be around 80% whereas 20% is coming from hospitals. individuals may add ppcps to the environment through waste excretion and bathing as well as by directly disposing of unused medications to septic tanks, sewers, or trash. because ppcps tend to dissolve relatively easily and do not evaporate at normal temperatures, they often end up in soil and water bodies. some ppcps are broken down or processed easily by a human or animal body and/or degrade quickly in the environment. however, others do not break down or degrade easily. the likelihood or ease with which an individual substance will break down depends on its chemical makeup and the metabolic pathway of the compound. in rivers in 2022, the most comprehensive study of pharmaceutical pollution of the world's rivers finds that it threatens "environmental and/or human health in more than a quarter of the studied locations". it investigated 1,052 sampling sites along 258 rivers in 104 countries, representing the river pollution of 470 million people. it found that "the most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing" and lists the most frequently detected and concentrated pharmaceuticals. locations of studied rivers/catchments (n = 137).points = groups of sampling sites across respective river catchments;shades of countries = total number of sampling sites. concentrations detection frequencies and number of active pharmaceutical ingredients detected cumulative concentrations of active pharmaceutical ingredients sites exceeding "safe" limits recreational drugs a study published in 2014 reported a spike in the levels of ecstasy, ketamine, caffeine and acetaminophen in nearby rivers coinciding with a taiwanese youth event attended by around 600,000 people. in 2018, shellfish in puget sound, waters that receive treated sewage from the seattle area, tested positive for oxycodone. the occurrence of pharmaceuticals and personal care products in wastewater is frequent and ubiquitous enough that ppcps in wastewater can be measured to estimate their use in a community. studies prior to 2006 a 2002 study by the u.s. geological survey found detectable quantities of one or more chemicals in 80 percent of a sampling of 139 susceptible streams in 30 states. the most common pharmaceuticals detected were nonprescription drugs; detergents, fire retardants, pesticides, natural and synthetic hormones, and an assortment of antibiotics and prescription medications were also found. a 2006 study found detectable concentrations of 28 pharmaceutical compounds in sewage treatment plant effluents, surface water, and sediment. the therapeutic classes included antibiotics, analgesics and anti-inflammatories, lipid regulators, beta-blockers, anti-convulsant, and steroid hormones. although most chemical concentrations were detected at low levels (nano-grams/liter (ng/l)), there are uncertainties that remain regarding the levels at which toxicity occurs and the risks of bioaccumulation of these pharmaceutical compounds. other besides the identified input from human medicine there appears diffuse pollution for example from pharmaceuticals used in agriculture, too. investigations in germany, france and scotland showed traces of ppcps upstream of waste water treatment plant effluents to rivers, too. the nopills report found that "the whole medicinal product chain needs to be considered for multi-point, targeted intervention". effects ppcps: shelves with tampons, women's sanitary towels, tooth brushes, health and body care products human the scope of human exposure to pharmaceuticals and personal care products from the environment is a complex function of many factors. these factors include the concentrations, types, and distribution of pharmaceuticals in the environment; the pharmacokinetics of each drug; the structural transformation of the chemical compounds either through metabolism or natural degradation processes; and the potential bioaccumulation of the drugs. more research is needed to determine the effects on humans of long-term exposure to low levels of ppcps. the full effects of mixtures of low concentrations of different ppcps is also unknown. "the u.s. epa risk assessment states that the acceptable daily intake (adi) of pharmaceuticals is around 0.0027 mg/kg‐day." due to the lack of research of toxicity guidelines and their effects on human health it is difficult to determine a healthy dosage for water contaminated by pharmaceuticals. "the pharmaceutical sample size tested does not give a full representation of human exposure. only 17 out of 3000 prescriptions are screened for in drinking water." in addition, "the epa and fda regulations state that a drug or chemical is not considered harmful until clear evidence shows that a substance causes harm". this means that we are not testing or screening for thousands of contaminants in our drinking water. health risk assessments have not been conducted to provide concrete evidence to link pharmaceutical contamination and adverse human health effects. "however adverse health outcomes are displayed in aquatic organisms. fish living near water treatment plants have been reported to be feminized." "some male fish started to develop ovaries and other feminized characteristic due to pharmaceutical pollution some species have decreased in population due to exposure of ee2 and other hormonal ecd substances." although research has shown that ppcps are present in water bodies throughout the world, no studies have shown a direct effect on human health. however, the absence of empirical data cannot rule out the possibility of adverse outcomes due to interactions or long-term exposures to these substances. because the amounts of these chemicals in the water supply may be in the parts per trillion or parts per billion, it is difficult to chemically determine the exact amounts present. many studies have therefore been focused to determining if the concentrations of these pharmaceuticals exist at or above the accepted daily intake (adi) at which the designed biological outcomes can occur. in addition to the growing concerns about human health risks from pharmaceutical drugs via environmental exposures, many researchers have speculated about the potential for inducing an antibiotic resistance. one study found 10 different antibiotics in sewage treatment effluents, surface water, and sediments. some microbiologists believe that if antibiotic concentrations are higher than the minimum inhibitory concentrations (mics) of a species of pathogenic bacteria, a selective pressure would be exerted and, as a result, antibiotic resistance would be selectively promoted. it has also been proven that at even sub-inhibitory concentrations (e.g., one-fourth of the mic), several antibiotics are able to have an effect on gene expression (e.g., as shown for the modulation of expression of toxin-encoding genes in staphylococcus aureus). for reference the mic of erythromycin that is effective against 90 percent of lab grown campylobacter bacteria, the most common food-borne pathogen in the united states, is 60 ng/ml. one study found that the average concentration of erythromycin, a commonly prescribed antibiotic, was 0.09 ng/ml in water treatment plant effluents,. additionally, transfer of genetic elements among bacteria has been observed under natural conditions in wastewater treatment plants, and selection of resistant bacteria has been documented in sewers receiving wastewaters from pharmaceutical plants. moreover, antibiotic resistant bacteria may also remain in sewage sludge and enter the food chain if the sludge is not incinerated but used as fertilizer on agricultural land. the relationship between risk perception and behavior is multifaceted. risk management is most effective once the motivation behind the behavior of disposing unused pharmaceuticals is understood. there was little correlation found between the perception of risk and knowledge regarding pharmaceutical waste according to a study conducted by cook and bellis in 2001. this study cautioned against the effectiveness of attempting to change the public's behavior on these health issues by warning them of the risks associated with their actions. it is advised to take careful measures to inform the public in a way that does not impart guilt but rather public awareness. for example, a study carried out by norlund and garvill in sweden (2003) that found that some people may make a personal sacrifice in terms of comfort because they feel that it would be helpful to reduce further environmental damage caused by the use of cars. awareness of air pollution problems was a factor in their decision to take action on a more environmentally favorable choice of transportation. thus, the goal of bound's project encapsulates whether the perception of risk associated with pharmaceuticals has an effect on the way in which medication is commonly disposed. in order to conduct this study, the pharmaceuticals were grouped by their therapeutic action in order to help participants identify them. the eight therapeutic groups are listed below: antibacterials, antidepressants, antihistamines, antiepileptics, hormone treatments, and lipid regulators. next, a survey was created to examine the disposal patterns of the participants and their perception of the existing risk or threat against the environment. respondents were asked the following questions in part one of the survey: 1. when and how they disposed of pharmaceuticals. 2. how they perceive the risk to the environment posed by pharmaceuticals. 3. to differentiate between the risks associated with different classed of pharmaceuticals. part two of the survey involved each of the eight pharmaceutical groups described above individually. finally, the third part asked information about the age, sex, profession, postcode, and education of participants. the sample size of participants was precise in comparison to the actual distribution of males and females in the uk: sample- 54.8 percent were female and 45.2 percent male vs. actual- the uk of 51.3 percent female to 48.7 percent male. results showed that when a medication must be discarded, 63.2 percent of participants throw them in a bin, 21.8 percent return them to a pharmacist, and 11.5 percent dispose of them via the toilet/sink, while the remaining 3.5 percent keep them. only half of the respondents felt like pharmaceuticals could potentially be harmful to the environment. upon examination of factors relevant to risk perception, there was no definite link found between perception and education or income. dr. bound noted that participation in altruistic activities such as environmental conservation groups may provide members with the ability to better grasp the effects of their actions in the environment. in regards to the aquatic environment, it is hard for one to perceive the favorable effects of properly disposing medication. there also exists the plausibility that a person's behavior will only be affected if there is a severe risk to themselves or humans as opposed to an environmental threat. even though there are serious threats of pharmaceutical pollution resulting in the feminization of certain fish, they have a lower priority because they are not easily understood or experienced by the general public. in jonathan p. bound's opinion, the provision of information about exactly how to go about disposing unused medication properly in conjunction with risk education may have a more positive and forceful effect. recommendations several recommendations and initiatives have been made to prevent pharmaceutical pollution in the environment. important practices include: educating patients on the importance of proper unused drug disposal, educating physicians and patients of proper drug disposal, encouraging pharmaceutical industries to implement strategies for proper disposal of drugs or recycling strategies, and requiring hospitals to implement better management practices for disposing pharmaceutical waste. first, it is imperative that patients become educated on pharmaceutical pollution and its hazardous effects on humans, animals, and the overall environment. by educating patients on proper disposal of unused drugs, steps are being taken to further prevent pharmaceutical waste in the environment. consumers should take precautions before tossing out drugs in the trash or flushing them down the toilet. community take-back programs have been set up for consumers to bring back unused drugs for proper disposal. another initiative is for pharmacies to serve as a take-back site for proper drug disposal such as implementing recycling bins for customers to bring back unused or expired medicines while they're shopping. in addition, medical foundations could receive these medicines to administer them to people who need them, while destroying those that are in excess or expired. furthermore, educating physicians and patients on the importance of proper drug disposal and the environmental concern will help further reduce pharmaceutical waste. also, implementing initiatives for hospitals to focus on better practices for hazardous waste disposal may prove to be beneficial. the us epa encourages hospitals to develop efficient pharmaceutical disposal practices by giving them grants. this incentive may be very beneficial to other hospitals worldwide. additionally, "it is critical for us to develop an analytical method of identifying, testing, and regulating the amount of pharmaceuticals in the water systems". data must be collected in order to accurately measure the prevalence of pharmaceuticals in drinking water. "multiple health risk assessments should be conducted to understand