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Lead line in rodents: an old sign of lead intoxication turned into a new method for environmental surveillance

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The “lead line” was described by Henry Burton in 1840. Rodents are used as sentinels to monitor environmental pollution, but their teeth have not been used to determine lead. To determine whether lead deposits can be observed in the teeth of lead-exposed animals, since the gingival deposits known as “lead line” would likely have a correlate in the calcified tissue to which the gums are opposed during life. Male Wistar rats were exposed to lead in the drinking water (30 mg/L) since birth until 60 days-old. Molars and the incisors of each hemimandible were analyzed by scanning electron microscopy (SEM) on regular and backscattered electrons (BSE) mode. Elements were determined using electron dispersive spectroscopy (EDS). Clean cervical margins were observed on control teeth, as opposed to the findings of extensive deposits on lead-exposed animals, even in hemimandibles that had been exhumed after being buried for 90 days. BSE/EDS indicated that those deposits were an exogenous material compatible with lead sulfite. Presence of calcium, phosphorus, magnesium, carbon, lead, and oxygen is presented. Lead-exposed animals presented marked root resorption. The lead deposits characterized here for the first time show that the “lead line” seen in gums has a calcified tissue counterpart, that is detectable post-mortem even in animals exposed to a low dose of lead. This is likely a good method to detect undue lead exposure and will likely have wide application for pollution surveillance using sentinels.

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This study was supported by the Conselho Nacional de Pesquisa, CNPq, and the (Brazilian) National Research Council.

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Correspondence to Fellipe Augusto Tocchini de Figueiredo.

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The authors declare that they have no competing financial interests. The authors declare that they have no conflict of interest.

Additional information

Communicated by: Philippe Garrigues

Electronic supplementary material

Supplemental figure 1

Representative maps of the signals of different elements detected in control teeth (A), and in teeth of lead-exposed animals (B). (GIF 896 kb)

High Resolution (TIFF 914 kb)

Supplemental Table 1

Signal intensities obtained in 2 areas of the teeth (cervical and incisal) in control (n=7) and Pb-exposed animals (n=7). Statically significant differences were not found (DOC 29.5 kb)

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de Figueiredo, F.A.T., Ramos, J., Kawakita, E.R.H. et al. Lead line in rodents: an old sign of lead intoxication turned into a new method for environmental surveillance. Environ Sci Pollut Res 23, 21475–21484 (2016). https://doi.org/10.1007/s11356-016-7336-3

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  • Lead line
  • Sentinels
  • Dental enamel
  • Lead
  • Tooth
  • Environmental monitoring