QUESTION: Is rainwater, collected via lead gutters/flashing etc, used on food crops, a concern? 06/03/12 West Sussex, UK - United Kingdom
Dear LEAD Group
rainwater harvesting over lead gutters and other lead roofing materials into butts used for irrigating food plants is common in my village. Is there any reason for concern over this widespread practise, and is there data you can share as to the range of levels of lead found in water collected in this manner?
ANSWER: Mar 6 2012
the best test that you could request, to answer your question, is a blood lead test, and I would recommend this test for anyone who has ingested food plants grown in soil watered by rainwater harvested from lead gutters, lead flashing etc. In fact, even if rainwater is harvested from non-lead gutters or roof collection areas with no lead flashing, there is a possibility of lead from other sources being in the water. Once lead-contaminated water is applied to agricultural soil, especially if it is applied to soil over a long period of time, there is a good chance that lead contamination has accumulated in the soil. Crops grown, and specifically the edible parts of crops grown in that lead-contaminated soil, will take up lead at differing rates, dependent on the species, the pH of the soil, the amount of organic material in the soil, etc, but you should also consider that the edible parts of plants will often have soil ON them as well (not just lead from the soil IN them). Thus a person who eats unwashed leafy greens or herbs, root vegetables, low-growing fruits like strawberries, etc, will be more at-risk of lead exposure than a person who eats home-grown food prepared by someone who is meticulous about washing food crops or peeling the skin.
I recommend that all family members have a blood lead test but people vary in their rate of absorption of lead from food (and from soil or water if these are ingested directly) so if you only request a blood lead test for one member of a family who is eating home-grown food watered with potentially lead-contaminated water, then it should be the most at-risk member, that is young children. Children are much more likely to eat soil directly (through hand-to-mouth activity, which is normal up to the age of 18 months) and children absorb some 50% of any lead that gets into the gut, compared to adults who only absorb 10-15% of the lead that gets into their gut. However, at any age it seems, lead is much more likely to be absorbed from the gut if the lead is ingested after a long period of not eating eg at breakfast time. The empty stomach of an adult can absorb up to 64% of the lead, due to increased acid levels in the stomach. Thus, people who go for many hours between meals, absorb more lead from their food than people who eat 5-7 small meals a day.
Children are more susceptible to the effects of lead because their brains are still developing, but it is also vital to know the blood lead level of any adult with hypertension, hearing, memory or balance problems, infertility, miscarriage, impotence or slowed reaction time, as these can all be caused by lead.
If you find that anyone who has been eating the rainwater-irrigated food plants has a blood lead level above 2 micrograms per decilitre, then I would recommend that you ask your local health authority to test the irrigated soil for lead, and to also test the rainwater directly from the butts. However, it is worthwhile noting that lead in the blood may also be coming from other more usual sources such as dust and soil contaminated by lead from paint, petrol or industrial activities in the area (including historically). The contribution of lead to blood from various sources is best assessed by the local health authority who should also be able to pay for (the usually very expensive) lead analysis of the locally-grown foods to determine which species of food crops pose the greatest lead-risk.
Having all the blood lead levels of people who eat these rainwater-irrigated soil food crops will allow for a proper public health investigation and recommendations as to how to reduce lead exposure in your community. Replacement of lead-contaminated soil, lead gutters, lead flashing and lead-painted roofs with new non lead-contaminated soil, non-l ead gutters, flashing and paint may only be a part of the solution. I am not aware of any such investigation that has been published so such an investigation and appropriately researched recommendations is well overdue.
If you are unable to inspire enough people who are potentially ingesting lead from this rainwater, to have a blood lead test (eg through a letter to the editor of your local newspaper or through phoning in on talk-back radio or just talking to all your neighbours), THEN would be the time to consider just testing your soil or the rainwater for lead. You should be able to find a lab which is accredited for these particular tests, via the United Kingdom Accreditation Service (UKAS) Website: www.ukas.com or phone 02089178400.
These are cheap tests (lead analysis of soil and water) but the results don't actually tell you if people are absorbing lead from their home-grown food. Elevated blood lead results are the only thing that usually inspire health authorities to action and blood lead tests are also among the cheapest of lead tests available. Any doctor can organise blood lead testing.
The most recent blood lead study in the UK that I am aware of is:
Effects of early childhood lead exposure on academic performance and behaviour of school age children Abstract. Chandramouli K, Steer CD, Ellis M, Emond AM. Archives of Disease in Childhood 2009 Nov; 94(11):844-848 Published Online First: 21 September 2009. Please find it attached with filename: <Chandramouli Early childhood lead exposure, academic performance & behaviour 200909.pdf>. It mentions lead pipes but not lead gutters.
The most recent activity regarding blood lead testing in the United Kingdom and Republic of Ireland that I am aware of is dated 1 July 2010, and titled "Health Protection Agency to investigate lead poisoning among children". Latest news - November 2012, Interim results of the project have now been published in the 2011-2012 BPSU annual report, available at: BPSU Annual Report 2011-2012
Tragically, the investigation was only to occur if the children are showing symptoms of lead poisoning AND are blood lead tested by a consultant paediatrician. This limitation in the planned investigation of 2010 is tragic because there are permanent negative health and development consequences occurring even when blood lead levels are not high enough to cause symptoms (or to induce symptoms that inspire parents to take their children to a paediatrician and ask for a blood lead test) and public health investigations of lead poisoning should NEVER be age-limited because even though children are at increased risk of ingesting lead, and they absorb more of the lead they ingest, and they are more sensitive to the lead that is absorbed, nevertheless adults CAN be exposed to lead and can reach very high (and damaging) blood lead levels without showing any symptoms at the time of the exposure.
This is why I began and will finish this email by recommending that you ask your doctor for blood lead testing.
I'd be very keen to hear back from you when you have any results.
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