Lead Testing for Garden Soils in New York City.

Testing of nearly 3,000 community and home garden soils in New York City revealed severe lead contamination, particularly in northern Brooklyn and lower Manhattan – the oldest urban center with a long industrial history. A lead map for New York City has been generated and color coded based on median lead concentrations in each zip code. Nearly half of the samples submitted by residents contained >400 ppm lead, while ~20% more than 1200 ppm. In general, home gardens are much more contaminated than community gardens. There is often large variability within the same garden. The elevated lead levels in the garden soil pose significant risk to gardeners and even more importantly to kids who has more exposure through incidental ingestion. Lead is also more harmful to children whose neurological systems are still developing. Testing the soil is the first critical step in understanding the health risk and taking measures to mitigate the risk for urban population. While available simple lead testing methods (such as X-ray Fluorescence, some lead kits) often have larger uncertainties, they have the potential to provide affordable and easier access for widespread large scale testing that can quickly inform gardeners the soil contamination levels, thereby take respective actions to mitigate the exposure in the short term. This is especially important for low income communities which unfortunately are often the most contaminated neighborhoods. We argue that strict lab testing is not a priority as the exact guideline values (e.g., 400 ppm) are mostly subjective in nature. With the current state of knowledge on dose response relationship, very precise lead concentration value is not warranted. In addition, the highly variable soil lead concentrations in small scale and the variability in the bioavailable lead also defeat the purpose for very precise values collected in certified labs.