Daily Archives: June 20, 2011

Los Angeles DWP Reuse Plant Proposed

Nice summary article of the proposed indirect reuse plant planned by the LA Department of Water and Power….following completion of a $2 million pilot study….LA hopes to avoid the “toilet to tap” label by following the template of the successful indirect reuse project of Orange County Water District.  Nice exposure for the consultant as well…..

Click here for the Contra Costa Times article.

Airborne Fluoride and Fluorosis: Studies in India and China

Two recent studies have found an association between airborne fluoride exposure and dental fluorosis….one study in India, and the other in China.  The abstracts below are courtesy of the National Library of Medicine….

Pandey J. & U. Pandey 2011. Fluoride Contamination and Fluorosis in Rural Community in the Vicinity of a Phosphate Fertilizer Factory in India. Bull Environ Contam Toxicol.  2011 Jun 18. 

Abstract (National Library of Medicine, Open Source)

We studied chronic fluoride intoxication in 10 villages of Udaipur receiving F emissions from phosphate fertilizer factories. Although fluoride remained below permissible limit in most of the drinking water samples, the incidence of fluorosis in adults as well as in children was surprisingly high. Khemli appeared to be the most affected village (with >48% cases) where, about 93% of 2 h air samples contained fluoride above 2.0 μg m(-3) and crops and vegetable F ranged from 27.5 to 143.4 μg g(-1). Concentrations of fluoride and inorganic P in urine showed asynchrony and were well linked with prevalence of fluorosis. The study indicated that air-borne fluoride was the major factor for higher prevalence of fluorosis in these rural areas.

Ruan, J.P., Bardsen, A., Astrom, A.N., Huang, R.Z., Wang, Z.L., and Bjorvatn, K. 2007. Dental fluorosis in children in areas with fluoride-polluted air, high-fluoride water, and low-fluoride water as well as low-fluoride air: a study of deciduous and permanent teeth in the Shaanxi province, China. Acta Odontol Scand. Apr;65(2):65-71.

Abstract (National Library of Medicine, Open Source)

OBJECTIVE: The aim of the study was to assess dental fluorosis (DF) in the deciduous and permanent teeth of children in areas with high-F coal (area A) and high-F water (area C) compared to children from area B, with low-F water and coal.

MATERIAL AND METHODS: 596 children were examined. DF was assessed by TF-score. F-content of indoor air, drinking water, coal, tea, rice, and maize was analyzed.

RESULTS: F-content of air and coal ranged from 3.2 microg/m(3) and 25.8 mg/kg (area B), 3.8 microg/m(3) and 36.3 mg/kg (area C) to 56.8 microg/m(3) and 713.1 mg/kg (area A). Likewise, mean F-content of water ranged from approximately 0.50 mg/l (areas A and B) to 3.64 mg/l (area C). F-content of tea leaves was similar in all three areas. Maize and rice contained <5 mg F/kg. Prevalence of primary teeth with DF was 49.1%, 2.0%, and 66.8% in areas A, B, and C, respectively. Similarly, DF was found in 96.7% (area A), 19.6% (area B), and 94.4% (area C) of the permanent teeth. Severe fluorosis (TF > or = 5) was found in area A (47.0%) and area C (36.1%) (p<0.01). Early erupting teeth had slightly higher mean TF-scores in area A than in area C.

CONCLUSIONS: DF was prevalent in both dentitions in areas A and C. Similarity in percentages of DF may indicate that indoor air with approximately 60 microg F/m(3) and drinking water with 3.6 mg F/L are similarly toxic to developing permanent teeth. The percentage of deciduous teeth with DF was significantly lower in area A compared to area C. Where low-F coal and low-F water were used (area B), approximately 20% of permanent teeth had DF, indicating a relatively low tolerance to fluoride in Chinese children brought up under the present living conditions.