers had either excessive or inadequate weight gain during pregnancy. no correlation between pop exposure and gestational age was found. a 2013 case-control study conducted 2009 in indian mothers and their offspring showed prenatal exposure of two types of organochlorine pesticides (hch, ddt and dde) impaired the growth of the fetus, reduced the birth weight, length, head circumference and chest circumference. health effects of pfas this section is an excerpt from per- and polyfluoroalkyl substances § human health concerns associated with pfass. effects of exposure to pfass on human health hormone-disrupting chemicals, including pfass, are linked with rapid declines in human fertility. in a meta-analysis for associations between pfass and human clinical biomarkers for liver injury, authors considered both pfas effects on liver biomarkers and histological data from rodent experimental studies and concluded that evidence exists showing that pfoa, perfluorohexanesulfonic acid (pfhxs), and perfluorononanoic acid (pfna) are hepatotoxic to humans. many comprehensive epidemiological studies linking adverse human health effects to pfass, particularly pfoa, come from the c8 science panel. the panel was formed as part of a contingency to a class action lawsuit brought by communities in the ohio river valley against dupont in response to landfill and wastewater dumping of pfas-laden material from dupont's west virginia washington works plant. the panel measured pfoa (also known as c8) serum concentrations in 69,000 individuals from around dupont's washington works plant and found a mean concentration of 83.0 ng/ml, compared to 4 ng/ml in a standard population of americans. this panel reported probable links between elevated pfoa blood concentration and hypercholesterolemia, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer as well as pregnancy-induced hypertension and preeclampsia. additive and synergistic effects evaluation of the effects of pops on health is very challenging in the laboratory setting. for example, for organisms exposed to a mixture of pops, the effects are assumed to be additive. mixtures of pops can in principle produce synergistic effects. with synergistic effects, the toxicity of each compound is enhanced (or depressed) by the presence of other compounds in the mixture. when put together, the effects can far exceed the approximated additive effects of the pop compound mixture. in urban areas and indoor environments traditionally it was thought that human exposure to pops occurred primarily through food, however indoor pollution patterns that characterize certain pops have challenged this notion. recent studies of indoor dust and air have implicated indoor environments as a major sources for human exposure via inhalation and ingestion. furthermore, significant indoor pop pollution must be a major route of human pop exposure, considering the modern trend in spending larger proportions of life indoors. several studies have shown that indoor (air and dust) pop levels to exceed outdoor (air and soil) pop concentrations. in rainwater this section is an excerpt from per- and polyfluoroalkyl substances § prevalence in rainwater. in 2022 it was found that levels of at least four perfluoroalkyl acids (pfaas) in rainwater worldwide ubiquitously and often greatly exceeded the epa's lifetime drinking water health advisories as well as comparable danish, dutch, and european union safety standards, leading researchers to conclude that "the global spread of these four pfaas in the atmosphere has led to the planetary boundary for chemical pollution being exceeded". there are some moves to restrict and replace their use. in cosmetics and personal care products per- and polyfluoroalkyl substances (pfas) are a class of about 9,000 synthetic organofluorine compounds that have multiple highly toxic fluorine atoms attached to an alkyl chain. pfas are used in the manufacture of a wide range of products such as food packaging and clothing. they are also used by major companies of the cosmetics industry in a wide range of cosmetics, including lipstick, eye liner, mascara, foundation, concealer, lip balm, blush, nail polish and other such products. a 2021 study tested 231 makeup and personal care products and found organic fluorine, an indicator of pfas, in more than half of the samples. high levels of fluorine were most commonly identified in waterproof mascara (82% of brands tested), foundations (63%), and liquid lipstick (62%). since pfas compounds are highly mobile, they are readily absorbed through human skin and through tear ducts, and such products on lips are often unwittingly ingested. manufacturers often fail to label their products as containing pfas, which makes it difficult for cosmetics consumers to avoid products containing pfas. control and removal in the environment current studies aimed at minimizing pops in the environment are investigating their behavior in photocatalytic oxidation reactions. pops that are found in humans and in aquatic environments the most are the main subjects of these experiments. aromatic and aliphatic degradation products have been identified in these reactions. photochemical degradation is negligible compared to photocatalytic degradation. a method of removal of pops from marine environments that has been explored is adsorption. it occurs when an absorbable solute comes into contact with a solid with a porous surface structure. this technique was investigated by mohamed nageeb rashed of aswan university, egypt. current efforts are more focused on banning the use and production of pops worldwide rather than removal of pops.