The Neuroscience of Social Progress: Tackling Lead Poison and Malnutrition

Jul 20, 2024

Gender interventions often target attitudes directly, raising awareness about equality.

But this approach overlooks a crucial precursor: cognitive development. Critical reflection requires reason, logic and empiricism. Curious minds want to learn, read more, discuss alternatives and question tradition. Psychologies also matter in how we handle stress and provocation. When neighbours seem rude, do we lash out or stay calm?

Cognitive capacities are malleable. That’s why we build schools - to support children’s educational development. But new research indicates major obstacles before kids even step into the classroom: lead poison and malnutrition.

Tackling these fundamentals could deliver major dividends - not just for human capital and economic productivity, but also for everyday conversations about culture, inequality, politics and religion.

The aftermath of blasphemy attacks in Pakistan, where blood lead levels are extremely high

Educational Quality has Stagnated in many parts of Sub-Saharan Africa and South Asia

Alexis Le Nestour, Laura Moscoviz, Justin Sandefur present comparable, survey-based literacy tests for cross-sections of men and women born between 1950 and 2000, for 87 countries. Literacy conditional on completing five years of schooling has stagnated, and there have been absolute declines in both South Asia and sub-Saharan Africa.

Why has educational quality stagnated?

There are many possible factors, ranging from teacher absenteeism, over-crowded classrooms, to poor school management. Recent research highlights two additional ways to boost performance: tackling lead poison and malnutrition.

Lead poisoning rots your brain

Lead poisoning rots your brain. Babies exposed to lead are more likely to academically under-perform, get suspended, and become violent criminals.

In Rhode Island, economists Anna Aizer and Janet Currie shows that a one-unit increase in lead increased the probability of suspension from school by almost 10% and the probability of detention by between 27 to 74%.

Leaded gasoline was a major cause of poison in the US, but that varied with geography. Lead bioavailability is highest in areas with non-neutral pH, like the South-East and East. Exploiting this subnational variation, Federico Curci and Federico Masera show areas with more lead saw more violent crime.

New research suggests that even mild lead exposure can cause IQ loss in the majority of children. Scientists have developed a way to estimate IQ loss based on blood lead levels in children under five. This ‘blood lead level-IQ loss function’ comes from analysing seven different studies across multiple countries.

Lead affects Everyone in the Classroom

A fascinating new paper by Ludovica Gazze, Claudia Persico and Sandra Spirovska examines how lead pollution affects not just the exposed children, but also their peers.

The economists used a novel dataset that links blood lead level tests for children in North Carolina to their education records. This allows them to track how lead exposure before age 6 affected children’s academic performance and behaviour throughout their school years.

Children with higher blood levels experience:

Lead-Exposed Children are Disruptive

Gazze et al also examine how lead-exposed classmates impacted other children, who were perfectly healthy.

To isolate the causal effects, the authors compared siblings whose grade cohorts happened to have different proportions of lead-exposed peers, while controlling for family background, school quality, and other factors. This allowed them to pinpoint the impacts of lead-exposed classmates, separate from other influences.

What did they find?

Having more lead-exposed peers in your grade significantly increased the likelihood of being suspended from school and decreased the chances of graduating high school or taking the SAT.

They state,

“Attending school with 10 percent more lead poisoned peers increases the suspension rate by 1.6 percent above the mean of 12.4 percent, and increases the suspension duration by one hour based on a 8-hour school day”

That makes sense. If some children are disruptive, others may emulate to look cool and make friends. Peers encourage disruptive behaviour. Everyone’s education suffers from some kids having lead poisoning.

Disruptive peers affect their same gender

Unsurprisingly, children are more negatively affected by peers of their same gender. Impacts also seemed to be driven primarily by exposure to disruptive students in middle school rather than elementary school.

Peer effects disproportionately harmed Black students and students from disadvantaged backgrounds.

Lead poisoning hurts kids’ education progress. This is now amply demonstrated.

Ludovica Gazze, Claudia Persico and Sandra Spirovska should be congratulated in documenting that lead poison also causes disruption, adversely affects peers. And that’s consistent with a larger body of research on lead poison and violence.

Tangentially, let me flag this fantastic new paper by Laura Kawano and colleagues, on how military families’ quasi-random assignment in ‘better’ neighbourhoods substantially improved their children’s subsequent education and earnings. Neighbourhoods matter!

While the Gazze et al. study focuses on North Carolina, lead pollution remains a global issue with particularly severe implications for developing countries.

Lead Pollution remains High, Globally

In countries with strong environmental mobilisation and strong state capacity, lead poisoning has been massively reduced. Even in Flint (Michigan), children’s blood lead levels reduced from 2.33 micrograms per deciliter in 2006 to 1.15 micrograms per deciliter in 2016. Early interventions can even reverse the effects of prior exposure.

In low and middle income countries (LMICs), regulation is typically far weaker. So when the USA toughened up regulation, lead-acid batteries were then exported to Mexico. Babies born near these recycling plants were more likely to be underweight.

In LMICs, children’s blood lead levels often exceed 5 μg/dL. It is dangerously high in Egypt (8.24), Palestine (9.3) and Pakistan (9.27). It’s over 10 in Telegana, Tamil Nadu and Rajasthan.

Here’s another estimate:

In a study of groundwater quality throughout Pakistan’s Sindh province, “54% of samples contained lead concentrations above 10 µg/L, and 23% of the samples contained more than 50 µg/L. The highest measured concentration was 111 µg”!!!!

Given the well-documented research on lead and violence, I wonder if poison has contributed to ongoing blasphemy mob attacks?

An angry Pakistani demonstrator torches Christian's belongings in Lahore during a protest over a blasphemy row. — Homes set on fire, over religion

Malnutrition

Lead pollution isn’t the only environmental factor affecting cognitive development. Malnutrition also plays a crucial role, as recently highlighted by the Economist.

150 million children are presently malnourished. That’s 22% of under-fives.

This hurts cognitive development. All scientists agree, brains need food. The World Health Organisation is emphatic,

“Stunting holds children back from reaching their physical and cognitive potential”.

Low agricultural productivity is a major part of the problem in Sub-Saharan Africa, resulting in low yields, unstable exports, and high urban food prices.

The Neuroscience of Social Progress

Lead pollution and malnutrition hurt children’s cognitive development, adversely affecting education and catalysing wider disruption.

Tackling these fundamentals would build stronger foundations for sensitive conversations about politics and culture. This approach doesn't negate the importance of cultural interventions but rather enhances their effectiveness by ensuring that individuals have the cognitive capacity to engage in critical reflection and open dialogue.

So, let me suggest that before development agencies rush in with awareness-raising activities, let’s focus on the fundamentals: ending lead poison and malnutrition.