Nitrate concentration in Community Water Systems (CWS) - Double bar chart

This double bar chart example was drawn on the base of picture "Nitrate Concentration (milligrams per liter; mg/ L) in Community Water Systems (CWS), Mean and Maximum by Year, New Mexico 1999-2012" from the New Mexico's Indicator-Based Information System (NM-IBIS) website.
"Nitrate toxicity is a preventable cause of methemoglobinemia (blue baby syndrome), especially in infants. Infants younger than 4 months of age are at greatest risk of toxicity from nitrate-contaminated drinking water.
These infants are more susceptible to developing methemoglobinemia because the pH of their gut is normally higher (less acidic) than in older children and adults. The higher pH enhances the conversion of ingested nitrate to the more toxic nitrite. The bacterial flora of a young infant's gut is also different from that found in older children and adults and might be more likely to convert ingested nitrate to nitrite. Gastroenteritis can increase body transformation of nitrate to nitrite and absorption into the bloodstream of nitrite from the large intestine.
A large proportion of hemoglobin in young infants is in the form of fetal hemoglobin. Fetal hemoglobin is more readily oxidized to methemoglobin (MHg) by nitrites than is adult hemoglobin. In addition, in infants, the enzyme (NADH-dependent methemoglobin reductase) responsible for reduction of formed MHg back to normal hemoglobin has only about half the activity it has in adults.
Symptoms such as shortness of breath and bluish skin coloring around the mouth, hands, or feet, can occur in infants rapidly over a period of days. If the condition is severe, it could lead to convulsions, coma, and even death, if untreated. Most older children and adults can take in larger amounts of nitrate without experiencing the same health effects as infants. However, pregnant women, nursing mothers, and people with low stomach acid conditions or those deficient in an enzyme that changes MHg back to normal hemoglobin are more susceptible to nitrate-induced methemoglobinemia and could be affected by water with nitrate levels above 10 mg/ L.
Adverse reproductive outcomes such as spontaneous abortions, intrauterine growth retardation, and various birth defects such as anencephaly have been reported in scientific literature from exposure to high nitrate levels in drinking water; however, the evidence is inconsistent.
Little is known about possible health effects from high nitrate level exposure over a long period of time. However, some studies suggest that there might be a risk of stomach, esophageal or bladder cancers in people with prolonged ingestion of high levels of nitrate. This might be due to the formation of nitrosoamines in the body following ingestion exposure to high levels of nitrate.
International Agency for Research on Cancer (IARC) classified ingested nitrate or nitrite as probably carcinogenic to humans (Group 2A) under conditions that result in formation of nitroso-compounds (e.g., nitrosoamines) in the body (endogenous nitrosation)." [ibis.health.state.nm.us/ indicator/ view/ CommWaterNitrates.MeanMax.Year.html]
The double bar graph example "Nitrate concentration in Community Water Systems (CWS)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Bar Graphs solution from the Graphs and Charts area of ConceptDraw Solution Park.