There are a number of thousands of palisades and the fire survivors came to depend on it: 80 milligrams of lead in each kilogram of soil.
Below this concentration, California has historically judged the sites safe enough for families to rebuild themselves and return home after a fire. In addition, according to state scientists, it is accompanied by a significant risk that children develop neurological problems from the example they inhabit accidentally, absorb through their skin and eat while playing outside.
In a New paper FridayHarvard environmental researchers argue that it is not strict enough. Scientists argue that the state health standard is not based on a solid science and should be around 55 milligrams per kilogram of soil (a measure also called “parts per million”).
“We are asked these questions every day, like all the other scientists …” Is it sure for my children? ” “Said Joseph Allen, main author of the newspaper and professor of the Harvard Th Chan School of Public Health who worked with the Fire survivors through the research program on the study of health. “I can’t look anymore in the eye, knowing what I know about these models, and saying yes.”
However, other researchers on soils and health said that it was a better confined debate to technical scientific articles, with few implications for the fire survivors wondering if their property is sure.
Here is what you need to know:
Why a stricter standard?
Lead can cause negative effects on health at practically all levels of exposure, so that California scientists Department of Toxic Substances Control have established their level of health for lead in residential soil, starting with a goal: the standard should prevent children from losing an IQ due to lead exposure.
To answer this, the department uses a computer model, in mind, which estimates the amount of lead in the body of a child who plays in dirt, mainly by accidentally eating dirt on their hands.
Then he determines what a fraction of lead that has entered the body actually made in the blood circulation.
From there, the DTSC estimates that 1 microgram of lead per deciliter of the blood leads to a loss of a point of Qi.
By searching in DTSC articles describing how he calculated the 80 mg / kg standard, Harvard researchers identified three problems.
First, they underline that the standard comes from an old version of the department model, lead 8. When DTSC has recalculated the number with the updated plugs 9, they obtained 70 mg / kg, but determined that the difference would not have a significant impact on the QI.
Harvard researchers argue that DTSC has no solid basis for this hypothesis.
Second, Harvard scientists warn that the main model depends despite other hypotheses. For example, the model determines the percentage of lead that enters the body is found in blood on the basis of a 1983 study on infants who consumed formulas contaminated by lead.
It is a very different situation from that of the soil, according to Harvard scientists, and even a slight change in this percentage can give a much more strict result of around 55 mg / kg. The same is true if the DTSC had to use a higher estimate for the quantity of dirt, on average, a child ingests per day.
Finally, Harvard researchers point out that the leads cause damage not only to the nervous system – for which the metric of IQ tries to account – but also to the bones, the kidneys and the heart. And not all children have the same risk. Children with other health problems can be more sensitive, as are 2 -year -old children compared to 6 -year -old children.
“The model occurs in the void,” said Lindsey Burghardt, Director of Sciences of the Harvard’s Center on the child in development and author of the newspaper. “But children … live in the context of their development environment where they have a number of different exhibitions and experiences, whether positive or negative.”
DTSC did not immediately respond to a request for comments.
What does this mean for fire survivors in the hope of going home?
Many soil health and environmental researchers say that the debate should not affect the fire survivors.
Given all the uncertainty of lead modeling – and the wide range of sensitivity that different children can have according to their health problems and the quantity they play in dirt – many researchers say that the residents concerned should focus on their own risks and consider lead levels as “much lower than standard differences”, “near the norm” and “much higher than the standard numbers.
For example, much higher levels in the ground which are about to be covered with a new concrete foundation may not have as much importance. The levels close to the standard in the courtyard of a homeless house do not matter if the residents are not passionate gardeners and always remove their shoes when they enter the house.
On the other hand, the levels even lower in the ground in an area where a 2 year old child likes to play in mud could present an unacceptable risk for a resident.
Seth John, professor of Earth Sciences at the USC, stressed that, while different lead hypotheses could lead to a much lower standard, the reverse is also true.
John also noted that the Federal Environmental Protection Agency standard is even higher at 200 mg / kg – which is down 400 mg / kg for playgrounds and 1,600 mg / kg for other residential areas simply a year ago. California only adopted its current standard in 2009.
Harvard scientists stress that this downward trend in the norm is due to the new science showing that children are more sensitive to lead than we thought before. Their update of 55 mg / kg, they say, is for the same reason.
The evaluation and analysis of the level of USC contaminants for the districts project team (Clean), with which John works to test the post-fire soil in the County of Los Angeles, said that 43% of the properties they tested exceed the standard of 80 mg / kg, while 57% exceeded 55 mg / kg.
How can fire survivors remain safe?
John also argued that the debate on the main standard distracted from the simple steps that residents can take to protect themselves and protect their children.
USC Clean continue to offer free floor tests For all residents of the County of Los Angeles – thanks in part to FIREAID FINANCE. The Los Angeles Public Health Department is Also offering free soil tests For residents in certain areas inside and in the wind of the fire scar from fire Eaton.
The department also offers Free lead blood test (As most insurance do) via Quest Labs for anyone concerned about their exhibition.
The soil researchers say that the most effective way to remedy the contaminated soil is to scratch the upper layer and replace with fresh soil. If residents cannot afford complete scratch, the addition of fresh earth on contaminated soil can protect residents from contamination.
Even without correction, there are many ways that residents can reduce their exposure. The most direct is to limit contact with the ground. For children, it could mean going to clean the parks to play in dirt. For adults, this could always mean wearing gloves during gardening.
To avoid continuous exposure inside, residents can regularly wash their hands, remove their shoes when you enter the house, wipe the pets after playing in the courtyard and invest in air purifiers to remove any contaminated dust.
