Environmental lead exposure assessment for children from pre-1970's housing in St. John's, NL

Abstract

Environmental media samples from residential properties throughout St. John’s, NL were collected to examine the amount of lead contamination across housing age categories, as previous studies indicated that environmental lead levels on residential properties are above national guidelines, particularly on older properties. Methods: Environmental media samples were collected from properties participating in the study. 194 study households were sampled, representing 249 participants aged 6 months to 6 years. These included soil, indoor dust, indoor tap water, interior and exterior paint chips and garden produce samples. Statistical analyses examined the relationship between housing age category and strong-acid extractable lead levels in media samples, as well as, between media and existing data on children's blood lead levels. A bioaccessibility analysis was also undertaken for soil lead. Results: Significantly higher (p <0.0001) near-total lead concentrations were found for pre-1970 homes compared to reference post-1980 homes for dust, soil, water post-stagnation and paint. Overall the lead content of household floor dust was found to be correlated with concentrations in paint chips and soil, and to be weakly correlated to children’s blood lead levels (p <0.0001, r = 0.13). There was also a weak relationship on correlation analysis for tap water stagnation levels 1,2 and 4 and blood lead levels, as well as for our housing age category of pre-1970. Results of a 1 M HNO3 bioaccessibility method had a strong positively correlation to near-total lead concentrations, and only weakly correlated to other soil properties of CEC content: Mg and K for dripline soil samples. Conclusion: There are elevated levels of lead in indoor dust, soils and tap water of residential properties throughout St. John’s, which may represent an exposure risk to children’s health.