Effects of exposure to fine atmospheric particulate matter and its main components during pregnancy on cognitive and motor performance in 1-year-old children

Fine particulate matter (PM_2.
5) pollution is a major public health problem
worldwide, especially in developing countries.
In recent years, the neurological effects of PM_2.
5 exposure have received increasing attention, and susceptible populations, such as pregnant women and children, may be more sensitive
to its toxicity.
Pregnancy PM_2.
5 exposure has been suggested as a potential risk factor
for offspring neurobehavioral development.
PM_2.
5 is a complex mixture of multiple chemical components emitted from different sources, and the toxicity of different chemical components varies
greatly.
However, previous studies on the effects of exposure to different components of PM_2.
5 on children's neurodevelopment have been limited, and most of them have been conducted in low-pollution areas such as North America and Western Europe.
Evidence is lacking
in countries with medium and high pollution levels, including China.

In response to the above problems, the team of Professor Tian Ying and Gao Yu of the School of Public Health of Shanghai Jiao Tong University School of Medicine published an article entitled "Effects of prenatal exposure to PM_2.
5" in the 170th volume of Environment International in October and its composition on cognitive and motor functions in children at 12 months of age: the Shanghai Birth Cohort study
.
The study was based on a birth cohort study that evaluated the effects
of exposure to PM_2.
5 and its main chemical components during pregnancy on cognitive and motor performance in 1-year-olds.

The study was based on the Shanghai Birth Cohort (SBC) and included 2435 mother-infant
pairs.
Pregnancy exposure assessment was performed based on the participants' baseline residential addresses, combined with a high spatiotemporal accuracy PM 2.
5 component concentration dataset inverted by multi-source data fusion, including PM_2.
5 and its primary particulate matter (black carbon BC and mineral dust DUST) and secondary particulate matter (organic matter OM, ammonium _NH4⁺, nitrate_NO3^- and sulfate_SO4^2-) components
.
The Age and Development Process Questionnaire (ASQ^® -3) Assess the baby's cognitive (3 energy zones: communication, problem solving, and individual-social) and motor (2 energy zones: gross motor and fine motor) skills
at 12 months of age.
A linear regression model was used to evaluate the association
between the exposure levels of PM_2.
5 and its components during pregnancy and the scores of children's cognitive and motor energy in the five energy regions.

The study analyzed the association between early (T1), middle (T2), late (T3), and entire pregnancy PM_2.
5 exposure and children's cognitive and motor performance (Figure 1).

The multifactorial adjusted results showed that_PM2.
5 exposure in the third trimester and the whole pregnancy showed a significant negative association
with gross motor movements, problem solving, and personal-social energy zone scores.
In the third trimester, for every 10 μg^{/m increase} in PM_2.
5 exposure concentration, the scores of gross movement, problem solving, and individual-social energy zones decreased by 11.
77 (95% CI: −19.
73, −3.
82), 10.
36 (95% CI: −15.
86, −4.
86), and 12.
34 (95% CI: −18.
73, −5.
95), respectively.
For every 10 μg^{/m increase} in PM_2.
5 exposure throughout pregnancy, gross motor movement, problem solving, and individual-social energy zone scores were reduced by 15.
60 (95% CI: −30.
36, −0.
83), 11.
74 (95% CI: −21.
95, −1.
53), and 18.
87 (95% CI: −30.
72, −7.
01),
respectively.
However, no significant association
between_PM2.
5 exposure in the first or second trimester of pregnancy and cognitive and motor performance in children was observed.

Figure 1: Association of PM_2.
5 exposure during pregnancy with cognitive and motor performance in children

Source: Environment International

The association between exposure in the third trimester and throughout pregnancy and children's cognitive and motor performance was further evaluated for the main chemical components of PM_2.
5 (Figure 2).

The results showed that the exposure of PM_2.
5 components was significantly negatively correlated with the scores of the five energy regions, and the exposure of each component was associated with the reduction of the scores of at least two energy regions.
In particular, exposure to almost all components (except OM) was associated with
lower scores in the problem-solving region.
For example, for every 10 μg/m3 increase in BC, DUST,_{NH 4}+_{, NO3}-, SO4 ^2- exposure in the third trimester, the score of the child's problem-solving zone decreased by 4.
68 (95% CI: −7.
84^{, −}1.
53)~ 10.
79（95%CI：?17.
40, ?4.
18）； For every 10 μg^{/m 3} increase in DUST, NH4+, _SO4^2-exposure throughout pregnancy, the score of the child's problem-solving zone decreased by 10.
31 (95% CI: −19.
41, −1.
21) ~ 11.
69 (95% CI: −21.
36^{, −}2.
02)
。 At the same time, primary and partial secondary component exposure (OM and ^NO3-₎ was also associated with reduced gross action scores; Secondary component exposure was also associated with communication (OM and_NO3-), fine motor (NH4⁺, ^NO3- and_SO42-), and^{individual-social} energy zone scores (_NH4).
⁺) Lower related
.

Figure 2: Association of_PM2.
5 component exposure during pregnancy with cognitive and motor performance in children

Source: Environment International

The study conducted subgroup analyses of children's sex and breastfeeding status to explore potential differences
between groups.
The results showed that the association of exposure to PM_2.
5 and its components with cognitive and motor performance in children was generally stronger
in boys compared to girls.
The association of exposure to PM_2.
5 and its components with cognitive and motor performance is generally stronger in children with breastfeeding < 6 months compared with children who have been breastfeeding for ≥ 6 months; Suggesting breastfeeding may help mitigate adverse effects of exposure to PM_2.
5 and its components on children's cognition and motor performance
.
However, it is important to note that breastfeeding may also represent other healthy behaviours (e.
g.
vegetable/fruit intake) during pregnancy, so more research is needed to validate
this result.

This large prospective birth cohort study showed a negative association between PM_2.
5 exposure during pregnancy and children's cognitive and motor performance; At the same time, new epidemiological evidence of negative correlation between different components and multiple energy regions is provided for the specific chemical components of PM_2.
5
.
The results of this study will help to promote the development of air quality prevention policies for specific particulate matter components, which will have important implications
for more effectively reducing the risk of neurodevelopmental abnormalities caused by PM_2.
5 pollution in early life.

Lei Xiaoning, assistant researcher at the School of Public Health, Shanghai Jiao Tong University School of Medicine, is the first author of the paper, and Professor Tian Ying and Professor Gao Yu are the co-corresponding authors
of the paper.
The research was supported
by the National Natural Science Foundation of China, the Shanghai Municipal Natural Science Foundation, the 2020 Collaborative Innovation Cluster of the Shanghai Municipal Health Commission, the Medical Engineering Intersection Program of Shanghai Jiao Tong University, and the New Young Teachers Program of Shanghai Jiao Tong University.