6 Source and Fate of Perchlorate in the Environment: A Grave …
145
iodine uptake inhibition is very detrimental for the foetus in the mother’s womb too.
ClO 4
− occurrence in pregnant women reduces the synthesis of thyroid hormones,
and consequently, placental transfer of iodine is decreased in the foetus. It may cause
neurobehavioural problems in infant and children in future (Bansal et al. 2009; Leung
et al. 2010). Clinical studies and studies conducted on animals indicate that effect of
ClO 4
− depends on dosage, and thyroid function of human may be disrupted by large
doses of ClO 4
− only (Srinivasan and Viraraghavan 2009).
6.5.2 Impacts of Perchlorate Toxicity on Environment
Very few ecological data are available on the exposure and impacts of perchlorate toxicity on the environment (Smith et al. 2001). For example, to understand
impact of toxicity of ClO 4
− on fishes, five-day acute toxicity test was carried out on
mosquitofish (Gambusia holbrooki) adults; they were exposed to aqueous sodium
perchlorate at 1, 10 and 100 mg/L, and their growth was studied (Park et al. 2006).
Growth was enhanced at 1 mg/L but seized at 10 mg/L. Study carried out on zebrafish
in water containing ammonium perchlorate at 0, 18 and 677 mg/L for up to eight
weeks reveals that ClO 4
− does not accumulate in whole fish, and impact of extrathyroidal toxicity results in thyroid follicle hypertrophy, angiogenesis hyperplasia and
colloid depletion (Patino et al. 2003). These results suggest that, at environmentally relevant concentrations, ClO 4
− does not induce acutely toxic effects, but higher
dosage for longer period may lead to hormonal effects on health of species.
6.6 Standard and Measurement of Perchlorate in Water
6.6.1 Standard of Perchlorate in Water
The current health advisory level for ClO 4
− is set at 15 µg/L based on the reference
dose recommended by US EPA (Wilkin et al. 2007). EPA calculated a tap water
screening level of 11 µg/L for perchlorate and perchlorate salts as per EPA, 2013.
The World Health Organization (WHO) established provisional maximum tolerable
daily intake (PMTDI) of 0.01 mg/kg body weight for ClO 4
− (Coates et al. 1999).
The current California regulatory standard for perchlorate in water is 6 ppb. (http://
www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Perchlorate.shtml).
145
iodine uptake inhibition is very detrimental for the foetus in the mother’s womb too.
ClO 4
− occurrence in pregnant women reduces the synthesis of thyroid hormones,
and consequently, placental transfer of iodine is decreased in the foetus. It may cause
neurobehavioural problems in infant and children in future (Bansal et al. 2009; Leung
et al. 2010). Clinical studies and studies conducted on animals indicate that effect of
ClO 4
− depends on dosage, and thyroid function of human may be disrupted by large
doses of ClO 4
− only (Srinivasan and Viraraghavan 2009).
6.5.2 Impacts of Perchlorate Toxicity on Environment
Very few ecological data are available on the exposure and impacts of perchlorate toxicity on the environment (Smith et al. 2001). For example, to understand
impact of toxicity of ClO 4
− on fishes, five-day acute toxicity test was carried out on
mosquitofish (Gambusia holbrooki) adults; they were exposed to aqueous sodium
perchlorate at 1, 10 and 100 mg/L, and their growth was studied (Park et al. 2006).
Growth was enhanced at 1 mg/L but seized at 10 mg/L. Study carried out on zebrafish
in water containing ammonium perchlorate at 0, 18 and 677 mg/L for up to eight
weeks reveals that ClO 4
− does not accumulate in whole fish, and impact of extrathyroidal toxicity results in thyroid follicle hypertrophy, angiogenesis hyperplasia and
colloid depletion (Patino et al. 2003). These results suggest that, at environmentally relevant concentrations, ClO 4
− does not induce acutely toxic effects, but higher
dosage for longer period may lead to hormonal effects on health of species.
6.6 Standard and Measurement of Perchlorate in Water
6.6.1 Standard of Perchlorate in Water
The current health advisory level for ClO 4
− is set at 15 µg/L based on the reference
dose recommended by US EPA (Wilkin et al. 2007). EPA calculated a tap water
screening level of 11 µg/L for perchlorate and perchlorate salts as per EPA, 2013.
The World Health Organization (WHO) established provisional maximum tolerable
daily intake (PMTDI) of 0.01 mg/kg body weight for ClO 4
− (Coates et al. 1999).
The current California regulatory standard for perchlorate in water is 6 ppb. (http://
www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Perchlorate.shtml).