Drinking water herbicide contamination

The drinking water maximum contaminant level (MCL) set by the USEPA for altrazine is 0.003 mg/L and its Reference Dose (RfD) is 3.5 ingAcg-d. How many liters of water containing atrazine at its MCL would a person have to drink each day to e.xceed the RfD for this triazine herbicide ... 

PCP has a negative effect on a number of aquatic life forms. Since 1987 PCP has been banned for herbicide and consumer uses, though it continues to be used for industrial applications, most notably as a wood preservative. Since 1992 the maximum contaminant level for drinking water has been set at 1 ppb. 

Both atrazine and metolachlor are classified as potential human carcinogens by the USEPA, which has established a maximum contaminant level in drinking water of 3000 ng/L [78]. The maximum concentrations of atrazine and metolachlor measured in the 1994-2000 Great Lakes survey were 1039 ng/L and 736 ng/L, respectively. The effects of long-term, low-level concentrations of atrazine and metolachlor on aquatic ecosystems are largely unknown [79]. The Canadian guidelines for the protection of aquatic fife and drinking water (Table 8) were not exceeded for either of these herbicides [80-83]. 

Because of its widespread use as a herbicide, the possibility exists of substantial paraquat contamination of food. Drinking water contamination by paraquat has also been observed. The chronic effects of exposure to low levels of paraquat over extended periods of time are not well known. Acute exposure of animals to paraquat aerosols causes pulmonary fibrosis, and the lungs are affected even when exposure is through nonpulmonary routes. Paraquat affects enzyme activity. Acute exposure may cause variations in the levels of catecholamine, glucose, and insulin. 

In the late 1970s HPLC provided an ideal tool for the analysis of pollutants and other environmental contaminants. Techniques were developed for analyzing chlorophenols, pesticide residues, and metabolites in drinking water and soil (parts per trillion) and trace organics in river water and marine sediments, and for monitoring industrial waste water and polynuclear aromatics in air. Techniques were also developed for determining fungicides and their decomposition products and herbicide metabolites in plants and animals. 

Use of granular activated carbon (GAC) is considered to be the best currently available technology for removing low-solubility contaminants such as disinfection by-products (usually from chlorination) that include trihalomethanes (THM), detergents, pesticides, herbicides, polyaromatic hydrocarbons, and some trace metals. The amendments to the Safe Drinking Water Act. state that other treatment technologies must be at least as effective as GAC [66]. 

Picloram is either a colorless powder or crystalline solid having very low vapor pressure, making inhalation exposure unlikely unless the dust is inhaled. Exposure to picloram occurs mainly through its manufacture and its use as a herbicide in forests. Environmental exposures in humans occur when forest visitors or others not directly involved in spray operations come in contact with spray or sprayed foliage, inhale spray mist, eat plants or animals contaminated with the herbicide, or drink water containing the herbicide. A suggested no-adverse-effect level is 1.05 mg 1. ... 

The sources of lipophilic/hydrophilic chemical exposure include environmental pollution (air, water, and soil contamination), pesticide, herbicide, and fertilizer residues in foods and drinking water, excipients (non-active additives such as colors, flavors, rheological agents, etc,) in foods and pharmaceuticals, industrial chemicals, household chemical products, personal care products, cosmetics, and environmentally synthesized chemicals that are formed from reactions with released chemicals with each other and with naturally present species. 

Non-point sources of 2,4-dichlorophenol and 2,4,5-trichlorophenol are mainly agricultural, since the phenoxy herbicides are hydrolyzed back to the phenols with a lifetime of about a week near 20°C. A minor local source of chlorophenols is chlorination of raw drinking water, which is contaminated with phenol (see Chapter 10). The most important chlorinated phenol is the pentachloro congener. 

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