Approach on Detection of Situation of Potential Risk to Health, Related to Water Quality: An Example

Abstract

This work describes the approach of a situation of potential risk to health due to nitrate contamination in water intended for human consumption, found in a study conducted in 88 municipalities in the Northeast region of the State of São Paulo (Brazil). 4,347 public water supply samples were analysed for 21 physico-chemical and 2 microbiological parameters. A municipality was distinguished from the others with regard to higher nitrate levels, while the principal components analysis showed that it belonged to a group of 14 municipalities (nitrate group). The Sanitary Surveillance Group was then contacted and, after confirmatory tests in new public water supply samples, analyses were performed on water samples from 16 wells in the county. The groundwater contamination was found, and technical meetings were held. One of the deliberations was the repetition of water analyses of the 16 wells. Consolidated results showed that the 5 wells had nitrate levels above the maximum value permitted by legislation. To mitigate nitrate groundwater contamination of that municipality actions are being taken as a result of 3 technical meetings already held. The other municipalities of the nitrate group are being monitored.

Analysis of Factors Involving Drinking Water Contamination by Glyphosate and/or Nitrate in Urban Areas

“…In present study the water from the city of Monte Azul Paulista exhibited a nitrate mean concentration equal to 3.5 mg L -1 . Nitrate contamination of water intended for human consumption has also been described for the neighboring city, Severínia [24]; in present study this city presented a similar physicochemical profile to Monte Azul Paulista (Fig. 4A) and nitrate mean concentration equal to 5.5 mg L -1 .…”

“…4B), with loadings 0.46, 0.44, 0.43, 0.40 and 0.38, respectively, but the contribution of glyphosate was also significant (loading 0.32). The strong influence of the chloride, magnesium, nitrate, conductivity and calcium variables on the PCA of region groundwater physicochemical parameters had already been observed in previous studies and was related to profiles of nitrate contaminated water [23,24]. Although part of the chloride present in tap water comes from the disinfection process by chlorination, the high positive correlation between nitrate/chloride (r = 0.857) suggests contamination by anthropic action, as well as the positive nitrate/conductivity correlation (r = 0.490).…”

“…A study carried out in the region, using 4,347 samples from "Proagua" and analyzing 23 parameters, mapped tap water quality and indicated the existence of a group of 14 cities with high nitrate levels in which Monte Azul Paulista and Severínia stood out. [23,24].…”

Concentrações de nitrato em águas de abastecimento público de 88 municípios da Rede Regional de Atenção à Saúde 13 do estado de São Paulo, Brasil

“…Considerando inicialmente que os dados das 4.347 amostras não apresentavam distribuições de Gauss, o cálculo dos coeficientes de correlação de Spearman (rs) para as cinco variáveis físico-químicas da Figura 1B indicou que as correlações mais significativas das concentrações de nitrato ocorriam com as concentrações de magnésio e cloreto (segunda coluna da Tabela 2). Contudo, a ACP das Figuras 1A e 1B e de análises de estudos anteriores 9 indicaram correlação significativa também com os valores de condutividade e com as concentrações de cálcio. De fato, se calcularmos os coeficientes de correlação linear (r) para as mesmas variáveis (n = 4.347), verifica-se um aumento nos valores para as correlações do nitrato com cálcio, magnésio e condutividade, mas uma diminuição na correlação com o cloreto (terceira coluna da Tabela 2).…”

“…Em particular, neste Estado existe preocupação com relação à presença de nitrato em águas de abastecimento, uma vez que contaminações de mananciais subterrâneos tem sido reportadas, como as ocorridas nos municípios de Marília 5 , Presidente Prudente 6 , Monte Azul Paulista 7 e Severínia 8,9 . O interesse da Saúde Pública frente à presença deste íon em águas destinadas ao consumo humano deve-se à ocorrência de metemoglobinemia em crianças até três meses de idade ("síndrome do bebê azul"): segundo a Organização Mundial da Saúde (OMS) 1 , estudos epidemiológicos não reportaram metemoglobinemia em áreas em que a água potável continha menos do que 50 mg L -1 de nitrato, NO 3 -(ou 11 mg L -1 , se expresso como nitrogênio-nitrato, N-NO 3 -).…”