Tag Archives: lead

The main route of lead poisoning is from the soil by way of food, dust, and smoke.

5 Replies

While several towns have had problems with lead in their water, the main route for lead entering the bloodstream seems to be from the soil. The lead content in the water can be controlled by chemical means that I reviewed recently. Lead in the soil can not be controlled. The average concentration of lead in US water is less than 1 ppb, with 15 ppb as the legal limit. According to the US geological survey, of lead in the soil, 2014., the average concentration of lead in US soil is about 20 ppm. That’s more than 1000 times the legal limit for drinking water, and more than 20,000 times the typical water concentration. Lead is associated with a variety of health problems, including development problems in children, and 20 ppm is certainly a dangerous level. Here are the symtoms of lead poisoning.

Several areas have deadly concentrations of lead and other heavy metals. Central Colorado, Kansas, Washington, and Nevada is particularly indicated. These areas are associated with mining towns with names like Leadville, Telluride, Silverton, Radium, or Galena. If you live in an areas of high lead, you should probably not grow a vegetable garden, nor by produce at the local farmer’s market. Even outside of these towns, it’s a good idea to wash your vegetables to avoid eating the dirt attached. There are hardly any areas of the US where the dust contains less than 1000 times the lead level allowed for water.

Lead content of US soils, from the US geological survey of soils, 2014. Michigan doesn’t look half bad.

Breathing the dust near high-lead towns is a problem too. The soil near Telluride Colorado contains 1010 mg/kg lead, or 0.1%. On a dust-blown day in the area, you could breath several grams of the dust, each containing 1 mg of lead. That’s far more lead than you’d get from 1000 kg of water (1000 liters). Tests of blood lead levels, show they rise significantly in the summer, and drop in the winter. The likely cause is dust: There is more dust in the summer.

Recalled brand of curry powder associated with recent poisoning.

Produce is another route for lead entering the bloodstream. Michigan produce is relatively safe, as the soil contains only about 15 ppm, and levels in produce are generally far smaller than in the soil. Ohio soils contains about three times as much lead, and I’d expect the produce to similarly contain 3 times more lead. That should still be safe if you wash your food before eating. When buying from high-lead states, like Colorado and Washington, you might want to avoid produce that concentrates heavy metals. According Michigan State University’s outreach program, those are leafy and root vegetables including mustard, carrots, radishes, potatoes, lettuce, spices, and collard. Fruits do not concentrate metals, and you should be able to buy them anywhere. (I’d still avoid Leadville, Telluride, Radium, etc.). Spices tend to be particularly bad routes for heavy metal poisoning. Spices imported from India and Soviet Georgia have been observed to have as much as 1-2% lead and heavy metal content; saffron, curry and fenugreek among the worst. A recent outbreak of lead poisoning in Oakland county, MI in 2018 was associated with the brand of curry powder shown at left. It was imported from India.

Marijuana tends to be grown in metal polluted soil because it tolerates soil that is too polluted fro most other produce. The marijuana plant concentrates the lead into the leaves and buds, and smoking sends it to the lungs. While tobacco smoking is bad, tobacco leaves are washed and the tobacco products are regulated and tested for lead and other heavy metals. If you choose to smoke cigarettes, I’d suggest you chose brands that are low in lead. Here is an article comparing the lead levels of various brands. . Better yet, I’s suggest that you vape. There are several advantages of vaping relative to smoking the leaf directly. One of them is that the lead is removed in the process of making concentrate.

Some states test the lead content of marijuana; Michigans and Colorado do not, and even in products that are tested, there have been scandals that the labs under-report metal levels to help keep tainted products on the shelves. There is also a sense that the high cost encourages importers to add lead dust deliberately to increase the apparent density. I would encourage the customer to buy vape or tested products, only.

Here is a little song, “pollution” from Tom Lehrer, to lighten the mood.

Robert Buxbaum, November 24, 2019. I ran for water commissioner in 2016 and lost. I may run again in 2020. Who knows, this time I may win.

The chemistry of lead in drinking water

2 Replies

Our county, like many in the US and Canada, is served by thousands of miles of lead pipes. Some of these are the property of the government, others sit beneath our homes and are the property of the home-owner. These pipes are usually safe, but sometimes poison us. There is also problem of lead-tin solder. It was used universally to connect iron and copper pipes until it was outlawed in 1986. After years of sitting quietly, this lead caused a poisoning crisis in DC in 2004, and in Flint in 2015-16. Last month my town, Oak Park, registered dangerous lead levels in the drinking water. In an attempt to help, please find the following summary of the relevant lead chemistry. Maybe people in my town, or in other towns, will find some clue here to what’s going on, and what they can do to fix it.

lead pipes showing the three oxides: brown, yellow, and red, PbO2, PbO, and Pb2O3.

Left to itself, lead and solder pipe could be safe; lead is not soluble in clean water. But, if the water becomes corrosive, as happens every now and again, the lead becomes oxidized to one of several compounds that are soluble. These oxides are the main route of poisoning; they can present serious health issues including slow development, joint and muscle pain, memory issues, vomiting, and death. The legal limit for lead content in US drinking water is 15 ppb, a level that is far below that associated with any of the above. The solubility of PbO, lead II oxide, is more than 1000 times this limit 0.017 g/L, or 17,000 ppb. At this concentration serious health issues will show up.

PbO is the yellow lead oxide shown in the center of the figure above, right; the other pipes show other oxides, that are less-soluble, and thus less dangerous. Yellow lead oxide and red lead oxides on the right were used as paint colors until well into the 20th century. Red lead oxide is fairly neutral, but yellow PbO is a base; its solubility is strongly dependent on the PH of the water. In neutral water, its solution can be described by the following reaction.

PbO + H2O(l) –> Pb2+(aq) + 2 OH–(aq).

In high pH water (basic water), there are many OH–(aq) ions, and the solubility is lower. In low pH, acidic water the solubility is even higher. For every 1 point of lower pH the lowubility increases by a factor of 10, for every 1 point of higher pH, it decreases by a factor of ten. In most of our county, the water is slightly basic, about pH 8. It also helps that our water contains carbonate. Yellow lead forms basic lead carbonate, 2PbCO3·Pb(OH)2, the white lead that was used in paint and cosmetics. Its solubliity is lower than that of PbO, 110 ppb, in pure water, or within legal limit in water of pH 8. If you eat white lead, though, it reacts with stomach acid, pH 2, and becomes quite soluble and deadly. Remember, each number here is a factor of ten.

A main reason lead levels a very low today are essentially zero, even in homes with lead solder or pipe, involves involves the interaction with hypochlorite. Most water systems add hypochlorite to kill bacteria (germs) in the water. A side benefit is significant removal of lead ion, Pb2+(aq).

Pb2+(aq) + 2 ClO–(aq) –> Pb(ClO)2(s). 

Any dissolved lead reacts with some hypochlorite ion reacts to form insoluble lead hypochlorite. Lead hypochlorite can slowly convert to Lead IV oxide — the brown pyrophilic form of lead shown on the left pipe in the figure above. This oxide is insoluble. Alkaline waters favor this reaction, decreasing solubility, but unlike with PbO, highly alkaline waters provide no significant advantage.

PbClO+(aq) + H2O(l) –> PbO2(s) + 2 H+(aq) + Cl–(aq)

Lead IV oxide, PbO2 was used in old-fashioned matches; it reacts violently with phosphorus or sulfur. People were sometimes poisoned by sucking on these matches. In the stomach, or the presence of acidic drinking water, PbO2 is decomposed forming soluble PbO:

PbO2(s) +2 H+(aq) + 2 e– –> PbO(s) + H2O(l).

You may wonder at the presence of the two electrons in the reaction above. A common source in water systems is the oxidation of sulphite:

SO3-2(aq)–> SO4-2(aq) + 2 e–.

The presence of sulphite in the water means that hypochlorite is removed.

ClO–(aq) + 2 H+(aq) + 2 e– —> Cl–(aq) + H2O(l).

Removal of hypochlorite can present a serious danger, in part because the PbO2(s) slowly reverts to PbO and becomes soluble, but mostly because bacteria start multiplying. In the Flint crisis of 2016, and in a previous crisis in Washington DC, the main problem, in my opinion was a lack of hypochlorite addition. The lead crisis was preceded by an uptick in legionnaires disease; It killed 12 people in Flint in 2014 and 2015, and 87 were sickened, all before the lead crisis. Eventually, it was the rise of legionaries disease that alerted water officials in Virginia that there was something seriously wrong in Flint. Most folks were unaware because Flint water inspectors seem to have been fudging the lead numbers to make things look better.

Most US systems add phosphate to remove lead from the water. Flint water folks could have stopped the lead crisis, but not the legionnaires, by adding more phosphate. Lead phosphate solubility is 14 ppb at 20°C, and my suspicion is that this is the reason that the legal limit in the US is 15 ppb. Regulators chose 15 ppb, I suspect, not for health reasons, but because the target could be met easily through the addition of phosphate. Some water systems in the US and Canada disinfect with chloramine, not hypochlorite, and these systems rely entirely on phosphate to keep lead levels down. Excess phosphate is used in Canada to lower lead levels below 10 ppb. It works better on systems with hypochlorite.

Chloramine is formed by reacting hypochlorite with ammonia. It may be safer than hypochlorite in terms of chlorite reaction products, a real problem when the water source is polluted. But chloramine is not safe. It sickened 72 soldiers, 36 male and 36 female in 1998. They’d used ammonia and bleach for a “cleaning party” on successive days. Here’s a report and first aid instructions for the poisoning. That switching to chloramine can expose people to lead is called “the chloramine catch”.

Unlike PbO, PbO2 is a weak acid. PbO2 and PbO can react to form red lead, PbO•PbO2(s), the red stuff on the pipe at right in the picture above. Red lead can react with rust to form iron plumbable, an insoluble corrosion resister. A simple version is:

PbO•PbO2(s) + Fe2O3(s) —> 2FePbO3(s).

This reaction is the basis of red-lead, anti-rust compounds. Iron plumbable is considered to be completely insoluble in water, but like PbO it is soluble in acid. Bottom line, slightly basic water is good, as are hypochlorite in moderation, and phosphate.

Robert Buxbaum, November 18, 2019. I ran for water commissioner, and might run again. Even without being water commissioner, I’ll be happy to lend my expertise, for free, to any Michigan town or county that is not too far from my home.

Keeping your car batteries alive.

1 Reply

Lithium-battery cost and performance has improved so much that no one uses Ni-Cad or metal hydride batteries any more. These are the choice for tools, phones, and computers, while lead acid batteries are used for car starting and emergency lights. I thought I’d write about the care and trade-offs of these two remaining options.

As things currently stand, you can buy a 12 V, lead-acid car battery with 40 Amp-h capacity for about $95. This suggests a cost of about $200/ kWh. The price rises to $400/kWh if you only discharge half way (good practice). This is cheaper than the per-power cost of lithium batteries, about $500/ kWh or $1000/ kWh if you only discharge half-way (good practice), but people pick lithium because (1) it’s lighter, and (2) it’s generally longer lasting. Lithium generally lasts about 2000 half-discharge cycles vs 500 for lead-acid.

On the basis of cost per cycle, lead acid batteries would have been replaced completely except that they are more tolerant of cold and heat, and they easily output the 400-800 Amps needed to start a car. Lithium batteries have problems at these currents, especially when it’s hot or cold. Lithium batteries deteriorate fast in the heat too (over 40°C, 105°F), and you can not charge a lithium car battery at more than 3-4 Amps at temperatures below about 0°C, 32°F. At higher currents, a coat of lithium metal forms on the anode. This lithium can react with water: 2Li + H2O –> Li2O + H2, or it can form dendrites that puncture the cell separators leading to fire and explosion. If you charge a lead acid battery too fast some hydrogen can form, but that’s much less of a problem. If you are worried about hydrogen, we sell hydrogen getters and catalysts that remove it. Here’s a description of the mechanisms.

The best thing you can do to keep a lead-acid battery alive is to keep it near-fully charged. This can be done by taking long drives, by idling the car (warming it up), or by use of an external trickle charger. I recommend a trickle charger in the winter because it’s non-polluting. A lead-acid battery that’s kept at near full charge will give you enough charge for 3000 to 5000 starts. If you let the battery completely discharge, you get only 50 or so deep cycles or 1000 starts. But beware: full discharge can creep up on you. A new car battery will hold 40 Ampere-hours of current, or 65,000 Ampere-seconds if you half discharge. Starting the car will take 5 seconds of 600 Amps, using 3000 Amp-s or about 5% of the battery’s juice. The battery will recharge as you drive, but not that fast. You’ll have to drive for at least 500 seconds (8 minutes) to recharge from the energy used in starting. But in the winter it is common that your drive will be shorter, and that a lot of your alternator power will be sent to the defrosters, lights, and seat heaters. As a result, your lead-acid battery will not totally charge, even on a 10 minute drive. With every week of short trips, the battery will drain a little, and sooner or later, you’ll find your battery is dead. Beware and recharge, ideally before 50% discharge

A little chemistry will help explain why full discharging is bad for battery life (for a different version see Wikipedia). For the first half discharge of a lead-acid battery, the reaction Is:

Pb + 2PbO2 + 2H2SO4  –> PbSO4 + Pb2O2SO4 + 2H2O.

This reaction involves 2 electrons and has a -∆G° of >394 kJ, suggesting a reversible voltage more than 2.04 V per cell with voltage decreasing as H2SO4 is used up. Any discharge forms PbSO4 on the positive plate (the lead anode) and converts lead oxide on the cathode (the negative plate) to Pb2O2SO4. Discharging to more than 50% involves this reaction converting the Pb2O2SO4 on the cathode to PbSO4.

Pb + Pb2O2SO4 + 2H2SO4  –> 2PbSO4 + 2H2O.

This also involves two electrons, but -∆G < 394 kJ, and voltage is less than 2.04 V. Not only is the voltage less, the maximum current is less. As it happens Pb2O2SO4 is amorphous, adherent, and conductive, while PbSO4 is crystalline, not that adherent, and not-so conductive. Operating at more than 50% results in less voltage, increased internal resistance, decreased H2SO4 concentrations, and lead sulfate flaking off the electrode. Even letting a battery sit at low voltage contributes to PbSO4 flaking off. If the weather is cold enough, the low concentration H2SO4 freezes and the battery case cracks. My advice: Get out your battery charger and top up your battery. Don’t worry about overcharging; your battery charger will sense when the charge is complete. A lead-acid battery operated at near full charge, between 67 and 100% will provide 1500 cycles, about as many as lithium. 

Trickle charging my wife's car. Good for battery life. At 6 Amps, expect this to take 3-6 hours.

Trickle charging my wife’s car: good for battery life. At 6 Amps, expect a full charge to take 6 hours or more. You might want to recharge the battery in your emergency lights too. 

Lithium batteries are the choice for tools and electric vehicles, but the chemistry is different. For longest life with lithium batteries, they should not be charged fully. If you change fully they deteriorate and self-discharge, especially when warm (100°F, 40°C). If you operate at 20°C between 75% and 25% charge, a lithium-ion battery will last 2000 cycles; at 100% to 0%, expect only 200 cycles or so.

Tesla cars use lithium batteries of a special type, lithium cobalt. Such batteries have been known to explode, but and Tesla adds sophisticated electronics and cooling systems to prevent this. The Chevy Volt and Bolt use lithium batteries too, but they are less energy-dense. In either case, assuming $1000/kWh and a 2000 cycle life, the battery cost of an EV is about 50¢/kWh-cycle. Add to this the cost of electricity, 15¢/kWh including the over-potential needed to charge, and I find a total cost of operation of 65¢/kWh. EVs get about 3 miles per kWh, suggesting an energy cost of about 22¢/mile. By comparison, a 23 mpg car that uses gasoline at $2.80 / gal, the energy cost is 12¢/mile, about half that of the EVs. For now, I stick to gasoline for normal driving, and for long trips, suggest buses, trains, and flying.

Robert Buxbaum, January 4, 2018.

How to help Flint and avoid lead here.

Leave a reply

As most folks know, Flint has a lead-poisoning problem that seems to have begun in April, 2014 when the city switched its water supply from Detroit-supplied, Lake Huron water to their own source, water from the Flint River. Here are some thoughts on how to help the affected population, and how to avoid a repeat in Oakland county, where I’m running for water commissioner. First observation, it is not enough to make sure that the source water does not contain lead. The people who decided on the switch had found that the Flint river water had no significant content of lead or other obvious toxins. A key problem, it seems: the river water did not contain anticorrosion phosphates, and none, it seems, were added by the Flint water folks. It also seems that insufficient levels of chlorine (hypochlorite) were added. After the switch, citizens started seeing disgusting, brown water come from their taps, and citizens with lead pipes or solder were poisoned with ppb-levels of lead. There was also an outbreak of legionaries disease that killed 12 people. It was the legionaries that alerted the CDC to the possibility of lead, since it seems the water folks were fudging the numbers there, and hiding that part of the problem.

Flint water, Sept 2015, before switching back to Lake Huron.

Flint water after 5 hours of flushing, Sept 2015, before switching back to Lake Huron.

The city began solving its problem by switching back to Detroit-supplied, Lake Huron water in October, 2015. Beginning in December, 2015, they started adding triple doses of phosphate to the wate. As a result, Flint tap-water is now back within EPA standards, but it’s still fairly unsafe, see here for more details.

There has been a fair amount of finger-pointing. At Detroit for raising the price of water so Flint had to switch, at water officials ignoring the early signs of lead and fudging their reports, at other employees for not adding phosphate or enough chlorine, and at “the system” for not providing Flint’s government with better oversight. My take is that a lot of the problem came from the ignorance of the water commission, and it’s commissioner. We elect our water commissioners to be competent overseers of complex infrastructure, but in may counties folks seem to pick them the same way they pick aldermen: for a nice smile, a great handshake, and an ability to remember names. That, anyway, seems to be the way that Oakland got its current water commissioner. When you pick your commissioner that way, it’s no surprise that he (or she) isn’t particularly up on corrosion chemistry, something that few people understand, and fewer care about until it bites them.

Flint river water contains corrosive chloride that probably helped dissolve the lead from pipes and solder. Contributing to the corrosion problem, I’m going to guess that Flint River water also contains, relatively little carbonate, but significant amounts of chelating chemicals, like EDTA, in 10s of ppb concentration. EDTA isn’t poisonous at these concentrations, but it’s common in industry and is the most commonly used antidote for lead poisoning. EDTA extracts lead and other metals from people and would tend to contribute to the process of extracting lead and iron oxide from the pipes surface into the drinking water. With EDTA in the water, a lot of phosphate or hypochlorite would be needed to avoid the lead poisoning problem and the deadly multiplication of disease.

Detroit ex-mayor Kwame Kilpatrick has claimed that both Flint water and Detroit water were known to be poisoned even a decade before the switch. I find these claims believable given the high levels of lead in kids blood even before the switch. Also, I note that there are areas of Detroit where the blood-lead levels are higher than Flint. Flint tested at the taps in a way that fudged the data during the first days of the poisoning, and I suspect many of our MI cities do this today — just to make the numbers look better. My first suggestion therefore is to test correctly, both at the pipes and at the taps; lead pipes are most-often found in the last few feet before the tap. In particular, we should test at all schools and other places where the state has direct authorization to fix the problem. A MI senate bill has been proposed to this effect, but I’m not sure where it stands in the MI house. It seems there are movements to add lots of ‘riders’ and that’s usually a bad sign.

Another thought is that citizens should be encouraged to test their private taps and helped to fix them. The state can’t come in and test or rip out your private pipes, even if they suspect lead, but the private owner has that authorization. The state could condemn a private property where they believe the water is bad, but I doubt they could evict the residents. It’s a democratic republic, as I understand; you have the right to be deadly stupid. But I’ll take my own suggestion to encourage you: If you think your water has lead, take a sample and call (517) 335-8184. Do it.

Another suggestion, perhaps the easiest and most important, is drink bottled water for now, and if you feel you’ve been poisoned, take an antidote.  As I understand things, the state is already providing bottles of imported water. The most common antidote is, as I’d mentioned, EDTA. Assuming that Flint River water had enough EDTA to significantly worsen the problem, the cheapest antidote might be Flint River water, assuming you drew it in lead-free pipes and chlorinated sufficiently to rid it of bugs. If there is EDTA it will help the poisoned. Another antidote is Succinic acid, something sold by REB Research, my company. As with EDTA it is non-toxic, even in fairly large doses, but its use would have to be doctor- approved.

Robert E. Buxbaum, January 19-31, 2016. I hope this helps. We’d have to check Flint River water for levels of EDTA, but I suspect we’d find biologically significant concentrations. If you think Oakland should have an engineer in charge of the water, elect Buxbaum for water commissioner.